Observation of asymmetric induction in the cisltrans cyclopropane mixture formed between the reaction of styrene with N2CHCO2R (R = ethyl, Ph) demonstrated participation of the chiral copper complex the product-determining step. See Nozaki, H.; Moriuti, S.; Takaya, H.; Noyori, R. Tetrahedron Lett. 1966,5239. In addition, several patents disclose various copper compounds useful as cyclopropanation catalysts: U. S. Pat. No. 4, 198, 527, Japanese Patent No. 50,116, 465, and European Patent No. 22,608.

The successful, catalytic cyclopropanation of alkenes with diazo reagents requires the use of a transition metal complex to facilitate loss of N2 from the diazo reagent as well as to stabilize the intermediate carbene species against competing carbene dimerization via weak binding to the metal complex. See Doyle, M. P.; Griffin, J. H.; Bagheri, V.; Dorow, R. L. Organometallics 1984,3, 53; Doyle, M. P. Ace. Chem. Res. 1986, 19,348 ; Brookhart, M.; Studabaker, W. B. Chem. Rev. 1987,87, 411; Maxwell, J. L.; Brown, K. C.; Bartley, D. W.; Kodadek, T. Science 1992,256, 1544; and Bartley, D. W.; Kodadek, T. J.

Am. Chem. Soc. 1993,115, 1656. With appropriate choice of metal and supporting ligands, carbene transfer to alkenes can proceed with high levels of stereoselectivity. See Kirmse, W. Angew. Chem., Int. Ed. 2003,42, 1088; Doyle, M. P.; McKervey, M. A.; Ye, T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds ; John Wiley & Sons, Inc.: New York, 1998; Lebel, H.; Marcoux, J. -F. ; Molinaro, C.; Charette, A. B.

Chem. Rev. 2003,103, 977; and Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998, 98, 911.

While complexes of many transition metals may be used in catalytic cyclopropanation, copper is attractive due to its low cost relative to other active metals such as rhodium and ruthenium.

More recently, a variety of Cu (I) complexes supported by multidentate N-donor ligands have been reported that catalyze the cyclopropanation of olefins with diazo esters such as ethyl diazoacetate. See Doyle, M. P. ; McKervey, M. A.; Ye, T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds; John Wiley & Sons, Inc.: New York, 1998 and Lebel, H.; Marcoux, J. -F. ; Molinaro, C.; Charette, A. B. Chem. Rev. 2003, 103,977. While diastereoselectivities are generally modest and may be improved by increasing the size of the diazo reagent and/or supporting ligands, impressive enantioselectivites have been obtained with chiral supporting ligands such as bis (oxazolines) or semicorrins (Figure 15). See Doyle, M. P. ; Bagheri, V.; Wandless, T. J.; Harn, N. K. ; Brinker, D. A.; Eagle, C. T.; Loh, K.-L. J. Am. Chem. Soc. 1990,112, 1906; Diaz-Requejo, M. M.; C aballero, A.; Belderrain, T. R.; Nicasio, M. C.; Trofimenko, S.; Perez, P. J. J. Am. Chem. Soc. 2002,124, 978 ; Pfaltz, A. Acc. Chem. Res. 1993,1993, 339; Doyle, M. P.; McKervey, M. A.; Ye, T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds; John Wiley & Sons, Inc.: New York, 1998 ; Lebel, H.; Marcoux, J. -F.; Molinaro, C.; Charette, A. B. Chem. Rev. 2003,103, 977; and Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998,98, 911. In addition, Pérez and co-workers have shown that electron-deficient tris (pyrazolyl) borates can shift the chemoselectivity of reactions employing N2CHC02Et to give products that derive from carbene insertion into C-H bonds.

See Caballero, A.; Diaz-Requejo, M. M.; Belderrain, T. R.; Nicasio, M. C.; Trofimenko, S.; Perez, P. J. Organometallics 2003,22, 4145; Caballero, A.; Diaz-Requejo, M. M. ; Belderrain, T. R.; Nicasio, M. C.; Trofimenko, S.; Pérez, P. J. J. Am. Chem. Soc. 2003, 125,1446 ; Morilla, M. E.; Molina, M. J.; Diaz-Requejo, M. M. ; Belderrain, T. R. ; Nicasio, M. C.; Trofimenko, S.; Perez, P. J. Organometallics 2003,22, 2914; Morilla, M. E.; Diaz- Requejo, M. M.; Belderrain, T. R.; Nicasio, M. C.; Trofimenko, S.; Perez, P. J.

Organometallics 2004,23, 293; and Diaz-Requejo, M. M.; Belderrain, T. R.; Nicasio, M.

C.; Trofimenko, S.; Perez, P. J. J. Am. Chem. Soc. 2002,124, 896.

Time resolved FT-IR spectroscopy has also been used to identify a transient copper carbene upon addition of N2CHC02Me to a cationic Cu (l) bis (oxazoline) pre-catalyst. See Ikeno, T.; Iwakura, I. ; Yamada, T. J. Am. Chem. Soc. 2002,124, 15152. Despite the potential to develop more selective and versatile catalysts based on a detailed understanding of active species involved, experimental progress has lagged considerably behind theoretical studies aimed at characterizing discrete species involved in copper-catalyzed cyclopropanation. Employing electron-rich B-diketiminato supporting ligands, we report herein detailed structural, spectroscopic, and kinetic studies that outline the nature of copper carbenes formed i n t he catalytic c yclopropanation o f s tyrene w ith N 2CPh2 u sing a C u (I) catalyst. See Bourget-Merle, L.; Lappert, M. F.; Severn, J. R. Chem. Rev. 2002,102, 3031 ;

Dai, X.; Warren, T. H. Chem. Commun. 2001, 1998 ; Spencer, D. J. E.; Aboelella, N. W.; Reynolds, A. M.; Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 2002,124, 2108; Aboelella, N. W.; Lewis, E. A.; Reynolds, A. M.; Brennessel, W. W.; Cramer, C. J.; Tolman, W. B. J. Am. Chem. Soc. 2002,124, 10660; Spencer, D. J. E.; Reynolds, A. M.; Holland, P. L.; Jazdzewski, B. A.; Duboc-Toia, C.; Le Pape, L.; Yokota, S.; Tachi, Y.; Itoh, S.; Tolman, W. B. Inorg. Chem. 2002,41, 6307; Laitar, D. S.; Mathison, C. J. N.; Davis, W. M.; Sadighi, J. P. Inorg. Chem. 2003,42, 7354; Yokota, S.; Tachi, Y.; Nishiwaki, N. ; Ariga, M.; Itoh, S. Inorg. Chem. 2001,40, 5316.

One impact of the investigations of diazo compounds is that several studies have implicated electrophilic carbene intermediates [Cu] =CHR as the active species in cyclopropanation reactions. In fact, Hofmann recently described the low temperature NMR characterization of the Cu-carbene [But2P (NSiMe3) 2-K2NlCu=C (Ph) C (O) Me (1) in a mixture of 2-phenyl-diazoacetate and [But2P (NSiMe3) Z-KZNJCu (ethylene) in toluene-d8.

See Straub, B. F.; Hofmann, P. Angew. Chem. Int. Ed. 2001,40, 1288. Although 1 was found to decompose at room temperature in the absence o f styrene to give 2, 3-diphenyl maleate and fumarate products of carbene coupling, addition of styrene resulted in the disappearance of 1 and gave a mixture of cis and trans-methyl-1, 2-diphenylcyclopropane- carboxylate. This supports the notion that metal carbene intermedaites are the active species in the cyclopropanation reaction.

Other than diazomethane, diazo reagents that do not bear heteroatom-containing (x- substituents are rarely used for catalytic cyclopropanation. This limitation arises from the fact that diazo esters are more stable and thus less prone to catalytic dimerization by metal complexes. See Tomilov, Y. V. ; Dokichev, V. A.; Dzhemilev, U. M. ; Nefedov, 0. M.

Russ. Chem. Rev. 1993,62, 799. It is therefore not surprising that only a few well-defined examples of metal-carbene complexes amenable to catalytic group transfer employing aryldiazomethanes have been reported. In one example, divalent group 8 porphyrin complexes (TTP) Fe (TTP = meso-tetra-p-tolylporphyrinato) and (TPFPP) Os (CO) (TPFPP = meso-tetrakis (pentafluoro-phenyl) -porphyrinato) catalyzed the cyclopropanation of styrene in high yield with N2CH (p-tolyl) and N2CPh2, respectively. See Hamaker, C. G.; Mirafzal, G. A.; Woo, L. K. Organometallics 2001,20, 5171; and Li, Y.; Huang, J. -S. ; Zhou, Z. -Y. ; Che, C. -M. J. Am. Chem. Soc. 2001,123, 4843. The metal carbenes [Fe] =CHAr and [Os] (=CPh) 2 were identified as active intermediates that undergo stoichiometric reactions with styrene to give the corresponding cyclopropane.

Nevertheless, most metal catalysts, especially rhodium acetates and copper complexes, developed for catalytic alkene cyclopropanation with a-carbonyl diazoalkanes N2CRR' (R and/or R'is an acyl or ester group) generally do not work well with aryldiazomethanes (R

and/or R'is a acyl or ester group) because the intermediate metal-carbene complexes are too reactive toward carbene coupling. In order to minimize carbene coupling, the reaction is often conducted in the presence of a large excess of alkene substrate relative to the diazoalkane reagent R'RCNa (100-300: 1 is typical) while also adding the diazoalkane reagent slowly to minimize formation of alkene byproducts. This large excess of alkene substrate can make it difficult to isolate the cyclopropane product from the reaction mixture. Moreover, this process is highly undesirable when only a limited supply of precious alkene is available.

Despite the intense interest in developing catalytic asymmetic synthetic transformations, only a limited number of chiral catalysts for metal carbene transformations have been reported. Chiral catalysts have been reported employing copper (II) complexes of 3-trifluoroacetyl- (+)-camphor and Schiff bases derived from (S)-(-)-l-phenylethylamine, binaphthyl-o, o'-diamines, and tartaric acid. See Aratani, T.; Pure & App. Chem. 1985,57, 1839 ; Aratani, T.; Yoneyoshi, Y.; Nagase, T. Tetrahedron Lett. 1977,30, 2599; and Aratani, T.; Yoneyoshi, Y.; Nagase, T. Tetrahedron Lett. 1982,23, 685. However, these chiral copper catalysts have generally provided only low to moderate enantiomeric excesses in cyclopropanation reactions.

Nakamura and Otsuka reported the preparation of chiral bis (1, 2) - dioximato) cobalt (II) complexes derived from D-camphor. This catalyst has been used for cyclopropanation of conjugated dienes, styrenes, and electron-deficient alkenes that include ethyl acrylate and acrylonitrile. However, vinyl ethers and mono-olefins, including cyclohexene, did not react with diazoesters under the influence of these catalysts, thus suggesting that the intermediate metal carbene possesses nucleophilic character. Optical yields in cyclopropanation reactions catalyzed by this catalyst were reported to be moderate. See Nakamura, A.; Konishi, A.; Tatsuno, Y.; Otsuka, S. J. Am. Chem. Soc.

1978,100, 3443 and 3449.

Summary of the Inventioul The present invention described herein employs Cu (I) and Co (I) complexes of an electron rich, bidentate N, N-donor ligand (p-diketiminate) that reacts with diazomethanes to yield a unique metal-carbene complex that selectively reacts with alkenes to form cyclopropanes without many of the problems mentioned above. In addition, the methodology of the present invention can be readily extended to include the stereoselective cyclopropanation of alkenes.

Our system employs Cu (I) complexes of an electron-rich, bidentate N, N-donor ligand (P-diketiminates) that react with both heteroatom-containing a-substituted diazomethanes and aryldiazomethanes (for example, ethyldiazoacetate and Ph2CN2) to yield a unique metal-carbene complex stabilized by two metal fragments (for example, {[Me2NN] Cu} 2 (U-CPh) 2 and { [Me3NN] Cu} 2 (u-CPh) 2) that selectively reacts with alkenes (for example, styrenes). These examples are the first of isolable Cu-carbene complexes that react with alkenes to give cyclopropanes. This type of stabilized Cu-carbene complex is the active agent responsible for carbene transfer to an alkene under catalytic conditions, in which a solution of diphenyldiazomethane is slowly added over ca. 20 hours to a solution containing an alkene (for example, styrene) and a small amount (ca. 5 mol%) of a copper p-dketiminate complex. No alkenes (<1%) resulting from carbene coupling are observed in the catalytic cyclopropanation of styrene with Ph2CN2 when [Me2NN] Cu (ethylene) is used as a pre-catalyst in toluene solution, although the azine Ph2C=N-N=CPh2 is observed in amounts inversely proportional to the time allowed for diphenyldiazomethane addition.

Furthermore, electron-rich, bidentate N, N-donor ligands can be designed to impart stereo- and enantio-selectivity in the cyclopropanation of alkenes with diazoalkanes.

Brief Description of Figures Figure 1 depicts variable temperature'H NMR spectra (300 MHz) of {[Me2NN]Co}2(µ-O)2 (8) in toluene-d8.

Figure 2 depicts variable-temperature magnetic data for {[Me2NN]Co}2(µ-O)2 in toluene-d8.

Figure 3 depicts a Chem3D model of final coordinates from DFT calculation.

Figure 4 depicts contour density plots of LUMO (left) and LUMO+1 (right) from DFT calculation for linear [Me2NN] Co#NBut illustrating significant Co-N (imide) 71- antibonding interactions.

Figure 5 depicts a fully labeled ORTEP diagram of [Me2NN] Co (l16-toluene) (all H atoms omitted).

Figure 6 depicts a fully labeled ORTEP diagram of {[Me2NN] Co} 2 (li-0) 2 with bridging oxo atoms (O1 and O1') in sites of major (86%) occupancy (all H atoms omitted).

Figure 7 depicts a fully labeled ORTEP diagram of {[Me2NN] Co} 2 (, u-0) 2 with bridging oxo atoms (02 and 03) in sites of minor (14%) occupancy (all H atoms omitted ; 0 atoms refined isotropically as described above). The cobalt and p-diketiminato atom positions remain unchanged.

Figure 8 depicts a fully labeled ORTEP diagram of {[Me2NN]Co}2(µ-NAr) 2 (all H atoms omitted).

Figure 9 depicts a fully labeled ORTEP diagram of [Me2NNlCo-NAd (all H atoms omitted).

Figure 10 depicts a fully labeled ORTEP diagram of {[Me2NN] Co} 2 (p-O) (l-NAr) (all H atoms omitted).

