dppf-Like Compounds and Methods

Statement of Governmental Rights

This invention was made with government support under CHE1240020 awarded by National Science Foundation. The government has certain rights in the invention.

Field of the Invention

Disclosed is a method of β-hydride elimination and subsequent 2,1 - insertion from a transient nickel(ll) acrylate hydride intermediate (Structure I).

Structure I

Also addressed is treatment of (dppe)Ni(CH(CH ₃ )C0 ₂ BAr ^f ₃ ) with a nitrogen containing base to produce a diphosphine nickel(O) r| ² -acryl borate adduct such

where Fc is ferrocene;

where Ph is a phenyl group

where P is phosphorus;

where Ar ^f is a fluorinated aryl substituent;

where B in BAr ^f ₃ is a boron linked to three fluorinated aryl substituents;

where aryl refers to a functional group or substituent derived from an aromatic ring; and, where superscript f references a haloginated aryl, phenyl, naphthyl, thienyl, or indolyl with at least one halogen; and,

where R ¹ is, for example, C-i-C-i ₂ -alkyl such as methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 1 -(2-methyl)propyl, 2-(2-methyl)propyl, 1 -pentyl, 1 -(2- methyl)pentyl, 1 -hexyl, 1 -(2-ethyl)hexyl, 1 -heptyl, 1 -(2-propyl)heptyl, 1 -octyl, 1 - nonyl, 1 -decyl, 1 -undecyl, 1 -dodecyl, C ₃ -Ci ₀ -cycloalkyl which is unsubstituted or may bear a CrC ₄ -alkyl group, for example cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl and norbornyl, aryl which is unsubstituted or may bear one or two substituents selected from chlorine, Ci-C ₈ - alkyl and CrC ₈ -alkoxy, such as phenyl, napthyl, tolyl, xylyl, chlorophenyl or anisyl.

Background of the Invention

The utilization of CO ₂ as a feedstock for the production of commodity chemicals potentially offers a more cost effective and renewable alternative to fossil fuel based carbon sources in the chemical industry. Unfortunately, the kinetic and thermodynamic stability of CO ₂ has limited its exploitation thus far to a handful of commercial chemicals. One method to surmount this stability is the reduction of CO ₂ via coupling to other relatively high energy small molecules. The functionalization of CO ₂ with light olefins to produce α,β-unsaturated carboxylic acids is yet another intriguing target for this methodology, with potentially significant implications for the manufacture of acrylates used in superabsorbent polymers, elastomers, and detergents.

Transition metal promoted coupling of CO ₂ and ethylene toward acrylate formation has been explored as an alternative to currently used propylene oxidation technology since the seminal reports of Hoberg and Carmona in the 1980's (Illustration 1 ). These pioneering investigators independently pursued new routes for CO ₂ -ethylene coupling using zerovalent nickel and group VI metals, respectively, though catalytic activity remained elusive. Illustration-! . Reported C0 ₂ -ethylene coupling at transitions metal complexes.

Hoberg

Carmona

Limbach and co-workers have reported circumventing barriers to β- hydride elimination by adding external bases such as sodium terf-butoxide to diphosphine nickalalactone species which are believed to deprotonate the β- hydrogen directly without necessitating transfer of the hydride to nickel. This approach affords sodium acrylate (NaC0 ₂ CHCH ₂ ) in good yield and by repeated sequential additions of C0 ₂ , ethylene and base several equivalents of sodium acrylate may be obtained in one reaction vessel. Unfortunately, the strong sodium base required for the deprotonation is not compatible with the high C0 ₂ pressure needed for nickelalactone formation, obviating catalytic production under a constant set of reaction conditions.