Figure 11 depicts an ORTEP diagram of {[Me2NN]Co}2(µ-CPh2) (all H atoms omitted).

Figure 12 depicts preparation of bimetallic carbene complex.

Figure 13 depicts carbene group transfer reactions.

Figure 14 depicts an X-ray crystal structure of {[Me2NN]Cu}(µ-CPh2).

Figure 15 depicts known supporting ligands used in copper cyclopropanation catalysts.

Figure 16 depicts variable temperature 1H NMR spectra (300 MHz) of the ketiminato backbone region of {[Me2NN]Cu}(µ-CPh2) in toluene-d8- Figure 17 depicts a van't Hoff plot for the dissociation of a [Me2NN] Cu fragment from {[Me2NN]Cu}(µ-CPh2) in toluene-d8.

Figure 18 depicts a representative UV-vis spectrum for the cyclopropanation of styrene (100 equiv. ) by [Me2NN] Cu=CPh2 (dioxane, 30. 2 °C).

Figure 19 depicts an Eyring plot for the cyclopropanation of styrene by [Me2NN] Cu=CPh2 in dioxane over the temperature range 17.5-60. 2 °C.

Figure 20 depicts variable temperature 1H NMR spectra (300 MHz) of {[Me2NN] Cu} 2 (1l-CPh2) in toluene-d8. Full spectrum recorded at-70 °C (a, bottom) and variable-temperature inset showing the p-diketiminato N-aryl and backbone methyl groups (b, top).

Figure 21 depicts plots of ln [(At-AOO)/(A0-A)] vs. time from 17.5-60. 2 °C for the stoichiometric cyclopropanation of styrene (100 equiv. ) by [Me3NN] Cu=CPh2 in 1,4- dioxane.

Figure 22 depicts UV-Vis spectra used to monitor the decomposition of [Me3NN] Cu=CPh2 in dioxane at 32. 2 °C.

Figure 23 depicts a fully labeled ORTEP diagram of {[Me2NN]Cu}2(µ-CPh2) (all H atoms omitted). Selected bond distances (A), angles (deg), and twist angles between

planes: Cul-C43 1.922 (4), Cu2-C43 1.930 (4), Cul-Cu2 2.4635 (7), Cul-NI 1.965 (3), Cul- N2 1.955 (3), Cu2-N3 1.970 (3), Cu2-N4 1.978 (3), Cul-C43-Cu2 79.51 (14), Nl-Cul-N2 96.11 (13), N3-Cu2-N4 95.85 (12), C44-C43-C50 115.0 (3), Nl-Cul-N2/C44-C43-C50 89.1, N3-Cu2-N4/C44-C43-C50 83. 1.

Figure 24 depicts a fully labeled ORTEP diagram of [Me3NN] Cu=CPh2 (all H atoms omitted). Selected bond distances (A), angles (deg), and twist angles between planes (deg) : Cu-C24 1. 834 (3), Cu-Nl 1.906 (3), Cu-N2 1.922 (3), Nl-Co-N2 96.10 (12), C25- C24-C31 117.3 (3), Nl-Cu-N2/C25-C24-C31 89. 0.

Figure 25 depicts a Hammett plot of for cyclopropanation of p-substituted styrenes.

(* denotes estimated value due to overlapping GC peaks in competition experiment).

Detailed Description of the Invention The invention will now be described more fully with reference to the accompanying examples, in which certain preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Overview of a Preferred Eiiiboditnent The present invention relates generally to B-diketiminato transition metal catalysts that are useful for the catalytic cyclopropanation of alkenes. A procedure to form cyclopropane rings is highly valuable because it provides a method to prepare cyclopropane rings which are common features of many natural products and pharmaceuticals. Although much research has been conducted to develop methods for forming cyclopropane rings, procedures that entail addition of a carbene fragment (CRR') derived from a non a- carbonyl diazoalkane N2CRR'to an alkene to form a cyclopropane, where R and R'is not a acyl or ester group, generally do not work well in the presence of known metal catalysts.

Consequently, the present invention solves this problem and is readily adaptable to the diastereoselective and asymmetric synthesis of cyclopropanes.

One aspect of the present invention relates to P-diketiminato transition metal compounds. The transition metal can be copper or cobalt. The diketiminato ligand is coordinated to the transition metal atom through two nitrogen atoms bonded to the backbone of the diketiminato ligand. Furthermore, the diketiminato ligand can be

optionally substituted with halogens, alkyl groups, or aryl groups. In preferred embodiments, the transition metal is copper and the nitrogen atoms of the diketiminato ligand are substituted with 2, 6-dimethylphenyl groups. The transition metal atom of the compound is also coordinated to a carbene. In certain embodiments, the carbene is derived from ethyl diazoacetate (EDA; N2CHC02Et). In preferred embodiments, the carbene is diphenylmethyl carbene. In certain embodiments, the P-diketiminato compound is chiral.

Another a spect o f the present invention relates to a method o preparing c arbene stabilized P-diketiminato transition metal compounds. A preferred procedure involves addition of a diazo compound to two equivalents of a p-diketiminato transition metal compound coordinated to a ligand. In a preferred embodiment, the diazo compound is N2CPh2 or N2CHC02Et. The ligand that is displaced from the transition metal can be an alkene, arene, or amine. In a preferred embodiment, the ligand is an alkene such as ethylene. In c ertain embodiments, the c arbene stabilized p-diketiminato transition m etal compound can be isolated and purified by crystallization form solution.

Another aspect of the present invention relates to a method of preparing cyclopropanes using carbene stabilized p-diketiminato transition metal compounds. In certain embodiments, a mixture of the alkene and carbene stabilized p-diketiminato transition metal compound is allowed to react at room temperature. In certain embodiments, a large excess (ca. 20 fold) of alkene is used relative to the amount of carbene catalyst. The progress of the reaction may be monitored by gas chromatographic analysis. This procedure has been shown to give quantitative yields of cyclopropane products in certain cases. In certain embodiments, the carbene stabilized B-diketiminato transition metal compound may be used in catalytic amounts. A solution containing the alkene and a catalytic amount of the p-diketiminato copper-ligand compound is treated with the diazo compound. In a preferred embodiment, the alkene is styrene and the diazo compound is N2CPh2. In another preferred embodiment, the alkene is styrene and the diazo compound is N2CHC02Et. In some cases, it may be necessary to add the diazo compound slowly (over a time span of ca. 20 hours) to avoid formation of products derived from coupling of the carbene moieties. In certain embodiments, the carbene stabilized p- diketiminato transition metal compound is chiral. In certain embodiments, the cyclopropane product is formed in a diastereomeric excess or enantiomeric excess of greater than 80%. In a preferred embodiment, the cyclopropane product is formed in a diastereomeric excess or enantiomeric excess of greater than 95%.

Preparation of Copper ffiDiketimiflato Stabilized Catalvsts Transition metal p-diketiminato stabilized catalysts can be generally prepared by addition of a diazo compound to two equivalents of a p-diketiminato transition metal compound coordinated to a ligand. In a preferred embodiments, the transition metal is copper or cobalt. The ligand that binds to the transition metal could be an optionally substituted pyridine, organonitriles (e. g acetonitrile, or derivates thereof), or optionally substituted primary, secondary and tertiary alkyl amines, and optionally substituted aryl amines. In addition, the ligand could also be a isonitrile, phoshine, organosulfide, or organoarsine. Representative examples of alkyl amines include methylamine, ethylamine, isopropyl amine, dimethyl amine, diethyl amine, diisopropyl amine, triethyl amine, tripropylamine, tributylamine, and the like. Representative examples of aryl amines include pyridine, lutidine, 2,3-lutidine, 2,4-lutidine, 2,5-lutidine, 2,6-lutidine, 3,4-lutidine, and various pyridines that are substituted with alkyl substituents having 1-6 carbon atoms.

In one specific embodiment, the addition of N2CPh2 to 2 equiv.

[Me2NN] Cu (ethylene) (2) in toluene at-35 °C resulted in immediate effervescence and the formation of a purple solution from which {[Me2NN] Cu} 2 (ll-CPh2) (3) may be isolated in 40% yield as purple crystals from ether (Scheme la). The X-ray structure of 3 e hexane shows the diphenylcarbene unit nearly symmetrically bound between two [Me2NN] Cu fragments separated by 2.458 (3) A with Cul-C43 and Cu2-C43 distances of 1.912 (3) and 1.913 (4) A. These distances may be compared against bridging spa-hybridized aryl groups in multinuclear Cu (I)-aryls for which a range of Cu-C and Cu-Cu distances of 1.96-2. 04 and 2.4-2. 5 A, respectively, has been established. The two [Me2NN] Cu fragments are related by a non-crystallographic C2-axis through C43 that bisects the Cu-Cu vector and each [Me2NN] Cu fragment is essentially orthogonal to the CPh2 moiety (89.2 and 89.9 twist angles between the N-Cu-N and C44-C43-C50 planes).

ScAzeene l a. Synthesis of 3.

The 1H spectrum of 3 in toluene-d8 at-70 °C (300 MHz) is consistent with its structure in the solid state, giving rise to four separate p-diketiminate Ar-Me resonances, two backbone-Me resonances at 8 1.639 and 1.565 ppm and one backbone-CH signal at 5

5.010 ppm. The carbene CPh2 13C {lH} NMR signal is downfield of the other signals at 8 189 ppm. Warming this solution results in the coalescence of the backbone-Me signals at- 25 °C which is consistent with a concerted rotation of each [Me2NN] Cu fragment about its respective Cu-CPh2 vector for which an activation barrier AG = 10 (1) kcal/mol could be established at this temperature. All four Ar-Me resonances also coalesce above 25 °C as a result of an enatiomerization process. While this could involve rapid dissociation/reassociation of one [Me2NN] Cu fragment from 3, more likely is a facile twist about the vector containing C43 that bisects the Cul-Cu2 axis.

Variable temperature NMR spectra also reveal that 3 is in a reversible equilibrium with two new C2v-symmetric-diketiminate species 4 and 5 that possess backbone-CH signals at 8 4.958 and 4.801 ppm with corresponding Ar-Me resonances at 8 2.03 and 2.40 ppm, respectively. The concentrations of 4 and 5 are identical and increase with increasing temperature; at-70 °C they exist in a 1: 1: 50 ratio with respect to 3 while at +60 °C the ratio is 1: 1: 4.5. Since 5 could be identified as [Me2NN] Cu (toluene) by addition of an authentic sample (prepared from CuBr and Tl [Me2NN] in toluene) to the mixture at room temperature, this suggests that 3 dissociates in toluene to give an equilibrium concentration of 5 and the monomeric carbene [Me2NN] Cu=CPh2 (4) (Scheme 2; Figure 16). A related Cu (I)-benzene adduct supported by a fluorinated p-diketiminate ligand has been structurally characterized by Sadighi. See Laitar, D. S.; Mathison, C. J. N. ; Davis, W. M. ; Sadighi, J. P.

Inorg. Chem. 2003,42, 7354. The temperature dependence of the equilibrium constant over the temperature range 0-70 °C allows the determination of AH = 10 (1) kcal/mol and AS = 19 (3) cal/mol¢K for the dissociation of one [Me2NN] Cu fragment from 3. Notably, there is no sign of broadening of the closely spaced backbone-CH resonances of 3 and 4 indicating that their interconversion is not fast on the NMR timescale at 70 °C.

Sclieiiie 2. Reactivity of 3. 3 tluene-d$ MezCu=CPhz + [Me2NN] Cu (toluene) 4 5 3 styrene/N2CPh2 Ph Ph t-? + 2 [Me2NN] Cu (styrene) Ph2C=N-N=CPh2 Ph Ph

Simple molecular orbital considerations as well as preliminary DFT calculations suggest that a monomeric carbene would favor an orientation in which the carbene is orthogonal to the p-diketiminate backbone to maximize Cu-carbene backbonding intereactions with the filled d orbital most destabilized by-interactions of the N-donor atoms (Scheme 3; Table 1). Thus, the unique binuclear stabilization of the CPh2 moiety in 3 in which each [Me2NN] Cu fragment is orthogonal to the CPh2 unit may be a result of optimizing backbonding interactions from two [Me2NN] Cu fragments.

Scheme 3. Copper-carbene backbondinging interactions. N z--Ih y -N, I z (filled dyz to carbene py) Backbonding by one Backbonding by two [Me2NN] Cu fragment [Me2NN] Cu fragments I (R = H) III (R = H) II (R = Ph) IV (R = Ph) Table 1. Calculated bond distances (A) and angles (°) for models I, III-C2v, and III-C2. Parameter I III-C2v III-C2 Cu-C 1. 785 1. 885 1. 892 1. 904 (Cu-Nl) Cu-N 1. 917 1. 932 1 924 (Cu-N2) Cu-Cu n/a 2. 530 2. 321 * N-Cu-N 92. 5 95. 5 95. 3 Cu-C-Cu n/a 84. 5 75. 7 N-Cu-N/H-C-H 90 90 89. 2 * In sterically unencumbered III-C2, the Cu centers can approach each other much closer than possible in 3 (Cu-Cu = 2.4635 (7) A). Constraining the Cu-Cu distance to 2.46 A did not result in calculated energies or metrical parameters markedly different from those of unconstrained III-C2-

Synthesis and Characterization of Terminal Carbene [Me3NN]Cu=CPh2.

Nonetheless, steric factors undoubtedly play a role in the relative stability of mono- and dicopper carbenes. Given the small enthalpy of dissociation from 3 to generate the terminal carbene [Me2NN] Cu=CPh2 (4), we felt that a slight modification to the (3- diketiminate ligand might sufficiently destabilize this singly-bridged dicopper species to isolate a terminal carbene. Low temperature addition of N2CPh2 to an ether solution of [Me3NN] Cu (toluene) that possesses an additional methyl group in the 4-position of each p- diketiminato N-aryl ring results in the isolation of the terminal carbene [Me3NN] Cu=CPh2 (8) as purple crystals in 20% recrystallized yield (Scheme lb). lH NMR analysis of an aliquot of the reaction mixture indicates > 90% conversion to the terminal carbene 8, its isolation in pure form hampered by its high solubility and thermal sensitivity.

Scheme 1b. Synthesis of 8.

N=N=CPh2 [Me3NN]Cu(toluene) # [Me3NN]Cu=CPh2 -N2 8 The X-ray structure of 8 reveals a contracted Cu-C bond distance of 1. 834 (3) A relative to the dicopper carbene 3 (Figure 24). This Cu-C distance is consistent with multiple-bond character and 8 exhibits structural parameters similar to those of the related d Ni (0) carbene (tBu2PCH2CH2PBut2) M=CPh2 which has a Ni-C distance of 1. 836 (2) A.

See Mindiola, D. ; Hillhouse, G. L. J. Am. Chem. Soc. 2002,124, 9976. The Cu-C bond in 8 shorter than that (1.882 (3) A) found in a structurally characterized three-coordinate cationic copper (I) Fischer carbene [Cu{=CR1(OR2)}(MeCN)(OEt2)]+ (R1 = (E)-CH=CH-2- furyl ; R2 = menthyl) isolated by carbene transfer from a Cr complex. See Barluenga, J.; Lopez, L. A.; Lober, O. ; Tomas, M.; Garcia-Granda, S.; Alvarez-Rua, C.; Borge, J. Angew.

Chem. , Int. Ed. 2001,40, 3392. In addition, the Cu-C distance in 8 is shorter than found in three-coordinate (1.914 (4) -1.9938 (14) A) and two-coordinate (1. 850 (4) -1.9124 (16) A) N-heterocyclic copper (I) carbenes for which copper-carbene s-backbonding is expected to be less important. See Tulloch, A. A. D.; Danopoulos, A. A.; Kleinhenz, S.; Light, M. E.; Hursthouse, M. B.; Eastham, G. Organometallics 2001,20, 2027; Hu, X.; Castro- Rodriguez, I. ; Meyer, K. Organometallics 2003,22, 3016; Arnold, P. L.; Scarisbrick, A. C.; Blake, A. J.; Wilson, C. Chem. Commun. 2001,2340 ; Hu, X.; Castro-Rodriguez, I. ; Meyer, K. J. Am. Chem. Soc. 2003,125, 12237; Mankad, N. P.; Gray, T. G.; Laitar, D. S.; and Sadighi, J. P. Organometallics 2004,23, 1191; Hu, X.; Castro-Rodriguez, I.; Meyer, K.

Organometallics 2004,23, 755. Maximizing n-backbonding with the [Me3NN] Cu fragment, the carbene ligand in 8 is essentially orthogonal to the (3-diketiminate backbone (89. 0° twist angle). The 1H NMR spectrum of 8 in benzene-d6 exhibits Czv symmetry and the backbone C-H resonance at 8 4. 989 ppm has a similar chemical shift as that ascribed to [Me2NN] Cu=CPh2 (4) at 8 4.958 ppm. The carbene carbon resonates at 8 253.1 ppm in the 13C{H} NMR spectrum of 8, downfield of the carbene resonance in the bridged species 3 as well as Hofmann's terminal But2P (NSiMe3) 2-K2N] Cu=C (Ph) C (O) Me observed at 8 229.9 ppm, but within the approximate range 200-400 ppm established for terminal carbenes.

See Straub, B. F.; Hofmann, P. Angew. Chem. , Int. Ed. 2001,40, 1288; and Crabtree, R. H.

The Organometallic Chemistry of the Transition Metals; Wiley-Interscience : New York, 2001.

Kinetics Studies for Cyclopropanation of Styrene Derivatives by [Me3NN]Cu=CPh2 Terminal carbene 8 quickly reacts with styrene at room temperature to give 1,1, 2- triphenylcyclopropane and exhibits clean pseudo first-order kinetics in 1,4-dioxane in the presence of excess styrene (Table 2; Figures 18,19 and 25).

Table 2. Observed 1st order and actual 2nd order rate constants for styrene cyclopropanation by 8 under pseudo-first order conditions with [styrene] = 0. 0839 (2) M. kobs (s-1) 17.5 7.79 (5) x 10-9. 29 (6) # 10- 30.2 1.69 (5) x 10-2. 02 (6) x 10- 40. 5 2. 83 (5) x 10-3. 42 (6) x 10- 50.0 5.31 (5) x 10-6. 38 (6) x 10- 60.2 9.0 (1) x 10-3 1. 08 (2) x 10- Decomposition of LALe3NN7CU=CPh2 Dilute (ca. 0.8 mM) solutions of the terminal carbene 8 in 1,4-dioxane cleanly decompose in a first-order fashion to the carbene coupling product Ph2C=CPh2 and the solvated [Me3NN] Cu fragment. The first-order rate constants for decomposition obtained over temperature range 30-60 °C measured by W-vis spectroscopy (Table 3) are only 30 - 100 times lower than the actual second-order rate constants determined in the cyclopropanation of styrene at these temperatures. This comparison underscores the importance of excess alkene present under typical catalytic conditions dilute in copper catalyst to achieve clean cyclopropanation. Activation parameters SHi = 21 (1) kcal/mol

and AS =-8 (3) cal/mol'K reveal a significantly larger AW for carbene loss relative to transfer to styrene. This is to be expected as the breaking Cu-carbene bond is not compensated by C-C bond formation in the transition state and suggests a lower limit to the Cu-carbene bond strength.

Table 3. Observed 1st order rate constants for thermal decomposition of 8. T (°C) k (s-1) 32.2 1.92(5) # 10-5 40. 0 4.0 (1) x 10-" 49. 0 1.26 (5) X 10- 60. 0 3. 4 (1) x 10 In more concentrated arene solutions (40 mM), [Me3NN] Cu=CPh2 (8) decomposes to [Me3NN] Cu (arene) which combines with 8 still present to form an equilibrium concentration o f the dicopper carbene { [Me3NN] Cu} 2 (ll-CPh2). In b enzene-d6, this n ew species exhibits a backbone C-H 1H NMR resonance at 8 5. 018 ppm and its 13C {1H} NMR spectrum reveals a carbene signal at 8 189. 0 ppm, chemical shifts nearly identical to those observed for 3. Arene solutions of 8 still retain cyclopropanation activity after two days at room temperature as the more thermally stable dicopper carbene 9 becomes the predominant Cu-containing species after a few hours in solution.

Cyclopropanation Reactions While arene solutions of 3 show little decomposition at room temperature over 2 days, 3 reacts with 3 equiv. styrene in benzene-d6 within minutes to give 1, 1,2- triphenylcyclopropane and 2 eq. Cu-styrene complex [Me2NN] Cu (styrene) (Scheme 2). See Dai, X.; Warren, T. H. Chem. Commun. 2001,1998. The reactivity of 3 with substituted styrene derivatives is sensitive to the stereochemistry of the alkene; reaction of 3 with an 20-fold excess of a-methylstyrene gives clean conversion the cyclopropane while trans-p- methylstyrene only gives 40% conversion to cyclopropane with significant C2Ph4 production. A competition experiment involving 10 equiv. each of styrene and p- methoxystyrene results in a 2: 3 ratio of the corresponding cyclopropanes and suggests the presence of an electrophilic carbene intermediate. See Diaz-Requejo, M. M.; Perez, P. J.; Brookhart, M.; Templeton, J. L. Organometallics 1997,16, 4399. Since 3 also reacts with N2CPh2 to give the azine Ph2C=N-N=CPh2 (Scheme 2), cyclopropanation of styrene with

N2CPh2 catalyzed by 3 (formed from 2) requires slow addition of N2CPh2 to a toluene solution containing 10 equiv. styrene and 5 mol% 2 over 20 h and results in a 67% yield of cyclopropane with some azine formation (Scheme 4). In contrast to the (TPFPP) Os system, essentially no C2Ph4 (<1%) from coupling of the diphenylcarbene moieties is observed by GC/MS analysis. See Li, Y.; Huang, J. -S. ; Zhou, Z. -Y. ; Che, C. -M. J. Am. Chem. Soc.

2001,123, 4843.

Interestingly, it has been reported that benzophenone azine forms quantitatively upon addition of N2CPh2 to the discrete rhodium carbene Cp (Sb'Pr3) Rh=CPh2. See Werner, H.; Schwab, P. ; Bleuel, E.; Mahr, N.; Windmuller, B. ; Wolf, J. Chem. Eur. J. 2000,6, 4461.

This azine is also the primary product when N2CPh2 is added to Rh2 (OAc) 4, the prototypical member of an efficient family of rhodium (II) carboxylate and carboxamide catalysts for alkene cyclopropanation with a-carbonyl diazo reagents. See Shankar, B. K.

R.; Shechter, H. Tetrahedron Lett. 1982,23, 2277; and Doyle, M. P. Chem. Rev. 1986,86, 919; (b) Burke, S. D.; Grieco, P. A. Org. React. (N. Y. ) 1979,26, 361.

Scheiiie 4. Cyclopropanation of styrene catalyzed by 3. N=N=CHCOOEt Ph Ph ==\ mol% 2 Ph + or- toluene Ph We have established that styrene and its derivatives such as p-methoxystyrene and a-methylstyrene react with 3 when the alkene is in about 20-fold excess to give essentially quantitative transfer of the CPh2 fragment in 3 to form the corresponding cyclopropane while trans-p-methylstyrene gives only a 40% conversion to the cyclopropane with a significant (>50%) a mount o f P h2C=CPh2 t hat must r esult from the decomposition of 3.

Furthermore, cyclooctene gives a 28% cyclopropane yield under similar conditions.

However, results thus far indicate that 1-hexene gives the cyclopropane in low yield as a mixture of products.

We have also established that the neutral Cu (I) p-diketiminato complex (2) catalyzes the cyclopropanation of styrene with ethyl diazoacetate (EDA). Addition of EDA in o ne p ortion t o a t oluene s olution c ontaining 5 e quiv. s tyrene a nd 2 mol% 2 gave the corresponding cyclopropane in 77 % yield as a 38: 62 cisltrans mixture (Scheme 4).

One aspect of this invention is to develop stereoselective protocols for cyclopropanation o f alkenes w ith n on-heteroatom s tabilized d iazo r eagents. It i s known that diazo reagents N2CRR'that do not bear heteroatom containing oc-substituents are much more prone to catalytic dimerization to alkenes R'RC=CRR'by metal complexes than the heavily utilized diazo esters. See Tomilov, Y. V.; Dokichev, V. A. ; Dzhemilev, U. M.; Nefedov, O. M. Russ. Chem. Rev. 1993,62, 799; Oshina, T.; Nagai, T. Tetrahedron Lett.

1980,21, 1251; and Shankar, B. K. R. ; Shechter, H. Tetrahedron Lett. 1982, 23,2277.

Routes t o e nantiopure c ycloalkanes w ould c ertainly find u se i n p harmaceutical synthesis and the development of combinatorial libraries. Using monosubstituted diazo reagents such as N2CHPh in conjuction with a suitable precursor to the neutral [ß-diketiminate] Cu fragment, we will outline its cis l trans diastereoselectivity with monosubstituted alkenes such as styrenes. By steric variation of the ß-diketiminate-like supporting ligand (Scheme 5), it is reasonable to expect to be able to influence cis/trans diastereoselectivity. A representative list of potential non-chiral p-diketiminato complexes appears in Scheme 5.

Enantioselectivity will require the use of an enantiopure [ß-diketiminate-like] Cu complex.

Given their similarity to the successful [Me2NN] Cu (ethylene) system, a class of chiral copper (I) c omplexes b ased o n c hiral N, N' 1 igands i n S cheme 6 c ould b e p repared u sing synthetic methodology developed in our laboratories. See Bertilsson, S. K. ; Tedenborg, L. ; Alonso, D. A.; Andersson, P. G. Organometallics 1999,18, 1281-1286 ; Pfaltz, A. Acc.

Chem. Res. 1993,1993, 339-345; Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998, 98, 911- 935; and Lebel, H.; Marcoux, J. -F. ; Molinaro, C.; Charette, A. B. Chem. Rev. 2003, 103, 977-1050. Straigtforward variation of the substituents as outlined in Scheme 6 will allow a wide range of systems to be evaluated.

This Cu (I) system could also be used to stabilize carbenes derived from a wider range of diazo reagents. Furthermore, the unique bonding mode observed in the dicopper carbenes 3 and 12 suggests the use of two [P-diketiminato] Cu fragments in concert to stabilize other highly electrophilic functional groups such as nitrenes (NR) for related copper-catalyzed group transfer processes. For example, a disilver (I) complex has been recently reported to efficiently catalyze the aziridination of alkenes with PhI=NTs. See Cui, Y.; He, C. J. Am. Chem. Soc. 2003,125, 16202.

Scheme 5. Sample members of family of chiral Cu (I) P-diketiminate-like complexes other than [Me2NN] Cu (L) to be investigated.

R6 R5 ) R6 R'R'I I R'not necessarily equal to R3 = H, Me, Et,'Pr, F, Cl R\/Rl R2=H, Me, tBu, CF3 R Cu-L =Cl, CN, aryl \ : R5 = H, Me, tBu R2 3 R6 = H, Me, CF3, tBu R > > 3 L = neutral ligand such as : alkene, lutidine, arene R6 Rs Sclaerne 6. Sample members of family of chiral Cu (I) ß-diketiminate-like complexes to be investigated.. Razz I R6 Rl = H, Me, Et,'Pr, F, Cl Ri >/\ 3 R2 =H, Me, CF3 R'R'R = Me,'Pr,'Bu, Ph, C (O) OSiR'3 SN SN\ R4 = H, C1, CN R Cu-L R Cu-L R5=n, Me,'Bu R6 = H, Me, CF3, tBu 0 0 3 L = neutral ligand such as : alkene, lutidine, arene Preparation of Cobalt ß-Diketiminato Stabilized Catalysts Oxo (02-) and imido (NR2-) functionalities bound to later first row transition metals attract interest as active agents in atom and group transfer2 reactions to alkenes as well as in C-H bond functionalization. 3 Due to their important biological roles (especially for Fe), 4 such oxo complexes have commanded considerably more attention than isoelectronic imido counterparts. Despite cobalt's seminal role in synthetic metal-dioxygen chemistry, 5 species bearing oxo functionalities have been established only recently. The bulky tris (pyrazolyl) borates {Me3TpCo} 2 (µ-OH)2 react with H2O2 to provide {Me3TpCo} 2 (lu-0) 2 species that are susceptible to intramolecular C-H bond abstraction by the oxo ligand.