Summary of the invention

The Lewis acid tris(pentafluorophenyl)borane rapidly promotes ring opening β-hydride elimination in a 1 , 1 '-bis(diphenyIphosphino)ferrocene (dppf) nickelalactone complex under ambient conditions. The thermodynamic product of nickelalactone ring opening was characterized as (dppe)Ni(CH(CH ₃ )C0 ₂ BAr ^f ₃ ) Without being bound by any particular theory, this is believed to be the result of β-hydride elimination and subsequent 2,1 -insertion from a transient nickel(ll) acrylate hydride intermediate. Without being bound by any particular theory it is believed that treatment of (dppe)Ni(CH(CH ₃ )C0 ₂ BAr ^f ₃ ) with a nitrogen containing base afforded a diphosphine nickel(O) n, ² -acryl borate adduct. (The Greek letter eta (η) references hapticity. η ² describes a ligand binding through 2 contiguous atoms.) Formation of the diphosphine nickel(O) r| ² -acryl borate adduct completes a net conversion of nickelalactone to acrylate species, a significant obstacle to catalytic acrylate production from C0 ₂ and ethylene. Displacement of the η ² - acrylate fragment from the nickel center was accomplished by addition of ethylene to yield a free acrylate salt and (dppf)Ni(n ² -C ₂ H ₄ ).

In some embodiments this invention comprises the composition

Structure I

and

Structure la

as well as

Structure X where Fc is ferrocene;

where Ph is a phenyl group

where P is phosphorus;

where Ar ^f is a fluorinated aryl substituent;

where B in BAr ^f ₃ is a boron linked to three fluorinated aryl substituents;

where aryl refers to a functional group or substituent derived from an aromatic ring; and,

where superscript f references a haloginated aryl, phenyl, naphthyl, thienyl, or indolyl with at least one halogen; and,

where R ¹ is, for example, C-i-C-i ₂ -alkyl such as methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 1 -(2-methyl)propyl, 2-(2-methyl)propyl, 1 -pentyl, 1 -(2- methyl)pentyl, 1 -hexyl, 1 -(2-ethyl)hexyl, 1 -heptyl, 1 -(2-propyl)heptyl, 1 -octyl, 1 - nonyl, 1 -decyl, 1 -undecyl, 1 -dodecyl, C ₃ -Ci ₀ -cycloalkyl which is unsubstituted or may bear a Ci-C ₄ -alkyl group, for example cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl and norbornyl, aryl which is unsubstituted or may bear one or two substituents selected from chlorine, C-|-C ₈ - alkyl and CrC ₈ -alkoxy, such as phenyl, napthyl, tolyl, xylyl, chlorophenyl or anisyl. Yet further included is the method of manufacturing

Structure I by _{the s} t _e p _{S 0} f reacting (dppf)nickelalactone with BAr ^f _3.

The disclosed method of manufacturing producing structure I, la or lb includes the steps of reacting a Lewis acid (LA) with (dppf)nickelalactone and BAr ^f ₃ . e I

e la

e lb

where L is selected from the group comprising butylamine, tri-n- pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n- nonylamine, tri-n-decylamine, tri-n-undecylamine, tri-n-dodecylamine, tri-n- tridecylamine, tri-n-tetradecylamine, tri-n-pentadecylamine, tri-n-hexadecylamine, tri(2-ethylhexyl)amine, dimethyldecylamine, dimethyldodecylamine,

dimethyltetradecylamine, ethyldi(2-propyl)amine, dioctylmethylamine,

dihexylmethylamine, tricyclopentylamine, tricyclohexylamine, tricycloheptylamine, tricyclooctylamine, and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl or 2-methyl-2-propyl groups,

dimethylcyclohexylamine, methyldicyclohexylamine, diethylcyclohexylamine, ethyldicyclohexylamine, dimethylcyclopentylamine, methyldicyclopentylamine, triphenylamine, methyldiphenylamine, ethyldiphenylamine, propyldiphenylamine, butyldiphenylamine, 2-ethylhexyldiphenylamine, dimethylphenylamine, diethylphenylamine, dipropylphenylamine, dibutylphenylamine, bis-(2- ethylhexyl)phenylamine, tribenzylamine, methyldibenzylamine,

ethyldibenzylamine and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl or 2-methyl-2-propyl groups. N— Cr to -Ci ₂ -alkylpiperidines, N,N'-di-Ci- to -d ₂ -alkylpiperazines, N— d- to -C-i ₂ - alkylpyrrolidines, N- d- to -C-i ₂ -alkylimidazoles, and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl or 2- methyl-2-propyl groups , 1 ,4-diazabicyclo[2.2.2]octane (DABCO) N-methyl-8- azabicyclo[3.2.1 ]octane (tropane), N-methyl-9-azabicyclo[3.3.1 ] nonane

(granatane), and 1 -azabicyclo[2.2.2]octane (quinuclidine); .

where LA comprises

BR ¹ R ² R ³ , Al R ¹ R ² R ³ , or LnX ₂ where Ln is a lanthanide.