PrMeTpCo}2(µ-N2) directly reduces O2 by 4 electrons to produce a related, but especially thermally sensitive bis(µ-oxo)dicobalt(III) complex.7,8 Furthermore, a square-planar

02 (-0) 2 species was isolated in the disproportionation of the Co (II) complex [Co (H2L) 2] 2- (H2L = bis [(t-butyl) aminocarbonyl]-1, 2-diamidoethane) in the presence of O2.9 Imido functionalities bound to later first row metals are beginning to exhibit reactivity patterns reminiscent of oxo species. For instance, Theopold observed intramolecular C-H bond abstraction by inferred Tp"Co=NTMS intermediates in the reaction of Tp"Co (N2) with N3TMS. 1° Peters has shown that tris (phosphino) borate complexes [P3B] M=N (p-tolyl) (M = Fe, lla Collb) undergo imido group transfer to CO providingp-tolylNCO. Exploring relationships between oxo and imido functionalities in later, first row chemistry, we describe herein the synthesis of a p-diketiminato Co (I) arene adduct and its reactivity with dioxygen, organoazides, and a nitrosobenzene to provide a family of structurally diverse oxo and imido complexes. l2 The paramagnetic, tetrahedral Co (II) 8-diketiminatel3 [Me2NN] Co (I) (2,4-lutidine) (6) may be prepared in 90% yield from reaction of Tl [Me2NN] l4 with CoI2 (2,4-lutidine) 2 as teal crystals. Reduction of this species with Mg powder in toluene provides air-sensitive, red crystals of [Me2NN] Co (n6-toluene) (7) in 60-70% yield on a gram scale (Scheme 7).

This d8 Co (arene adduct is high-spin as evidenced by its room temperature magnetic moment of 2.7 B. M. in toluene-d8. While diamagnetic [Me2NN] Rh (arene) and {[Me2NN] Rh} 2 (arene) complexes favor 4-arene coordination, 15 the X-ray structure of 10 reveals an 116_ toluene ligand (Co-C = 2.207 (6) -2.288 (5) A) bound to the [Me2NN] Co fragment (Scheme 7).

Addition of several equivalents of dry oxygen to 10 in ether at room temperature results in an immediate color change from red to violet signaling the formation of {[Me2NN] Co} 2 (ll-0) 2 (11) that may be isolated in 75% yield as maroon crystals (Scheme 7). The X-ray structure of 11 obtained at-90 °C consists of two [Me2NN] Co fragments related by inversion separated by 2.716 (4) A. Final refinement suggested positional disorder for the bridging oxygen atoms. The predominant orientation (86% occupancy; Figure 6) consists of oxo atoms related by inversion that appear in roughly square planar sites9 (22. 2° and 23. 0° twist angles between the N-Co-N and Ol-Co-Ol'planes) with nearly identical Co-Ol and Co-Ol'bond distances of 1. 784 (3) and 1.793 (4) A. The minor orientation consists of two inequivalent oxo atoms that symmetrically bridge in a tetrahedral disposition and exhibit somewhat lengthened Co-O distances. l6 The short metal-metal and metal-oxo distances found in 11 compare favorably to those in related "diamond core"M2 (11-O) 2 (M = Fe-Cu) structures. 3C 9 Scheme 7. Synthesis, structure, and reactivity of 10 <BR> <BR> <BR> Tl [Me2NN] xs Mg<BR> CoI2(lut)2 # [Me2NN]CoI(lut) # [Me2NN]Co(#@-tol)<BR> -T1I -MgI2<BR> 9 10<BR> <BR> <BR> <BR> -2,4-lut -2,4-lut

While toluene-d8 solutions of 11 exhibit sharp lu NMR signals from-75 to +80 °C, the p-diketiminate resonances become contact shifted toward higher field with increasing temperature. For instance, the backbone C-H and Ar-Me resonances shift from 8 6.1 and 0.5 ppm to 5-3. 5 and-3.0 ppm, respectively. Over this temperature range, the solution magnetic moment of 11 in toluene-d8 increases from 3.9 to 4.3 B. M. This reversible behavior suggests that the d6 Co (III) centers in 11 are antiferromagnetically coupled; a detailed magnetic investigation of 11 is underway.

Aiming to prepare related imido complexes, we explored the reactivity of 10 with organoazides (Scheme 1). Reaction of 7 with N3Ar (Ar = 3, 5-Me2C6H3) in ether results in rapid effervescence and formation of the tetrahedral Co (III)-imido bridged dimer {[Me2NN] Co} 2 (ll-NAr) 2 (12). Its solution magnetic moment of 8. 8 B. M. in benzene-d6 at RT indicates the presence of two fully high-spin, ferromagnetically coupled d6 centers. The X-ray structure of 12 (Figure 1) exhibits a considerably longer Co-Co separation (3.067 (3) A) than found in 11 with Co-N (imido) bond distances of 1. 983 (3) and 1. 988 (3) A. In contrast, reaction of 10 with the more sterically demanding N3Ad (Ad = 1-adamantyl) leads to the formation of the three-coordinate terminal imide [Me2NNlCo=-NAd (14) that may be isolated in 50% yield as red crystals. The X-ray structure of 14 (Figure 9) reveals a Co- N (imide) bond distance of 1.624 (4) A which is at the short end of the range 1.64-1. 70 A

observed in sparse examples of Fe, ll l7 Co, l2 and Ni'8 terminal imides. Though in the solid state the imido substituent is somewhat bent (Co-N3-C22 = 161.5 (3) °) toward the opposite side of the trigonal plane formed by the three N-donors from which the Co center is slightly (0.169 A) displaced, diamagnetic 13 exhibits C2v-symmetric lH and 13C NMR spectra in benzene-d6 at RT. This low-spin d6 configuration in 13 would allow s-donation of the two orthogonal lone pairs of an sp-hybridized imido N-atom into two empty metal d orbitals destabilized by a-and a-interactions with the p-diketiminate N-donor atoms. Preliminary DFT calculations support this simple orbital picture that predicts considerable metal-imido multiple bond character in 13 and allows its formulation as a 16-electron species.

To explore the generality of 10 as a precursor to oxo and imido species via reductive cleavage of double bonds to O and N, we exposed 10 to 0.5 equiv. of O=NAr (Ar = 3,5- Me2C6H3) in ether which results in the formation of the binuclear {[Me2NN] Co} 2 (z-O) (p- NAr) (14) in 33% isolated yield (Scheme 1). This 4 electron reduction of a nitrosobenzene stands in contrast to the reaction of the related CpCo (C2H4) 2 with O=NPh which leads to [CpCo] 2 (p-P2 : l-PhNO) 2. 19 The X-ray structure of 14 (Figure 10) is intermediate between the structures observed for the square-planar bis (p-oxo) 11 and tetrahedral bis (p-imido) 12 with opposing [Me2NN] Co fragments that are nearly orthogonal (89. 2° twist angle). While the Co-Co separation (2.7420 (6) A) and Co-O distances (1.783 (2) and 1. 786 (2) A) in 14 are similar to those found in the square planar bis (p-oxo) 11, the Co-N distances (1. 821 (3) and 1. 823 (3) A) lie between those in the tetrahedral bis (µ-imido) 12 and terminal imido 13.

Furthermore, 14 possesses a non-temperature dependent solution magnetic moment of 4.9 B. M. that falls between that observed for 11 and 12.

In summary, [Me2NN] Co (n6-toluene) (7) serves as a synthon to the 12-electron, two-coordinate [Me2NN] Co fragment that cleaves O=O, N=N, and O N bonds to provide a family of structurally diverse Co (III) oxo and imido species. Subsequent reports will detail their magnetic behavior and reactivity patterns. For instance, the M=NR bond of terminal 13 undergoes ready cycloaddition reactions with organoazides and isocyanates. Given the thermal stability of both bis (µ-oxo) 11 and terminal imido 13, a monomeric Co (III) oxo complex may be a viable synthetic target.

References for Preparation of Cobalt i-Diketiminato Stabilized Catalsts (1) (a) Palucki, M.; Finney, N. S.; Pospisil, P. J.; Guler, M. L.; Ishida, T.; Jacobsen, E.

N. J. Am. Chem. Soc. 1998,120, 948. (b) Groves, J. T.; Lee, J.; Marla, S. S. J. Am. Chem.

Soc. 1997,119, 6269. (c) Collman, J. P.; Wang, Z.; Straumanis, A.; Quelquejeu, M. J. Am.

Chem. Soc. 1999,121, 460. (d) Feichtinger, D.; Plattner, D. A. Chem. Eur. J. 2001,7, 591.

(2) (a) Groves, J. T.; Takahashi, T. J. Am. Chem. Soc. 1983,105, 2073. (b) DuBois, J.

L.; Tomooka, C. S.; Hong, J.; Carreira, E. M. Ace. Chem. Res. 1997,30, 364. (c) Li, Z. ; Quan, R. W.; Jacobsen, E. N. J. Am. Chem. Soc. 1995,117, 5889. (d) Brandt, P.; Södergren, M. J.; Andersson, P. G.; Norrby, P.-O. J. Am. Chem. Soc. 2000, 122, 8013. (e) Au, S. -M. ; Huang, J. -S. ; Yu, W. -Y. ; Fung, W. -H. ; Chi, C. -M. J. Am. Chem. Soc. 1999, 121,9120. (f) Wigley, D. E. Prog. Inorg. Chem. 1994,42, 239. (g) Mansuy, D.; Mahy, J.- P. ; Dureault, A.; Bedi, G.; Battioni, P. J. Chem. Soc. , Chem. Commun. 1984, 1161.

(3) (a) Chen, K.; L Que, J. J. Am. Chem. Soc. 2001,123, 6327. (b) Collman, J. P.; Chien, A. S.; Eberspacher, T. A.; Brauman, J. I. J. Am. Chem. Soc. 1998,120, 425. (c) Que, Jr. , L.; Tolman, W. B. Angew. Chem. Int. Ed. 2002,41, 1114-1137 and references within.

(4) (a) Sono, M.; Roach, M. P. ; Coulter, E. D.; Dawson, J. H. Chem. Rev. 1996,96, 2841. (b) Solomon, E. I. ; Brunold, T. C.; Davis, M. I.; Kemsley, J. N. ; Lee, S.-K. ; Lehnert, N. ; Neese, F.; Skulan, A. J.; Yang, Y. -S. ; Zhou, J. Chem. Rev. 2000, 100, 235. (c) Cyctochrome P-450: Structure, Mechanism, and Biochemistry; de Montellano, P. R. O., Ed.; Plenum : New York, 1985. (d) Manchmda, R. ; Brudvig, G. W. ; Crabtree, R. H. Coord.

Chem. Rev. 1995,144, 1. (e) Feig, A. L. ; Lippard, S. J. Chem. Rev. 1994,94, 759.

(5) Bianchini, C.; Zoellner, R. W. Adv. Inorg. Chem. 1996,44, 263.

(6) (a) Hikichi, S.; Akita, M.; Moro-oka, Y. Coord. Chem. Rev. 2000,198, 61. (b) Hikichi, S.; Yoshizawa, M.; Sasakura, Y.; Akita, M.; Moro-oka, Y. J. Am. Chem. Soc.

1998,120, 10567.

(7) Hikichi, S.; Yoshizawa, M.; Sasakura, Y.; Komatsuzaki, H.; Moro-oka, Y.; Akita, M. Chem. Eur. J. 2001,7, 5012.

(8) (a) Reinaud, O. M.; Theopold, K. H. J. Am. Chem. Soc. 1994,116, 6979. (b) Theopold, K. H.; Reinaud, O. M.; Doren, D.; Konecny, R. In 3rd World Congress on Oxidation Catalysis; Grasselli, R. K. , Oyama, S. T., Gaffney, A. M. , Lyons, J. E. , Eds.; Elsevier: Amsterdam, 1997, p 1081.

(9) Larsen, P. L.; Parolin, T. J.; Powell, D. R.; Hendrich, M. P.; Borovik, A. S. Angew.

Chem. Int. Ed. 2003,42, 85.

(10) Thyagarajan, S.; Shay, D. T.; Incarvito, C. D. ; Rheingold, A. L.; Theopold, K. H. J.

Am. Chem. Soc. 2003,125, 4440.

(11) (a) Brown, S. D. ; Betley, T. A.; Peters, J. C. J. Am. Chem. Soc. 2003,125, 322. (b) Jenkins, D. M.; Betley, T. A.; Peters, J. C. J. Am. Chem. Soc. 2002,124, 11238.

(12) Some of this work has been presented: Dai, X.; Warren, T. H. , Abstracts of Papers, 224st National Meeting of the American Chemical Society, Boston, MA, August 18-22, 2001, No. INOR 407.

(13) Related, bulkier three-and four-coordinate Co (II) b-diketiminates have been recently reported: Holland, P. L.; Cundari, T. R.; Perez, L. L.; Eckert, N. A.; Lachicotte, R.

J. J. Am. Chem. Soc. 2002,124, 14416.

(14) Dai, X. ; Warren, T. H. Chem. Commun. 2001, 1998.

(15) Budzelaar, P. H. M.; Moonen, N. N. P.; de Gelder, R.; Smits, J. M. M. ; Gal, A. W.

Chem. Eur. J. 2000,6, 2740.

(16) See Figures for refinement details and ORTEP diagram.

(17) Verma, A. K. ; Nazif, T. N.; Achim, C.; Lee, S. C. J. Am. Chem. Soc. 2000,122, 11013.

(18) (a) Mindiola, D. J.; Hillhouse, G. L. J. Am. Chem. Soc. 2001, 123,4623. (b) Kogut, E.; Wiencko, H. L.; Zhang, L.; Warren, T. H. manuscript in preparation.

(19) Stella, S.; Floriani, C.; Chiesi-Villa, A.; Guastini, C. J. Chem. Soc. , Dalton Trans.

1988,545.

Deflizitions For convenience, certain terms employed in the specification, examples, and appended claims are collected here.

The articles"a"and"an"are used herein to refer to one or to more than one (i. e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 67th Ed. , 1986-87, inside cover.

A"stereoselective process"is one which produces a particular stereoisomer of a reaction product in preference to other possible stereoisomers of that product. An "enantioselective process"is one which favors production of one of the two possible enantiomers of a reaction product. The subject method is said to produce a "stereoselectively-enriched"product (e. g. , enantioselectively-enriched or diastereoselectively-enriched) when the yield of a particular stereoisomer of the product is greater by a statistically significant amount relative to the yield of that stereoisomer resulting from the same reaction run in the absence of a chiral catalyst. For example, an enantioselective reaction catalyzed by one of the subject chiral catalysts will yield an e. e. for a particular enantiomer that is larger than the e. e. of the reaction lacking the chiral catalyst.

The term"reaction product"means a compound which results from the reaction of the catalyst and the alkene substrate. In general, the term"reaction product"will be used herein to refer to a stable, isolable compound, and not to unstable intermediates or transition states.

The term"catalytic amounts recognized in the art and means a substoichiometric amount relative to a reactant. As used herein, a catalytic amount means from 0.0001 to 90 mole percent relative to a reactant, more preferably from 0.001 to 50 mole percent, still more preferably from 0. 01 to 10 mole percent, and even more preferably from 0.1 to 5 mole percent relative to a reactant.

As discussed more fully below, the reactions contemplated in the present invention include reactions which are enantioselective, diastereoselective, and/or regioselective. An enantioselective reaction is a reaction which converts an achiral reactant to a chiral product enriched in one enantiomer. Enantioselectivity is generally quantified as"enantiomeric excess" (ee) defined as follows: % Enantiomeric Excess A (ee) = (% Enantiomer A) - (% Enantiomer B) where A and B are the enantiomers formed. Additional terms that are used in conjunction with enatioselectivity include"optical purity"or"optical activity". An enantioselective reaction yields a product with an e. e. greater than zero. Preferred enantioselective reactions yield a product with an e. e. greater than 20%, more preferably greater than 50%, even more preferably greater than 70%, and most preferably greater than 80%.

A diastereoselective reaction converts a chiral reactant (which may be racemic or enantiomerically pure) to a product enriched in one diastereomer. If the chiral reactant is racemic, in the presence of a chiral non-racemic reagent or catalyst, one reactant enantiomer may react more slowly than the other. This class of reaction is termed a kinetic resolution,

wherein the reactant enantiomers are resolved by differential reaction rate to yield both enantiomerically-enriched product and enantimerically-enriched unreacted substrate.

Kinetic resolution is usually achieved by the use of sufficient reagent to react with only one reactant enantiomer (i. e. , one-half mole of reagent per mole of racemic substrate).

Examples of catalytic reactions which have been used for kinetic resolution of racemic reactants include the Sharpless epoxidation and the Noyori hydrogenation.

The term"non-racemic"with respect to the chiral catalyst, means a preparation of catalyst having greater than 50% of a given enantiomer, more preferably at least 75%.

"Substantially non-racemic"refers to preparations of the catalyst which have greater than 90% ee for a given enantiomer of the catalyst, more preferably greater than 95% ee.

The term"allcyl"refers to the radical of saturated aliphatic groups, including straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups. In preferred embodiments, a straight chain or branched chain alkyl has 30 or fewer carbon atoms in its backbone (e. g., C1-C30 for straight chain, C3-C30 for branched chain), and more preferably 20 of fewer. Likewise, preferred cycloalkyls have from 4-10 carbon atoms in their ring structure, and more preferably have 5,6 or 7 carbons in the ring structure.

Unless the number of carbons is otherwise specified,"lower alkyl"as used herein means an alkyl group, as defined above, but having from one to ten carbons, more preferably from one to six carbon atoms in its backbone structure. Likewise,"lower alkenyl"and"lower alkynyl"have similar chain lengths.

The terms"alkenyl"and"alkynyl"refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but which contain at least one double or triple carbon-carbon bond, respectively.

The term"Me2NN"refers to a moiety represented by the general formula: As used herein, the term"amino"means-NH2 ; the term"nitro"means-NO2 ; the term"halogen"designates-F,-Cl,-Br or-I ; the term"thiol"means-SH; the term "hydroxyl"means-OH; the term"sulfonyl"means-S02- ; and the term"organometallic"

refers to a metallic atom (such as mercury, zinc, lead, magnesium or lithium) or a metalloid (such as silicon, arsenic or selenium) which is bonded directly to a carbon atom, such as a diphenylmethylsilyl group.

The terms"amine"and"amino"are art-recognized and refer to both unsubstituted and substituted amines, e. g. , a moiety that can be represented by the general formula: wherein Rg, Rlo and R'l0 each independently represent a group permitted by the rules of valence.

The term"acylamino"is art-recognized and refers to a moiety that can be represented by the general formula: wherein Rg is as defined above, and R'll represents a hydrogen, an alkyl, an alkenyl or - (CH2) m-Rg, where m and Rg are as defined above.

The term"amido"is art-recognized as an amino-substituted carbonyl and includes a moiety that can be represented by the general formula: wherein Rg, RIO are as defined above. Preferred embodiments of the amide will not include imides which may be unstable.

The term"alkylthio"refers to an alkyl group, as defined above, having a sulfur radical attached thereto. In preferred embodiments, the"alkylthio"moiety is represented by one of-S-alkyl,-S-alkenyl,-S-alkynyl, and-S-(CH2) m-Rg, wherein m and R8 are defined above. Representative alkylthio groups include methylthio, ethyl thio, and the like.

The term"carbonyl"is art-recognized and includes such moieties as can be represented by the general formula: wherein X is a bond or represents an oxygen or a sulfur, and R11 represents a hydrogen, an alkyl, an alkenyl, -(CH2)m-R8 or a pharmaceutically acceptable salt, R ! l 1 represents a hydrogen, an alkyl, an alkenyl or- (CH2) m-Rg, where m and R8 are as defined above.

Where X is an oxygen and Rl 1 or R'1 1 is not hydrogen, the formula represents an"ester".

Where X is an oxygen, and Rl 1 is as defined above, the moiety is referred to herein as a carboxyl group, and particularly when Rl 1 is a hydrogen, the formula represents a "carboxylic acid". Where X is an oxygen, and R'l 1 is hydrogen, the formula represents a "formate". In general, where the oxygen atom of the above formula is replaced by sulfur, the formula represents a"thiolcarbonyl"group. Where X is a sulfur and R1 l or R'1 1 is not hydrogen, the formula represents a"thiolester."Where X is a sulfur and Rn is hydrogen, the formula represents a"thiolcarboxylic acid."Where X is a sulfur and Rll'is hydrogen, the formula represents a"thiolformate."On the other hand, where X is a bond, and R1 1 is not hydrogen, the above formula represents a"ketone"group. Where X is a bond, and Rl 1 is hydrogen, the above formula represents an"aldehyde"group.

The terms"alkoxyl"or"alkoxy"as used herein refers to an alkyl group, as defined above, having an oxygen radical attached thereto. Representative alkoxyl groups include methoxy, ethoxy, propyloxy, tert-butoxy and the like. An"ether"is two hydrocarbons covalently linked by an oxygen. Accordingly, the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxyl, such as can be represented by one of-O-alkyl,-O- alkenyl,-O-alkynyl,-O-(CH2) m-Rg, where m and R8 are described above.

The term"sulfonate"is art-recognized afid includes a moiety that can be represented by the general formula:

in which R41 is an electron pair, hydrogen, alkyl, cycloalkyl, or aryl.

The term"sulfonylamino"is art-recognized and includes a moiety that can be represented by the general formula : The term"sulfamoyl"is art-recognized and includes a moiety that can be represented by the general formula: The term"sulfonyl", as used herein, refers to a moiety that can be represented by the general formula : in which R44 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclyl, aryl, or heteroaryl.

The term"sulfoxido"as used herein, refers to a moiety that can be represented by the general formula:

in which R44 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclyl, aralkyl, or aryl.

The term"sulfate", as used herein, means a sulfonyl group, as defined above, attached to two hydroxy or alkoxy groups. Thus, in a preferred embodiment, a sulfate has the structure: u in which R40 and R41 are independently absent, a hydrogen, an alkyl, or an aryl. Furthermore, 1t40 and R41, taken together with the sulfonyl group and the oxygen atoms to which they are attached, may form a ring structure having from 5 to 10 members.

Analogous substitutions can be made to alkenyl and alkynyl groups to produce, for example, alkenylamines, alkynylamines, alkenylamides, alkynylamides, alkenylimines, alkynylimines, thioalkenyls, thioalkynyls, carbonyl-substituted alkenyls or alkynyls, alkenoxyls, alkynoxyls, metalloalkenyls and metalloalkynyls.

The term"aryl"as used herein includes 4-, 5-, 6-and 7-membered single-ring aromatic groups which may include from zero to four heteroatoms, for example, benzene, naphthalene, anthracene, pyrene, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyridazin and pyrimidine, and the like. Those aryl groups having heteroatoms in the ring structure may also be referred to as"aryl heterocycle". The aromatic ring can be substituted at one or more ring positions with such substituents as described above, as for example, halogens, alkyls, alkenyls, alkynyls, hydroxyl, amino, nitro, thiol amines, imines, amides, phosphonates, phosphines, carbonyls, carboxyls, silyls, ethers, thioethers, sulfonyl, selenoethers, ketones, aldehydes, esters, or- (CH2) m-R7,-CF3,-CN, or the like.

The terms"heterocycle"or"heterocyclic group"refer to 4 to 10-membered ring structures, more preferably 5 to 7 membered rings, which ring structures include one to four

heteroatoms. Heterocyclic groups include pyrrolidine, oxolane, thiolane, imidazole, oxazole, piperidine, piperazine, morpholine. The heterocyclic ring can be substituted at one or more positions with such substituents as described above, as for example, halogens, alkyls, alkenyls, alkyls, hydroxyl, amino, nitro, thiol, amines, imines, amides, phosphonates, phosphines, carbonyls, carboxyls, silyls, ethers, thioethers, sulfonyl, selenoethers, ketones, aldehydes, esters, or-(CH2) m-R7,-CF3,-CN, or the like.

The term"heteroatom"as used herein means an atom of any element other than carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, sulfur, phosphorus and selenium.

The terms ortho, iiieta and para apply to 1,2-, 1, 3- and 1,4-disubstituted benzenes, respectively. For example, the names 1,2-dimethylbenzene and ortho-dimethylbenzene are synonymous.

As used herein, the term"substituted"is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described hereinabove. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valencies of the heteroatoms. This invention is not intended to be limited in any manner by the permissible substituents of organic compounds.

Compounds of the Inve7ltion One aspect of the present invention relates to a compound represented by formula I : wherein,

Rl represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, or-CF3 ; R2 represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN,-CF3, 0-alkyl, or 0-aryl ; R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring; R represents independently for each occurrence H, alkyl, aryl, aralkyl, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aryloxycarbonyl, aminocarbonyl, or nitrile; and M is Cu or Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Zizis H or alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R4 represents independently for each occurrence H or aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R4 is phenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu, Rl is H, R is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu, Rl is H, R2 is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu, Ru ils H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Cu, Rl is H, R2 is methyl, R3 is 2, 6-dimethylphenyl, and R4 is phenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, R1 is H, R2 is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Ru ils H, R2 is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R is phenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein said compound is chiral.

Another aspect of the present invention relates to a compound represented by formula II : wherein, Rl is H, alkyl, aryl, aralkyl, halogen, -CN, or-CF3 ; R2 represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, -CF3, 0-alkyl, or 0-aryl ;

R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring; M is Cu or Co; and Y is an amine, =N-alkyl, N-cycloalkyl, =N-aryl, or 6-aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Rl is H or alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Y is 6-aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Ru ils H, R2 is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2, 6-dimethylphenyl, and Y is an amine.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and Y is lutidine.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and Y is =N- cycloalkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and Y is =N- adamantyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and Y is T16 aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and Y is 116 toluene.

In certain embodiments, the present invention relates to the aforementioned compound, wherein said compound is chiral.

Another aspect of the present invention relates to a compound represented by formula III: wherein, R'represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, or-CF3 ; R represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, -CF3, 0-alkyl, or O-aryl ; R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of W and R3 may be optionally linked by a covalent bond to form a ring; R4 is independently for each occurrence aryl; and M is independently for each occurrence Cu or Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Rl is H or alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein said compound is chiral.

Another aspect of the present invention relates to a compound represented by formula IV : IV wherein, Rl represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, or-CF3 ; R represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, -CF3, 0-alkyl, or O-aryl ; R3 represents independently for each occurrence alkyl or aryl ; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring;

R4 is aryl; and M is independently for each occurrence Cu or Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Rl is H or alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Ru ils H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, R'is H, R2 is methyl, and W is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein said compound is chiral.

Another aspect of the present invention relates to a compound represented by formula V:

wherein, Rl represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, or-CF3 ; R2 represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, -CF3, 0-alkyl, or 0-aryl ; R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring ; and M is independently for each occurrence Cu or Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co.

In certain embodiments, the present invention relates to the aforementioned compound, wherein Rl is H or alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Ri is H, W is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein M is Co, Rl is H, R2 is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned compound, wherein said compound is chiral.

Method of Preparing ß-Diketiminato Compounds of the Invention One aspect of the present invention relates to a method of preparing p-diketiminato compounds as depicted in Scheme 8:

Scheme 8 wherein, R'is H, alkyl, aryl, aralkyl, halogen, -CN, or-CF3 ; R2 represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN,-CF3, 0-alkyl, or 0-aryl ; R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring; R4 represents independently for each occurrence H, alkyl, aryl, aralkyl, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aryloxycarbonyl, aminocarbonyl, or nitrile; M is Cu or Co; and ligand is an alkene, arene, or amine.

In certain embodiments, the present invention relates to the aforementioned method, wherein said ligand is an alkene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said ligand is an ethylene.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu.

In certain embodiments, the present invention relates to the aforementioned method, wherein Rl is H or alkyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R4 represents independently for each occurrence H or aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R4 is phenyl In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, R2 is methyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, W is methyl, and R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, W is methyl, and R3 is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, W is methyl, R3 is 2,6-dimethylphenyl, and R4 is phenyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rl is H, R2 is methyl, R3 is 2, 6-dimethylphenyl, R4 is phenyl, and said ligand is ethylene.

Method of Synthesizing Cyclopropanes Using ß-Diketiminato Compounds One aspect of the present invention relates to a method of preparing a cyclopropane using p-diketiminato compounds, comprising the step of : reacting an alkene with a compound of formula I to give a cyclopropane product wherein, Ri represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, or-CF3; R2 represents independently for each occurrence H, alkyl, aryl, aralkyl, halogen, - CN, -CF3, 0-alkyl, or 0-aryl ;

R3 represents independently for each occurrence alkyl or aryl; wherein an occurrence of R2 and R3 may be optionally linked by a covalent bond to form a ring; R4 represents independently for each occurrence H, alkyl, aryl, aralkyl, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aryloxycarbonyl, aminocarbonyl, or nitrile ; and M is independently for each occurrence Cu or Co.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu.

In certain embodiments, the present invention relates to the aforementioned method, wherein Rlis H or alkyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R2 is alkyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R3 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R4 represents independently for each occurrence H or aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein R4 is phenyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, R1 is H, and W is methyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rlis H, R2 is methyl, and R3is 2,6-dimethylphenyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rlis H, R2 is methyl, R3 is 2,6-dimethylphenyl, and R4 is aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Rlis H, R2is methyl, R3is 2,6-dimethylphenyl, and Rois phenyl.