X is a halogen, triflate, or pseudohalide (each X need not be identical), and the Lewis acid further comprising inorganic cationic salts of sodium, lithium, potassium, cesium, magnesium, calcium, barium, strontium, or transition metal.

Detailed Description of the Invention

This invention will be better understood with reference to the following definitions:

(a) Ferrocene (Fc) is an organometallic compound with the formula Fe(C ₅ H ₅ ) ₂ ;

(b) Ph shall reference a phenyl group. Thus Ph ₂ references two phenyl groups.

(c) Structure I shall mean

Structure I

Structure I is further expressed in the following configurations Structure la shall mean

Structure X is Structure lb with stated variables.

Structure X

"Ar ^f " shall be understood to represent a fluorinated aryl substituent. BAr ^f ₃ shall mean a boron linked to three fluorinated aryl substituents. Aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc. Fluorinated aryl shall mean phenyl, naphthyl, thienyl, or indolyl monosubstituted with at least one fluorine or other halogen. Particular reference is made to Structure X wherein the aryl moiety is

pentafluorophenyl.

"DBU" shall mean 1 ,8- diazabicyclo[5.4.0]undec-7-ene.

"BTPP" shall mean te/t-butylimino-tri(pyrrolidino)phosphorane.

1 ,1 '-bis(diphenylphosphino)ferrocene nickelalactone or

(dppf)Ni(CH ₂ CH ₂ C0 ₂ ) shall mean

(dppf)nickelalactone

Illustration 2

In Illustration 2, L represents a ligand which may be of the formulas

PR ¹ R ² R ³ (Formula 1 );

N R ¹ R ² R ³ (Formula 2);

R ⁴ R ⁵ P-E-PR ⁶ R ⁷ (Formula 3); and

R ⁴ R ⁵ N-E-NR ⁶ R ⁷ (Formula 4)

where R ¹ ,R ² R ³ ,R ⁴ ,R ⁵ ,R ⁶ ,R ⁷ are each independently Ci-Ci ₂ -alkyl, C3-C12- cycloalkyl, aryl, aryl-d-C ₄ -alkyl, where cycloalkyi, aryl and the aryl moiety of aryl- C-i-C-i-alkyl are unsubstituted or may bear 1 , 2, 3 or 4 identical or different substituents, for example CI, Br, I, F, Ci-Ci-alkyl or Ci-C ₄ -alkoxy.

Suitable R ¹ ,R ² R ³ ,R ⁴ ,R ⁵ ,R ⁶ ,R ⁷ radicals, for example, CrC ₁₂ -alkyl such as methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 1 -(2-methyl)propyl, 2-(2- methyl)propyl, 1 -pentyl, 1 -(2-methyl)pentyl, 1 -hexyl, 1 -(2-ethyl)hexyl, 1 -heptyl, 1 - (2-propyl)heptyl, 1 -octyl, 1 -nonyl, 1 -decyl, 1 -undecyl, 1 -dodecyl, C ₃ -Ci ₀ -cycloalkyl which is unsubstituted or may bear a C-i-C ₄ -alkyl group, for example cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl and norbornyl, aryl which is unsubstituted or may bear one or two substituents selected from chlorine, Ci-C ₈ -alkyl and Ci-C ₈ -alkoxy, such as phenyl, napthyl, tolyl, xylyl, chlorophenyl or anisyl.

Suitable examples of the bridging group E for ligands of the formula 3 and 4 include for example, ethane, methane, or propane. Particular note is made to E being ferrocene.

In addition to the ligands described above, the catalyst may also have at least one further ligand which is selected from halides, amines, carboxylates, acetylacetonate, aryl- or alkylsulfonates, hydride, CO, olefins, dienes,

cycloolefins, nitriles, aromatics and heteroaromatics, ethers, PF ₃ , phospholes, phosphabenzenes and mono-, di- and polydentate phosphinite, phosphonite, phosphoramidite and phosphite ligands.