In certain embodiments, the present invention relates to the aforementioned method, wherein M is Cu, Ru ils H, R2is methyl, R3is 2,6-dimethylphenyl, R4 is phenyl, and said alkene is an optionally substituted styrene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said alkene is monosubstituted, disubstituted or trisubstituted.

In certain embodiments, the present invention relates to the aforementioned method, wherein said alkene is monosubstituted.

In certain embodiments, the present invention relates to the aforementioned method, wherein said alkene is (R5) 2C=C (rus), wherein RS represents independently for each occurrence hydrogen, allcyl, aryl, halogen, alkynyl, alkoxyl, silyloxy, amino, nitro, amide, phosphonate, phosphine, carbonyl, carboxyl, silyl, ether, thioether, sulfonyl, selenoether, ketone, aldehyde, or ester; In certain embodiments, the present invention relates to the aforementioned method, wherein said alkene is (R5) 2C=C (R5), wherein R5 represents independently for each occurrence hydrogen, alkyl, or aryl.

In certain embodiments, the present invention relates to the aforementioned method, wherein said alkene is an optionally substituted styrene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said compound of formula I is present in less than 25 mol% relative the alkene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said compound of formula I is present in less than 10 mol% relative the alkene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said compound of formula I is present in less than 5 mol% relative the alkene.

In certain embodiments, the present invention relates to the aforementioned method, wherein said compound of formula I is chiral.

In certain embodiments, the present invention relates to the aforementioned method, wherein said cyclopropane product is formed with an enantiomeric excess of greater than about 50%. hi certain embodiments, the present invention relates to the aforementioned method, wherein said cyclopropane product is formed with an enantiomeric excess of greater than about 75%.

In certain embodiments, the present invention relates to the aforementioned method, wherein said cyclopropane product is formed with an enantiomeric excess of greater than about 90%.

In certain embodiments, the present invention relates to the aforementioned method, wherein said cyclopropane product is formed with an enantiomeric excess of greater than about 95%.

Exemplification The invention now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention.

General Experimental Details All experiments were carried out in a dry nitrogen atmosphere using glovebox and standard Schlenk line techniques when required. 4A molecular sieves were activated at 180 °C in vacuo for 24 h. Anhydrous toluene and 1,4-dioxane were purchased from Aldrich and stored over 4A molecular sieves prior to use. Diethyl ether, tetrahydrofuran (THF), hexane, and pentane were distilled before use from sodium/benzophenone. All deuterated solvents were sparged with nitrogen, dried with 4A molecular sieves and stored under nitrogen. 1H and 13C spectra were recorded on a Mercury Varian 300 NMR spectrometer at 300 and 75.4 MHz, respectively. All NMR spectra were taken at 25 °C unless otherwise noted and were indirectly referenced to TMS using residual solvent signals as internal standards. GC-MS spectra were recorded on a Fisions Instruments MD800. Infrared spectra were recorded on a Perkin-Elmer Spectrum One FTIR spectrometer using an attenuated internal reflectance sample holder. Elemental analyses were performed on a Perkin-Elmer PE2400 microanalyzer in our laboratories.

Anhydrous CuBr was obtained from Strem and used as received. Styrene was obtained from Aldrich and passed through activated A1203 before use. Tl [Me2NN], [Me2NN] Cu (ethylene), diphenyldiazomethane, and 3, 5-dimethylphenylazide were synthesized according to literature procedures. See Dai, X.; Warren, T. H. Chem. Commun.

2001,198-199 ; Smith, P. A. S.; Brown, B. B. J. Am. Chem. Soc. 1951,23, 2438; and Smith, L. I. ; Howard, K. L. Organic Synthesis Collective, Vol. 3,1955, 351. Anhydrous CoI2 and 1-adamantylazide were obtained from Strem while Mg powder, 3,5-dimethylaniline and 2,4-lutidine were obtained from Aldrich ; all were used as received. 02 gas (99.5%) was obtained from MG Industries and passed through a drying tube containing CaCl2 prior to use.

Example 1 Catalytic cyclopropanation of styrene and EDA by [Me2NN] Cu (ethylene) (2). EDA (0. 28 mg, 2.211 mmol) (commercial sample contained ca. 10% CH2C12) was added to a solution of [Me2NN] Cu (ethylene) (0.017g, 0.044 mmol) and styrene (1.150 g, 11.06 mmol) in 5 mL toluene, the mixture was stirred for 2h, and naphthalene (0.195 g) was added as an internal standard and an aliquot of the resulting solution was diluted and analyzed by GC- MS to give a 76.9 % yield of 1-ethoxycarbonyl-2-phenyl-cyclopropane with diastereoselectivity of cisltra7ts # 38/62. The trans isomer was isolated and characterized by 1H NMR which was consistent with literature data.

Exarntple 2 Catalytic cyclopropanation of styrene and N2CPll2 by [Me2NN] Cu (ethylene) (2). To a solution of [Me2NN] Cu (ethylene) (0. 015g, 0.038 mmol) and styrene (0.780 g, 7.50 mmol) in 10 mL toluene, a solution of N2CPh2 (0.165 g, 0.757 mmol) in 9 mL of toluene was added by syringe pump at room temperature over a period of 20 h. After stirring at RT for another 6 h, naphthalene (0.112 g) was added as an internal standard and an aliquot of the resulting s olution w as p assed through s ilica g el and analyzed b y G C-MS t o g ive a 6 8% yield of 1, 1, 2-triphenylcyclopropane along with the azine Ph2C=N-N=CPh2 in ca. 30% yield.

Exaninle 3 Preparation of { [Me2NN] Cu} 2 ()-t-CPh2) (3) A cooled (-35 °C) solution of N2CPh2 (0. 074 g, 0.34 mmol) in 3 mL of toluene was added with stirring to a cooled (-35 °C) solution of [Me2NN] Cu (ethylene) (0.268 g, 0. 675 mmol) in 5 mL toluene. The color of solution turned dark purple immediately and effervescence was observed. After stirring at room temperature for 3 min, the reaction mixture was placed into the freezer and allowed to stand overnight. The volatiles were removed in vacuo and the residue was extracted with ether (10 mL) and filtered through Celite. The filtrate was concentrated and allowed to stand at- 35 °C. Darlc pmple crystals which had formed were collected on a frit, washed with cold ether, and dried in vacuo to afford 0.122 g (40.3%) of product as a 1: 1 ether solvate.

Recrystallization from hexane afforded crystals of 3 0. 75 hexane suitable for X-ray diffraction. 1H NMR (toluene-d8,-70 °C) : 8 7.3-6. 4 (m, 20, Ar), 6.16 (d, 2, o-CPh2), 5. 010 (s, 2, backbone-CH), 2.951 (s, 6, Ar-CII3), 1.953 (s, 6, Ar-CH3), 1.920 (s, 6, Ar-CH3), 1.639

(s, 6, backbone-CH3), 1.565 (s, 6, baclcbone-CH3), 1.213 (s, 6, Ar-CH3) ; 13C{1H} NMR (toluene-d8, -70 °C) : 8 189.41 (CPh2), 162.75 (imine), 161.18 (imine), 152.98, 148.46, 147, 50,, 138.14, 137.04, 133.12, 132.91, 129.36, 128.84, 128. 21,127. 32,125. 13,124. 82, 124.49, (four aromatic resonances obscured or coincident), 96. 81 (backbone-CH), 21. 46, 21.21, 20.95, 20.70, 20.45. 20.19 (one backbone Me obscured or coincident); Anal. Calcd for C55H6oN4Cu2 : C, 73.06 ; H, 6.69 ; N, 6.20. Found: C, 73.19 ; H, 6.65 ; N, 6.09.

At -70 °C, [Me2NN]Cu=CPh2 (4) and [Me2NN] Cu (toluene) (5) were also present in ca. 2% of the concentration {[Me2NN]Cu}2(µ-CPh2) (3) as determined by'H NMR.

Selected'H NMR resonances for [Me2NN] Cu=CPh2 (4): 8 7.400 (d, 2, o-Ph), 4.958 (s, 1, backbone-CIl), 2.026 (s, 6, Ar-CH3) ; Selected'H NMR resonances for [Me2NN] Cu (toluene) (5): 8 4.801 (s, 1, backbone-CH), 2.384 (s, 6, Ar-CH3). With increasing temperature, 4 and 5 increased in intensity at the expense of 3.

The thermal decomposition of compound 2 in benzene-d6 (ca. 20 mM) was monitoredbylHNMR spectroscopy. After 56 h at room temperature, 57 % of the initial concentration of 2 was still present. The other p-diketiminate containing product observed was the solvento species [Me2NN] Cu (benzene-d6).

Example 4 Preparation of [Me2NN] Cu (toluene) (5). A solution of [Me2NN] Tl (0. 450 g, 0. 883 mmol) in 5 mL toluene was stirred with powdered CuBr (0. 325 g, 2. 262mmol) for one day.

The volatiles were removed in vacuo, the residue was extracted with 10 mL of pentane, and the mixture was filtered through Celite. The filtrate was concentrated, a few drops of toluene were added, and the solution was allowed to stand at -35 °C to give 0. 118 g (28. 9 %) dark brown crystals. 1H NMR (benzene-d6): # 6. 9-7.1 (m, 11, Ar-Il), 4.769 (s, 1, backbone-CH), 2.128 (s, 3, toluene-CH3), 2.011 (s, 12, Ar-CH3), 1.625 (s, 6, backbone- CH3) ; l3C {lH} NMR (benzene-cl6, partial data): 162.42, 150.55, 132.33, 130.63, 129.28, 94.42 (backbone-CH), 23.28, 19.03, 18.69 ; Anal. Calcd for C28H33N2Cu : C, 72.93 ; H, 7.21 ; N, 6.07. Found: C, 72.66 ; H, 7.09 ; N, 5.94.

Example 5 Determination of thermodynamic parameters AH and AS for the dissociation of one [Me2NN] Cu fragment from {[Me2NN] Cu} 2 (ll-CPh2) (3) in toluene. A sample of {[Me2NN]Cu}2(µ-CPh2) (0. 020 g, 0. 024 mmol) was dissolved in 1 mL of toluene-d8 in a volumetric flask and transferred in to NMR tube.'H NMR spectra were acquired every 10

degrees over the range of temperatures-20 to 60 °C. The use of relative integrals for the p- diketiminato backbone C-H resonances corresponding to {[Me2NN]Cu}2(µ-CPh2) (3) (6 5.010 ppm), [Me2NN] Cu=CPh2 (4) (6 4.958 ppm) and [Me2NN] Cu (toluene) (5) (ä 4.801 ppm) against an internal standard allowed the calculation of the equilibrium constants at different temperatures using the following dependence with an initial {[Me2NN] Cu} 2 (ll- CPh2)} (3) concentration of 0.023 M: Kcq = [initial concentration (M) of 3] # {([Me2NN]Cu=CPh2) # ([Me2NN]Cu(toluene) } {[Me2NN]Cu}2(µ-CPh2)} A van't Hoff plot of In Keq vs. 1/T allowed in calculation of AH = 9.1 (3) kcal/mol (from slope) and AS = 24 (1) cal/mol K (from intercept).

Example 6 Reaction of {[Me2NN]Cu}2(µ-CPh2) (3) with styrene. Styrene (0.010 g, 0.009 mmol) and {[Me2NN]Cu}2(µ-CPh2) (0.026 g, 0.003 mmol) were dissolved in 0.75 mL benzene-d6 and stirred until the purple color of 2 completely disappeared (ca. 45 minutes). 1H NMR analysis showedthat [Me2NN] Cu (styrene) at 8 4. 858 ppm (1H, s, backbone C-H) 2.215 ppm (6H, b r. s, A r-CH3), 1.724 ppm (6H, b r. s, Ar-CH3), 1. 585 ppm (6H, s, backbone- CH3), and 1,1, 2-triphenylcyclopropane at 8 2.870 ppm (1H, m, CHPh) were formed in a 2: 1 ratio. 1,1, 2-triphenylcyclopropane was also identified by GC-MS.

Example 7 Reaction of {[Me2NN]Cu}2(µ-CPh2) (3) with N2CPh2. A solution of N2CPh2 (0.028 g, 0.128 mmol) in 2 mL of toluene was added with stirring to a solution of {[Me2NN] Cu} 2 (1l- CPh2) (0.114 g, 0.126 mmol) in 5 mL ether. After stirring at room temperature for 15 minutes, the reaction mixture was placed into the freezer and allowed to stand overnight.

Colorless crystals were isolated by decantation of the solution, rinsed with chilled pentane, and dried in vacuo to give 0. 019 g (37%) of the azine Ph2C=N-N=CPh2 whose identity was confirmed by GC-MS.

Example 8 Survey of reactivity of {[Me2NN]Cu}2(µ-CPh2) (3) with different olefins. A 10.0 mL solution of { [Me2NN] Cu} 2 (-CPh2) (0.101 g, 0.112 mmol, 0.012 mM) in toluene was divided into five 2.0 mL portions. 50 equivalents of each olefin (1.117 mmol) were added individually to separate 2.0 mL portions of dicopper carbene. In the case of styrene and a- methylstyrene, the corresponding solutions turned yellow within 2 h at room temperature.

For the other alkenes, the resulting solutions were heated at 45 °C for 2 h to completely discharge the intense purple color of the copper carbene species. A solution of naphthalene (0.052 g) in 10.0 mL toluene was divided to five 2 mL portions and added individually as an internal standard to each of the five solutions above. The resulting solutions were analyzed by GC-MS (Table 4). In all cases the yield of Ph2C=CPli2 was determined directly against the internal naphthalene standard. The yield of cyclopropane was obtained by mass balance since no other Ph2C-containing products were observed. In the case of styrene, the quantitative conversion to 1,1, 2-triphenylcyclopropane was verified using against an authentic standard. A blank solution without olefin was decomposed under the same conditions to give a quantitative yield of Ph2C=CPh2.

Table 4. Cyclopropanation of alkenes by {[Me2NN]Cu}2(µ-CPh2) (3). olefin yield of cyclopropane tetraphenylethylene (%) reaction time % lu styrene 100 0 1/2 a-methylstyrene 100 0 2 trans-p-26. 8 (32. 0a) 73.2 2 (45 oC) b methylstyrene cycloocetene 19. 7 80. 3 2 (45 °C) 1-hexene 21. 0 79. 0 2 (45 oC) b No olefin 0 100 2 (45 °C) a This yield was determined directly from the cyclopropane peak area using the same response factor determined for 1,1, 2-triphenylcyclopropane. bNo change after stirring for 2 h at RT, then heated to 45 °C for 2h.