Where base (Illustration 2) represents a depronating agent which may include an amine of the formula N R ¹ R ² R ³ (R's as defined above). By way of nonlimiting example, reference is made to Tri-n-propylamine, tri-n-butylamine, tri- n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n- nonylamine, tri-n-decylamine, tri-n-undecylamine, tri-n-dodecylamine, tri-n- tridecylamine, tri-n-tetradecylamine, tri-n-pentadecylamine, tri-n-hexadecylamine, tri(2-ethylhexyl)amine. Additionally, dimethyldecylamine, dimethyldodecylamine, dimethyltetradecylamine, ethyldi(2-propyl)amine, dioctylmethylamine,

dihexylmethylamine. Further, tricyclopentylamine, tricyclohexylamine,

tricycloheptylamine, tricyclooctylamine, and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl or 2-methyl-2-propyl groups. Yet further, dimethylcyclohexylamine, methyldicyclohexylamine, diethylcyclohexylamine, ethyldicyclohexylamine, dimethylcyclopentylamine, methyldicyclopentylamine. Noted too are triphenylamine, methyldiphenylamine, ethyldiphenylamine, propyldiphenylamine, butyldiphenylamine, 2- ethylhexyldiphenylamine, dimethylphenylamine, diethylphenylamine,

dipropylphenylamine, dibutylphenylamine, bis-(2-ethylhexyl)phenylamine, tribenzylamine, methyldibenzylamine, ethyldibenzylamine and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2- butyl or 2-methyl-2-propyl groups. N— d- to -Ci ₂ -alkylpiperidines, N,N'-di-Ci- to -Ci ₂ -alkylpiperazines, N— d- to -Ci ₂ -alkylpyrrolidines, N- d- to -C-i ₂ - alkylimidazoles, and the derivatives thereof substituted by one or more methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl or 2-methyl-2-propyl groups. 1 ,4- diazabicyclo[2.2.2]octane (DABCO) N-methyl-8-azabicyclo[3.2.1 ]octane

(tropane), N-methyl-9-azabicyclo[3.3.1 ]nonane (granatane), 1 - azabicyclo[2.2.2]octane (quinuclidine).

The base may include association with a support material capable of absorbing hydrogen cations. In some embodiments attachments of the base options listed above are usefully attached to polystyrene beads as the support material.

Anionic bases (generally in the form of salts thereof with inorganic or organic ammonium ions or alkali metals or alkaline earth metals) or neutral bases. Inorganic anionic bases include carbonates, phosphates, nitrates or halides; examples of organic anionic bases include phenoxides, carboxylates, sulfates of organic molecular units, sulfonates, phosphates, phosphonates.

Organic neutral bases include primary, secondary or tertiary amines, and also ethers, esters, imines, amides, carbonyl compounds, carboxylates or carbon monoxide. Particular note is made to base being DBU, BTPP, or carbonate.

Where LA represents a Lewis Acid which may include: BR ¹ R ² R ³ , Al R ¹ R ² R ³ , LnX ₂ where Ln includes any lanthanide metal and X includes any halogen, triflate, or pseudohalide. The Lewis Acid may include homogenous or supporting material capable of absorbing electrons from the reactor (e.g. polystyrene beads). The Lewis acid may also include inorganic cationic salts of, for example, sodium, lithium, potassium, cesium, magnesium, calcium, barium, strontium, or transition metal. Particular note is made to Lewis Acid being tris(pentafluorophenyl)borone.

Attention is drawn to the ability of a Lewis Acid to serve as an activator or co-catalyst for structures like A. Without being bound by any particular theory, it is believed this activation enables a cycle like the one above. This is significant because a Lewis acid activator permits a reaction without using a very strong base. Avoiding a strong base is advantageous since a strong base and C0 ₂ (used in making acrylate) are incompatible. Strong bases include NaOH, KOH, LiOH, RbOH, CsOH, Ca(OH) _2, Ba(OH) _2, and Sr(OH) _2.

Without being bound by any particular theory, it is thought that the early (left side) and late (right side) transitional metal complexes likely share several common intermediates on the desired catalytic pathway, but are challenged by different steps in the proposed cycle (Illustration 2). In the case of group VI metals, the oxidativ ely facile.

β-hydride

elimination

Illustration 3. Catalytic cycle for production of acrylic acid from C0 ₂ and ethylene, occurring at ambient temperature and pressures. The couplings at molybdenum and tungsten have consistently afforded acrylate products, implying that β-hydride elimination from computationally predicted metalalactone intermediates is swift. Note that the subscript "n" in L _n references number (not to be confused with Ln meaning lanthanide).

Without being bound by any particular theory it is believed that the formation of la likely proceeds via β-hydride elimination from complex lb to afford an unobserved nickel acrylate hydride intermediate (Illustration 3).

Subsequent 2,1 -insertion of the acryl borate ligand would then produce the isolated compound la. 2,1 -insertions of acrylates into late transition metal hydrides have been reported by Brookhart and others. The ring-opened species la may alternatively be prepared by addition of BAr ^f ₃ to the r| ² -acrylic acid complex, B (Illustration 3). Treatment of a benzene-c/ ₆ solution of B with one equivalent of Lewis acid results in quick consumption of the starting material and formation of complexes lb and la. This conversion is believed to occur via a short-lived intermediate (t½ ~ 15 min). The intermediate was characterized only by NMR spectroscopy, and features a pair of doublet peaks in the ³¹ P NMR spectrum at 23.42 and 33.42 ppm. The ¹⁹ F NMR resonances at 165.7, -160.2 and -134.8 ppm are significantly shifted from those of free BAr ^f ₃ and are comparable to those observed in la, suggesting the complex contains a coordinated BAr ^f ₃ unit. In addition, the observation of a broad peak at 8.45 ppm in the ¹ H NMR spectrum, similar to the chemical shift of the -OH proton in B, suggests that this unstable intermediate is simply a borane adduct of the η ² - acrylic acid complex B (lllustration3).

Lewis acid addition to B produces complexes la and lb, believed simultaneously, with the mixture gradually shifting to solely la over 4 hours. This contrasts the sequential formation of lb then la observed in BAr ^f ₃ addition to A, indicating that these two synthetic reactions enter the equilibrium process at different intermediates (Illustration 3). Our observations are most consistent with the reaction of B and BAr ^f ₃ affording the unobserved nickel(ll) acrylate hydride species, which can then diverge to form complexes la and lb with competitive rates of 1 ,2- and 2,1 -insertion, respectively. Over time the reversible reaction equilibrates to the thermodynamically more stable 2,1 -insertion product.

Deprotonation of Complex la. Having successfully induced β-hydride elimination from a stable nickelalactone species using a Lewis acid, experimental efforts were turned toward expelling acrylate from complex la. Deprotonation of la by neutral organic bases proved an effective method of accessing acrylate. Use of the sterically hindered phosphazene base, BTPP, resulted in the formation of the r| ² -acrylate complex, 3 (equation 2). Note that BTPPH+ is the conjugate acid of BTPP and has a positive charge which balances the negative charge on complex 3 in equation 2.

( ^{9 %} )

Illustration 5

over two days at ambient temperature. Complex 3 exhibited limited solubility in hydrocarbon solvents, but proved modestly soluble in ethereal and halogenated solvents. The ¹ H NMR spectrum of a chlorobenzene-c/ ₅ solution of 3 displays resonances at 2.06, 3.16 and 3.49 ppm assigned as the vinylic protons of the bound olefin. The assignments were confirmed by ¹ H- ¹³ C HSQC NMR experiments which indicate correlations to ¹³ C chemical shifts at 46.30 (CH ₂ ) and 52.45 (CH) ppm. These resonances are analogous to those reported for the η ² - acrylic acid complex B. The ¹ H NMR spectrum of 3 also exhibits the expected peaks for the conjugate acid of BTPP, including a broad N-H resonance at 4.75 ppm. The ³¹ P NMR spectrum completed the characterization with two doublets at 19.8 and 29.6 ppm assigned to the dppf ligand, as well as a singlet at 23.1 ppm from [BTPPH] ⁺ . Addition of slightly weaker bases including DBU to complex la is believed to have promited some acrylate formation, although in the case of this bicyclic amine, the r| ² -acrylate complex was not formed as selectively.

Addition of 1 eq of DBU to complex la over 2 days produced a mixture of the free [H ₂ C=CHC0 ₂ BAr ^f ₃ ] ^" [DBU] ⁺ salt, a complex analogous to 3, and some free dppf ligand. [H ₂ C=CHC0 ₂ BAr ^f ₃ ] ^" [DBU] ⁺ and [H ₂ C=CHC0 ₂ BAr ^f ₃ ] ^" [BTPPH] ⁺ salts were identified by NMR spectroscopy against independently prepared salts

synthesized through the reaction of acrylic acid with base and BAr ₃ ^f .