Example 9 Preparation of [Me3NN] Cu (toluene). An analogous procedure as for [Me2NN] Cu (toluene). was followed employing [Me3NN] Tl (0.491 g, 0.913 mmol) and CuBr (0. 386 g, 2.690 mmol) to give 0.148 g (33.2 %) dark brown crystals. 1H NMR (benzene-d6) : 8 6.8-7. 1 (m, 11, Ar-H), 4.797 (s, 1, backbone-CH), 2.269 (s, 6, Ar-CH3), 2.106 (s, 3, toluene-CH3), 2.032 (s, 12, Ar-CH3), 1.672 (s, 6, backbone-CH3) ; 13C {lH} NMR (benzene-d6, partial data): 162.72, 160.96, 148.19, 141.80, 137. 80, 131.97, 130.30, 129.26, 94.46 (backbone-CH), 23.27, 21.15, 18. 98,18. 65; Anal. Calcd for C3oH37N2Cu : C, 73.66 ; H, 7.62 ; N, 5.73. Found: C, 73.34 ; H, 7.31 ; N, 5.31.

Example 10 Preparation of [Me3NN] Cu=CPh2 (8). A cooled (-35 °C) solution of N2CPh2 (0.061 g, 0. 280 m mol) i n 3 m L o f e ther w as a dded w ith stirring t o a cooled (-35 °C) s olution o f [Me3NN] Cu (toluene) (0.135 g, 0.276 mmol) in 5 mL ether. The color of solution turned metallic purple immediately. After stirring at room temperature for 3 min, the reaction mixture was filtered through Celite, and the filtrate was concentrated and allowed to stand at-35 °C to give dark purple crystals. The product was isolated and recrystallized from pentane at-35 °C to afford 0.031 g (20 %) of product. lH NM1R (benzene-d6) : 6 7.376 (dd, 4, nz-CPh), 7. 138 (m, 2, p-CPh), 6. 866 (t, 4, o-CPh), 6.643 (s, 4, Ar-H), 4.941 (s, 1, backbone-CH), 2.331 (s, 12, Ar-o-CH3), 1.996 (s, 6, Ar-p-CH3), 1.593 (s, 6, backbone- CH3) ; 13C {lH} NMR (benzene-d6) : 8 253.10 (CPh2), 162.23, 155.86, 148.83, 132.54, 130.89, 129.23, 128. 92, 128. 88, 128. 82, 96.44 (backbone-CH), 23.18 (Ar-o-CH3), 21.27 (Ar-p-CH3), 19.31 (backbone-CH3) ; Anal. Calcd for C36H39N2Cu : C, 76.77 ; H, 6.98 ; N, 4.97. Found: C, 76.89 ; H, 6.73 ; N, 4.63.

Example 11 Kinetic studies for the cyclopropanation of styrene with [Me3NN] Cu=CPh2 (8) in 1,4- dioxane. A 25.0 mL stock solution of [Me3NN] Cu=CPh2 (11.8 mg, 0.021 mmol) and styrene (218 mg, 2.10 mmol) in 1,4-dioxane was prepared using a volumetric flask. This stock solution was divided to five 5.0 mL portions and each was frozen in dry ice until used. In separate experiments, he decreasing concentration of [Me3NN] Cu=CPh2 over time was quantified by W-vis spectroscopy by monitoring the decrease in intensity of the band due to 8 at = 566 nm at the temperatures 17.5, 30.2, 40.5, 50.0, and 60. 2 °C. Data were generally taken for ca. 3 half-lives. Temperatures can be deemed accurate i 0. 5 °C. Plots of

ln [ArA] versus time gave straight lines with observed rate constants that appear in Table 2. Uncertainties in reported rate constants were estimated on the basis of inspection of the sensitivity of the fits of the In [At-Aoo] versus time plots. The concentration of styrene was 0.08385 M in each case, leading to Icact = kobs/0. 0839 M.

Example 12 Relative rates for cyclopropanation of para-substituted styrenes (p-X-C6H4-CH=CH2) with [Me3NN] Cu=CPh2 (8). Two separate methods were used to determine the relative rates of cyclopropanation kx/kH for para-substituted styrenes (X = OMe, M, H, CF3) compared to styrene (X = H) collected in Table 5 used to prepare the Hammet plot.

(a) Competition experiments. A solution of [Me3NN] Cu=CPh2 (10.9 mg, 0.019 mmol) with an internal standard of naphthalene in 1,4-dioxane was diluted to 1 0. 0 mL using a volumetric flask. The solution was divided to five 2 mL portions to which styrene and a substituted styrene was added. The solutions were stirred for lh and analyzed by GC-MS.

The yield of 1,1, 2-triphenylcyclopropane (YH) was determined against the naphthalene standard. As < 1 % Ph2C=CPh2 was observed in each of these competition experiments, the yield of the p-substituted 1,1, 2-triphenylcyclopropane (Yx) was determined by mass balance. The relative rate kx/kH is thus determined by the relationship : kx/kH= = YX/YH = (100-YH)/YH.

(b) Direct kinetic measurements. For comparison, kinetic studies were carried out with para-substituted styrenes (X = OMe, Me, H, CF3) by the method described for the cyclopropanation of styrene by 8 using 100 equivalents of the substituted styrene. The temperature of the UV-vis cell was thermostated at 40. 0 °C during the kinetic measurements for each member of the series. The rate constants kx and kH thus were independently measured under identical conditions allowing for the tabulation of kx/kH for each styrene derivative.

Table 5. Relative rates of cyclopropanation of styrene derivatives by [Me3NN] Cu=CPh2 (8).

Styrene derivative Rate constant for Cyclopropane kx/k} kx/kn (p-X-C6H4-CH=CH2) cyclopropanation yield (X=H) (competition) (UV-vis) (UV-vis, kobs (s-1) ) (% X = OMe 7.27 (9) x 10-4 30. 3a 2. 3a 2.95 X = Me 3.65 (5) x 10-4 41.5 1.41 1.48 X = H 2. 47 (5) x 10-4 100 1. 00 1. 00 X = CF3 1.35 (5) # 10-4 49. 5 1.02 1.28 (1. 05 (5) x 1 o-4) b a The yield of 1,1, 2-triphenylcyclopropane could not be accurately obtained due to the overlapping of p- methoxystyrene and the naphthalene standard in the gas chromatogram. The ratio of kX/kH comes from the ration of peak area in GC-MS. b The relative rate for cyclopropanation of para-trifluoromethylstyrene vs. styrene was determined in a separate run; the number in parenthesis is the corresponding rate constant for styrene cyclopropanation under the slightly different conditions.

Example 13 Kinetic studies for decomposition of [Me3NN] Cu=CPh2 (8) in 1, 4-dioxane at various temperatures. A 25.0 mL stock solution of [Me3NN] Cu=CPh2 (11.8 mg, 0.021 mmol) in 1, 4-dioxane was prepared using a volumetric flask. This stock solution was divided to five 5.0 mL portions and frozen in dry ice until used. In separate experiments, he decreasing concentration of [Me3NN] Cu=CPh2 over time was quantified by UV-vis spectroscopy by monitoring the decrease in intensity of the band due to 8 at 4lax = 566 nm at the temperatures 32.2, 40.0, 49.0, and 60. 0 °C. Data were generally taken for ca. 3 half-lives.

Temperatures can be deemed accurate 0. 5 °C. Plots of In [At-Aoo] versus time gave straight lines with observed rate constants that appear in Table 3. Uncertainties in reported rate constants were estimated on the basis of inspection of the sensitivity of the fits of the In [At-A] versus time plots.

Example 14 Thermal decomposition of [Me3NN] Cu=CPh2 (8) in benzene-d6. An approximate 40 mM s olution o f [Me3NN] Cu=CPh2 (0.015 g) i n b enzene-d6 (0.7 m L) was prepared and monitored by 1H and 13C {lH} NMR spectroscopy at room temperature. Within 2.5 h, the 13C NMR signal of CPh2 at 8 253.10 ppm decayed and a new resonance at 8 189.0 ppm grew in. After 12h, there was a 1.55 : 1.00 : 0.19 molar ratio of {[Me3NN]Cu}2(µ-CPh2) /

[Me3NN] Cu=CPh2/ [Me3NN] Cu (benzene-d6) in the solution. Partial NMR data for { [Me3NN] Cu} 2 (-CPh2) (9) : lH NMR (benzene-d6) : b 5. 018 (s, backbone-CH), 1.624 (s, backbone-CH3), 1.8-2. 3 (br., Ar-CH3) ; 13C {lH} NMR (benzene-d6,) : b 189.0 (CPh2), 97.11 (backbone-CH), 23.92 (Ar-o-CH3), 21. 28 (Ar-p-CH3), 19.99 (backbone-CH3) ; Partial data for [Me3NN] Cu (benzene-d6) : 1H NMR (benzene-d6) : b 4. 810 (s, backbone-CH), 2.033 (s, 12, Ar-CH3).

Example 15 X-ray Structure Refinement Details. Single crystals of each compound were mounted under mineral oil on glass fibers and immediately placed in a cold nitrogen stream at-90 (2) °C on a Bruker SMART CCD system. Hemispheres of data were collected (0. 3°-scans ; 20maX = 56° ; monochromatic Mo Ka radiation, k = 0.7107 A) and integrated with the Bruker SAINT program. Structure solutions were performed using the SHELXTL/PC suite and XSEED. Intensities were corrected for Lorentz and polarization effects and an empirical absorption correction was applied using Blessing's method as incorporated into the program SADABS. Non-hydrogen atoms were refined with aniostropic thermal parameters and hydrogen atoms were included in idealized positions. Because disordered hexane molecules of solvation were found in the initial refinement of {[Me2NN] Cu} 2 (p- CPh2) (3) that could not be satisfactorily modeled, the SQUEEZE subroutine of PLATON was u sed. 3 14 s olvent electrons w ere i dentified c orresponding t o ca. 0.75 m olecules o f hexane per {[Me2NN] Cu} 2 (F-CPh2) (6 hexanes per unit cell) and the reflection data were refined excluding the solvent to give the refinement details.

Exafflple 16 Calibration procedure for quantitative GC/MS analysis. A mixture of styrene (0.253 g, 2.43 mmol), {[Me2NN]Cu}2(µ-CPh2) (0.110 g, 0.122 mmol) and 5 mL of toluene was stirred until the solution turned to light yellow, and then naphthalene (0. 028 g) was added as standard. Since analysis by GC/MS showed that the only other CPli2-containing species Ph2C=CPh2 was present in an extremely low amount (<1%), the carbene group (CPh2) was essentially quantitatively (> 99%) transferred to styrene to form a cyclopropane; thus we assume that the mass of the yet formed cyclopropanation is the theoretical yield based on

the starting material of { [Me2NN] Cu} 2 (t-CPh2) that allows the following equation to be developed: M(mass of cyclopropanation S(peak area of cyclopropanation) = * R(factor)<BR> <BR> M(mass of naphthalene) S(peak area of naphthalene) Then this R (factor) can be applied to other cyclopropanation yield calculations by adding a certain amount of naphthalene as a internal standard.

Example 17 Cyclopropanation of a mixture of styrene and p-methoxystyrene with 3. A mixture of {[Me2NN] Cu} 2 (ll-CPh2) (0.060 g, 0.066 mmol), styrene (0.070 g, 0.67 mmol), and 4- methoxyl-styrene (0.089 g, 0.66 mmol) was stirred in 5 mL of toluene until the solution turned t o 1 ight yellow (ca. 4 0 m inutes). A nalysis o f an a liquot b y G C-MS s howed t hat 1,1, 2-triphenylcyclopropane and 1, 1-diphenyl-2- (p-methoxy) phenylcyclopropane were formed in a ratio of 40: 60 indicating that cyclopropanation of the more electron-rich p- methoxystyrene is somewhat favored over styrene.

Exampel 18 3,5-dimethylnitrosobenzene (O=NAr). Prepared by an analogous procedure used for 2,4- dimethylnitrosobenzene (See Mel'nikov, E. B.; Suboch, G. A.; Belyaev, E. Y. Russ. J. of Org. Chem. 1995,31, 1640): To a solution of 3, 5-dimethylaniline (5.05 g, 41.7 mmol) in a 1: 1 pentane and dichloromethane mixture (200 mL) was added Na2W04-2H20 (0.66 g, 2.0 mmol), tetrabutylammonium bromide (0.2 g, 0.6 mmol), and 30 % aqueous hydrogen peroxide (20 mL). The mixture was vigorously stirred for 18 hr at RT. The organic layer was separated and washed with 0.01 M HCl (100 mL) followed by water (100 mL). The organic layer was then dried over anhydrous MgS04. The organic layer was concentrated to dryness and the resulting yellow solid was recrystallized using pentane and dichloromethane (1: 1) to afford 2.03 g (36%) of the product as yellow crystals.'H NMR (C6D6): 8 7.356 (s, 2, Ar-R), 6.754 (s, 1, Ar-X), 1.954 (s, 6, Ar-CH3) ; 13C {'H} NMR (C6D6) : 8 166.75, 138. 98,136. 51, 118. 84,20. 65 (Ar-CH3) ; VN=o (cm-1) : 1613; Anal. Calcd for C8HgNO : C, 71.09 ; H, 6.70 ; N, 10.36. Found: C, 71.08 ; H, 6.56 ; N, 10.00.

Example 19 Col2 (2,4-lutidine) 2. Prepared by a similar procedure used for CoX2 (2,4-lutidine) 2 (X = Cl, Br) (See Kansikas, J.; Leskelä, M.; Kenessey, G.; Wadstern, T.; Liptay, G. Acta. Claern.

Scand. 1996,50, 267): A solution of CoI2 (1.57 g, 5.02 mmol) in 10 mL acetonitrile was added with stirring to a solution of 2, 4-lutidine (1.62 g, 15.0 mmol) in 5 mL acetonitrile.

The mixture immediately turned from blue to deep green and teal crystals began to form.

After stirring for 10 minutes, the solution was cooled to-35°C. The teal crystals which had formed were collected on a frit, washed with ether and dried in vacuo to afford 2.32 g (87. 5%) of product. Anal. Calcd for Cl4Hl8N2I2Co2 : C, 31.90 ; H, 3.44 ; N, 5.32. Found: C, 32. 08 ; H, 3.36 ; N, 5.26.

Example 20 [Me2NN] CoI (2, 4-lutidine) (9). A solution ofTl [Me2NN] (1.46 g, 2. 86 mmol) in 10 mL THF was added with stirring to a suspension of CoI2 (2,4-lutidine) 2 (1.51 g, 2.87 mmol) in 20 mL THF. The solution immediately turned green. After stirring overnight, the solution was filtered through C elite, the filtrate w as c oncentrated and diluted with ether, and the resulting solution was cooled to-35°C to afford 1.49 g (86.9%) of red crystals.

Recrystallization from THF afforded crystals suitable for X-ray diffraction. Ileff= 3.60 B. M.

(C6D6) ; Anal. Calcd for C2gH34N3ICo : C, 56.22 ; H, 5.73 ; N, 7.02. Found: C, 56.79 ; H, 5. 82 ; N, 6.98.

Exacsnple 21 [Me2NN] Co (n''-toluene) (10). Dry magnesium powder (2.0 g, 82 mmol) was added to a solution of [Me2NN] CoI (2,4-lutidine) (3.30 g, 5.51 mmol) in 40 mL toluene. After stirring for 24h, the volatiles were removed in vacuo and the residue was extracted with ether (40 mL). Magnesium salts were precipitated by the addition of dioxane (1.5 mL, 18 mmol) with stirring, the mixture was filtered through Celite, and the filtrate was concentrated and cooled to-35°C. The red crystals which had formed were collected on a frit, washed with cold pentane and dried in vacuo to afford 1.56 g (62. 1 %) of product. Recrystallization from ether afforded red crystals suitable for X-ray d iffraction. R, ff = 2.69 B. M. (C6D6) ; Anal.

Calcd for C2sH33N2Co : C, 73.67 ; H, 7.29 ; N, 6.14. Found: C, 72.29 ; H, 6.99 ; N, 6. 31.

(Consistent low carbon analysis due extreme 02 sensitivity. )

Example 22 {[Me2NN] Co} 2 () -0) 2 (11). With a syringe, dry O2 gas (12 mL @ RT and 1 atm, 0.54 mmol) was slowly bubbled into a solution of [Me2NN] Co (P6-toluene) (0.169 g, 0.370 mmol) in 15 mL diethyl ether at room temperature. The solution turned purple immediately.

The solution was filtered through Celite, and the filtrate was concentrated and cooled to- 35°C. The maroon crystals which had formed were separated from the solvent, washed with cold pentane and dried in vacuo to afford 0.102 g (74.5%) of product. Recrystalization from ether afforded red crystals suitable for X-ray diffraction.'H NMR (C6D6) : 8 6.420 (d, 4, Ar-H), 6.149 (t, 2, Ar-H), 3.263 (s, 6, backbone-CH3),-0. 345 (s, l, backbone-CH), - 2.341 (s, 12, Ar-CH3) ; 13C{1H} NMR (C6D6) : 8 265.74 (backbone-C-Me), 170.48 (backbone-CH), 131.62 (Ar-m-CH), 122.99 (Ar-p-CH), 119.78 (Ar-ipso-C), 116.00 (Ar-o- C), 42.81 (backbone-CH3), 10.92 (Ar-CH3) ; eff = 3.96 B. M. (C7D8 ; RT) ; Anal. Calcd for C42H5oN402Co2 : C, 66.31 ; H, 6.62 ; N, 7.36. Found: C, 66.65, H, 6.79, N, 7.23.

Example 23 {[Me2NN]Co} 2 () J-NAr) 2 (12). A solution of 3, 5-dimethylphenylazide (0.051 g, 0.34 mmol) in e ther (5 m L) w as s lowly a dded w ith s tirring to a s olution o f [Me2NN] Co (ll6-toluene) (0.158 g, 0.346 mmol) in ether (10 mL). Effervescence (N2) was immediately observed.

After stirring for 30 min, the solution was filtered through Celite, and the filtrate was concentrated and cooled to-35°C to afford 0.092 g (56%) of red crystals. Recrystallization from ether afforded red crystals suitable for X-ray diffraction. J, eff = 8. 80 B. M. (C6D6) ; Anal. Calcd for Cs8H68N6Co2 : C, 72.03 ; H, 7.09 ; N, 8.69. Found: C, 72.17 ; H, 6.97, N, 8.57.

Example 24 [Me2NN] CoNAd (13). A solution of 1-adamantylazide (0.096 g, 0.54 mmol) in ether (5 mL) was slowly added with stirring to a solution of [Me2NN] Co (rl6-toluene) (0.246 g, 0.539 mmol) in ether (10 mL). After stirring for 30 min, the solution was filtered through Celite, and the filtrate was concentrated and cooled to-35°C. The red crystals which had formed were separated from the solvent, washed with cold ether and dried in vacuo to afford 0. 138 g (49.7%) of product. l Recrystalization from ether afforded red crystals suitable for X-ray diffraction. 1H NMR (C6D6) : 8 7.55 (d, 4, Ar-X), 7.35 (t, 2, Ar-H), 4.188 (s, 1, backbone-CH), 3.173 (s, 12, Ar-CH3), 1.735 (s, 6, backbone-CH3), 1.11 (m, 3, Adamantyl-CH), 0.973 (br. , 6, Adamantyl-CH2), 0.443 (s, 6, Adamantyl-CH2) ; l3C {lH} NMR (C6D6) : 8 161.50, 157.63, 133.46, 128.78, 125.77, 90.601 (backbone-CH), 51.02 (N-

C), 36.14, 27.22, 27.01, 21.47, 20.66. Anal. Calcd for C31H4oN3Co : C, 72.49 ; H, 7.85 ; N, 8.18. Found: C, 72. 31 ; H, 7.64, N, 7. 85.

ExaxnPle 25 {[Me2NN]Co}2(µ-O)(µ-NAr) (14). A solution of 3,5-dimethylnitrosobenzene (0.030 g, 0.22 mmol) in ether (5 mL) was slowly added with stirring to a solution of [Me2NN] Co (il 6_ toluene) (0.200 g, 0. 438 mmol) in ether (15 mL). After stirring for 2h, the solution was filtered through Celite, and the filtrate was concentrated and cooled to-35°C. The red crystals which had formed were separated from the solution, washed with cold pentane, and dried in vacuo to afford 0.065g (33%) of product. Recrystalization from ether afforded red crystals suitable for X-ray diffraction. p. eff = 4.93 B. M. (C6D6) ; Anal. Calcd for CsoH59Ns0Co2 : C, 69. 51 ; H, 6.89 ; N, 8.11. Found: C, 69.27 ; H, 7.20 ; N, 8. 31.

Exasxple 26 Computational Experiments: The prelimimary D calculations employed the Becke- Perdew exchange correlation functional using the Amsterdam Density Functional suite of programs (ADF 2002.03). See (a) Becke, A. Phys. Rev. A 1988, 38, 3098 ; (b) Perdew, J. P.

Phys. Rev. B 1986, 34, 7406; (c) Perdew, J. P. Plzys. Rev. B 1986, 33, 8822 ; (d) te Velde, G. ; Bickelhaupt, F. M.; Baerends, E. J. ; Fonseca Guerra, C.; Van Gisbergen, S. J. A.; Snijders, J. G. ; Ziegler, T. J. Comput. Claem. 2001,22, 931 and references therein; (e) Fonseca Guerra, C.; Snijders, J. G.; te Velde, G. ; Baerends, E. J.; Acc., T. C. Tlaeor. Cheafa.

24cc. 1998, 99, 391; and (f) ADF2002.03, SCM, Theoretical Chemistry, Vrije Universieit, <BR> <BR> <BR> Amsterdam, The Netherlands, http : //www. scm. com. Slater-type orbital (STO) basis sets employed for H, C, and N atoms were of triple- quality augmented with two polarization functions (TZP2/ADF basis V) while an improved triple- basis set with two polarization functions (TZP2+) was employed for the Co atom. The ls electrons of C and N as well as the 1 s-2 p e lectrons o f C o w ere treated as frozen c ore. T he V WN (Vosko, W ilk, a nd Nusair) functional was used for LDA (local density approximation). See Vosko, S. H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58, 1200.

Employing typical bond distances and angles for the p-diketiminate ligand and the imido t-butyl substituent as well as Co-N and N-Co-N angles similar to those determined in the X-ray structure of [Me2NN] Co-NAd (13), coordinates for a model of [Me2NN] Co NBut possessing Cs symmetry (z->-z) were developed in the coordinate system shown in Scheme 9. These coordinates were optimized and converged to give a

structure (Figure 3) whose Co-N distances and N-Co-N angles are in excellent agreement with the experimentally determined structure of [Me2NN] Co=NAd (Table 6). In this preliminary calculation to identify the electronic structure of a C2v-like [Me2NN] Co=NR species possessing a linear CoN-R linkage (consistent with the observed solution structure of 13 at-80 °C), bending of the imido substituent as well as the slight displacement of the Co atom from the N3-plane observed in the X-ray structure of 13 were not considered.

Table 6. Selected calculated vs. experimentally determined distances (A) and angles (°). Parameter Calculated Experiment Col-N3 1. 622 1.624 (4) Col-Nl 1.856 1. 854 (4) Col-N2 1.856 1.855 (4) N1-Col-N2 92.5 92.76 (17) Nl-Co-N3 133.7 131.9 (2) N2-Co-N3 133. 7 132.3 (2) Scheme 9. Schematic representation of metal-imide multiple bonding for linear imides [Me2NN] Co NR based on DFT calculations (same coordinate system as in calculations). ruz -N zon RN--)--M7c-donation dyz N d Coi du2 "Col T dxz dX2_ya RN-. RN-MTC-donation -N N (dxy) \))

Exccmmde 27 X-ray structure refinement details : S ingle crystals of each compound were mounted under mineral oil on glass fibers and immediately placed in a cold nitrogen stream at-90 (2) °C on a Bruker SMART CCD system. Full spheres of data were collected were collected (0. 3° #-scans ; 2#max = 56° ; monochromatic Mo Ka radiation, X = 0.7107 A) and integrated with the Bruker SAINT program. Structure solutions were performed using the SHELXTL/PC suite and XSEED. See SHELXTL-PC, Vers. 5.10 ; 1998, Bruker-Analytical X-ray Services, Madison, WI; G. M. Sheldrick, SHELX-97, Universität Göttingen, Göttingen, Germany and L. Barbour, XSEED, 1999. Intensities were corrected for Lorentz and polarization effects and an empirical absorption correction was applied using Blessing's method as incorporated into the program SADABS. See SADABS; G. M.

Sheldrick, 1996, based on the method described in R. H. Blessing, Acta Crystallogr., Sect.

A, 1995,51, 33. Non-hydrogen atoms were refined with aniostropic thermal parameters and hydrogen atoms were included in idealized positions.

Specific details for {[Me2NN]Co}2(µ-O)2 (11) : After all non-H atoms of 11 were anisotropically refined (including oxygen atom 01 in a square planar site) and H atoms were p laced in idealized p ositions, F ourier p eaks ofl. 31andl. l7e'/A w ere p resent a t 1. 883 and 1. 838 A, respectively, from both Col and Col'. These peaks were symmetrically disposed about Col and Col'in a tetrahedral manner and were modeled as disordered, non-symmetry related oxygen atoms that give rise to partial occupancy of tetrahedrally coordinated Co centers for which the Col and all p-diketiminate atom positions are not altered. Taking into account that 01 generates the symmetry related O1' that completes square-planar coordination at Col and Col', these peaks assigned as 02 and 03 were allowed to isotropically refine against 01 after constraining their isotropic thermal parameters to be identical to that of O1. This gave an occupancy ratio of 86: 14 (01 : (02,03)). Fixing the occupancy ratio, releasing the thermal parameter constraint, and anisotropically refining O1 while isotropically refining 02 and 03 led to a reduction of Rl [I > 2a (I) ] from 6.05% to 5.36% with a concomitant reduction in the maximum peak height from 1.308 e~/Å3 to 0.601 e/Å3. This final maximum Fourier peak was located in a non- chemically relevant position nearly coincident to the Col-Col'vector 1.79 A from Col and 1.00 A from Col'.

Exam ple 28 Preparation of {[Me2NN]Co}2(µ-CPh2) To a solution of [Me2NN] Co (toluene) (0.203 g, 0.445 mmol) in 10 mL toluene, a solution of N2CPh2 (0.048 g, 0.220 mmol) in 8 mL of toluene was added by a syringe pump at room temperature over a period of 8 h while stirring and the resulting solution was stirred overnight. The volatiles were removed in vacuo and the residue was extracted with ether (10 mL) and filtered through Celite. The filtrate was concentrated and allowed to stand at-35 °C. Dark brown crystals which had formed were collected on a frit, washed with cold ether, and dried in vacuo to afford 0.122 g of {[Me2NN] Co} 2 (1l-CPh2) 0. 5 diethyl ether (59 %) of product as a 2: 1 ether solvate.

Recrystallization from pentane afforded crystals of {[Me2NN] Co} 2 (p-CPh2) 0. 5 pentane suitable for X-ray diffraction. (see 03080t. cif for X-ray data) lH NMR (benzene-d6, RT, <BR> <BR> <BR> partial data): 8 35.88, 27.33, 16.20, 12. 08,-1. 79, -4.42,-8. 68,-10. 70, -14.63,-33. 55, - 42.45,-50. 28, -62.47 ppm.

Example 29 Reaction of {[Me2NN] Co} 2 (p-CPh2) with styrene. Styrene (0.105 g, 1.008 mmol) and {[Me2NN]Co}2(µ-CPh2) (0.046 g, 0.050 mmol) was dissolved in 5 mL of toluene and stirred overnight, and the resulting solution was passed through silica gel and analyzed by GC-MS to give ca. 95 % yield of 1,1, 2-triphenylcyclopropane along with another unidentified constitutional isomer of the same mass as 1, 1, 2-triphenylcyclopropane in ca.

5% yield.

Example 30 Catalytic cyclopropanation of styrene by 9. To a solution of [Me2NN] Co (toluene) (0.014g, 0.031 mmol) and styrene (0.625 g, 6.01 mmol) in 10 mL toluene, a solution of N2CPh2 (0.132 g, 0.606 mmol) in 8 mL of toluene was added by syringe pump at room temperature over a period of 14 h. After stirring at RT for another 6 h, the resulting solution was passed through silica gel and analyzed by GC-MS to give a mixture of Ph2CH2, 1,1, 2-triphenylcyclopropane along, tetraphenylethylene and Ph2C=N-N=CPh2 with an approximate ratio of 1: 2: 2: 5.

Incorporation by Reference All of the patents and publications cited herein are hereby incorporated by reference.

Equivalents Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.