The observed deprotonation of la with BTPP and DBU stands in contrast to the reactivity of nickelalactone A, which similar to other diphosphine nickelacycles, is believed to requires stronger bases to induce elimination.

Without being bound by any particular theory, it is believed that the role of Lewis acid in facilitating nickelalactone deprotonation by more mild bases is of significance to the larger challenge of catalytic acrylate production from C0 ₂ and ethylene. As discussed above, several nickel compounds have been reported as capable of coupling C0 ₂ -ethylene into nickelalatone species at elevated pressures. However, inducing elimination to produce acrylate in a fashion compatible with the presence of excess C0 ₂ has remained a persistent barrier. The ability to use more mild bases for acrylate liberation enhances the viability of deprotonation techniques to overcome this barrier under high C0 ₂ pressure. The use of C0 ₂ compatible bases such as carbonates in conjunction with mild Lewis acids or frustrated Lewis pairs allows for a practical catalytic production of acrylate.

The technique of Lewis acid induced elimination from nickel lactones described here is applicable to other ligand platforms for C0 ₂ -ethylene coupling. Lewis acid, tris(pentafluorophenyl)borane, has been found to promote rapid β-hydride elimination from an isolable nickelalactone species,

(dppf)Ni(CH ₂ CH ₂ C0 ₂ ), under ambient conditions. The reversible β-hydride elimination ultimately results in formation of thermodynamically stable 2,1 - acryl borate insertion product, (dppe)Ni(CH(CH ₃ )C0 ₂ BAr ^f ₃ ) (2). Without being bound by any particular theory, it is believed that the Lewis acid activation renders 2 more facile toward deprotonation by external base than the starting

nickelalactone species. Treatment of 2 with nitrogen containing bases formed either a free acrylate salt or an n, ² -acrylate coordination complex with the nickel. Coordinated borate substituted acrylate may be substituted by ethylene.

Experimental

General Considerations. All manipulations were carried out using standard vacuum, Schlock, cannula, or glovebox techniques. Ethylene was purchased from Corp Brothers and stored over 4 A molecular sieves in heavy walled glass vessels prior to use. Argon and nitrogen were purchased from Corp Brothers and used as received. Both (dppf)Ni(CH ₂ CH ₂ C0 ₂ ) (A) and

(dppf)Ni(CH ₂ =CHC0 ₂ H) (B) were prepared according to literature procedure. All other chemicals were purchased from Aldrich, VWR, Strem, Fisher Scientific or Cambridge Isotope Laboratories. Volatile, liquid chemicals were dried over 4 A molecular sieves and distilled prior to use. Solvents were dried and

deoxygenated using literature procedures.

¹ H, ¹³ C, ¹⁹ F and ³¹ P NMR spectra were recorded on Bruker DRX 400 Avance (Billerica, MA) and 300 Avance MHz spectrometers. ¹ H and ¹³ C chemical shifts are referenced to residual solvent signals; ¹⁹ F and ³¹ P chemical shifts are referenced to the external standards C ₆ H ₅ CF ₃ , and H ₃ P0 ₄ ,

respectively. Probe temperatures were calibrated using ethylene glycol and methanol as previously described. Unless otherwise noted, all NMR spectra were recorded at 23 °C. IR spectra were recorded on a Jasco 4100 FTIR spectrometer. GC-MS data were recorded using a Hewlett-Packard (Agilent)

GCD 1800C GC-MS spectrometer. X-ray crystallographic data were collected on a Bruker D8 QUEST diffractometer. Samples were collected in inert oil and quickly transferred to a cold gas stream. The structures were solved from direct methods and Fourier syntheses and refined by full-matrix least-squares procedures with anisotropic thermal parameters for all non-hydrogen atoms. Elemental analyses were performed at Robertson Microlit Laboratories, Inc., Madison, NJ or Atlantic Microlab, Inc., Norcross, GA.

Preparation of (dppf)Ni(CH ₂ CH2C02B(C ₆ F5)3) (lb), Example 1 : A 20 mL scintillation vial was charged with 0.013 g (0.019 μηποΙ) (dppf)Ni(CH ₂ CH ₂ C0 ₂ ) (A), 0.010 g (0.019 μιτιοΙ) of B(C ₆ F ₅ ) ₃ and approximately 2 ml_ of CH ₂ CI ₂ . The deep orange solution was stirred for 5 minutes and the volatiles removed under vacuum. The resulting solid was then dissolved in C ₆ D ₆ for NMR study. Identical NMR spectra may be taken at 10 °C to slow the conversion of lb to la for longer timescale experiments. ¹ H NMR (C ₆ D ₆ ): δ 0.84 (m, 2H, Ni-a-CH ₂ ), 2.21 (m, 2H, Νι-β~ΟΗ ₂ ), 3.36 (s, 2H, CpH), 3.62 (s, 2H, CpH), 3.72 (s, 2H, CpH), 4.12 (s, 2H, CpH), 8.98-7.67 (Ph). ³ P{ H} NMR (C ₆ D ₆ ): δ 15.7 (d, ² J _P)P 15.8Hz, 1 P, PPh ₂ ), 34.3 (d, ² J _P) p 15.8 Hz, 1 P, PPh ₂ ). ⁹ F NMR (C ₆ D ₆ ): δ -166.60 (t), -161 .47 (t), - 135.77 (d). A basic process of preparing lb comprises the steps of

(a) combining an organometalic compound such as (dppf)Ni(CH ₂ CH ₂ C0 ₂ ), a Lewis acid such as B(C ₆ F ₅ )3 nd, a solvent such as CH ₂ CI ₂ ;

(b) stirring for from about 1 to about 5 minutes;

(c) removing volatiles under vacuum. Precipitating lb out as a solid.

Preparation of other embodiments of lb. Example 2. A 20 mL scintillation vial is charged with 0.019 μιτιοΙ of (dppe)Ni(CH ₂ CH ₂ C0 ₂ ) (A) (where dppe is 1 ,2-Bis(diphenylphosphino)ethane), 0.019 μιτιοΙ of B(C ₆ F ₅ ) ₃ and approximately 2 mL of CH ₂ CI ₂ , chlorobenzene, or other polar solvent. The solution is stirred for 5 minutes-12 hours and the volatiles removed under vacuum. The resulting solid 1 b is then dissolved in organic solvent for NMR study or use.

Preparation of other embodiments of lb. Example 3. A 20 mL scintillation vial is charged with 0.019 μιτιοΙ of (PMe ₃ )2Ni(CH2CH ₂ C02) (A) (where PMe ₃ is trimethylphosphine), 0.019 μιτιοΙ of B(C ₆ F ₅ )3 and approximately 2 mL of CH ₂ CI ₂ , chlorobenzene, or other polar solvent. The solution is stirred for 5 minutes-12 hours and the volatiles removed under vacuum. The resulting solid 1 b is then dissolved in organic solvent for NMR study or use.

Preparation of (dppf)Ni(CH(CH ₃ )(C02B(C ₆ F5)3) (la) Example 4: A 20 mL container was charged with 0.096 g (0.142 μηποΙ) (dppf)Ni(CH ₂ =CHC0 ₂ H) (B), 0.073 g (0.143μιτιοΙ) of B(C ₆ F ₅ )3 nd approximately 5 mL of toluene. The orange solution was stirred for one day and the volatiles removed under vacuum. The resulting solid was washed with 2 mL of pentane, extracted with diethyl ether, and chilled at -35 °C to afford 128 mg (76%) of la as orange crystals. Anal.

Calcd. for C55H ₃ 2BF ₁₅ FeNi02P2: C, 55.18; H, 2.69. Found: C, 55.50; H, 2.67. ¹ H NMR (C ₆ D ₆ ): δ 0.23 (dd, 3H, CH ₃ , J _HjH 7.0 Hz, J _P>H 7.8 Hz, Νϊ-β-ΟΗ ₃ ), 2.03 (m, 1 H, Ni-a-CH), 3.59 (s, 1 H, CpH), 3.67 (s, 1 H, CpH), 3.71 (s, 1 H, CpH), 3.73 (s, 2H, CpH), 3.81 (s, 1 H, CpH), 4.05 (s, 1 H, CpH), 4.35 (s, 1 H, CpH), 6.91 -7.1 1 (m, 12H, CpH), 7.34-7.39 (m, 2H, Ph), 7.51 -7.59 (m, 4H, Ph), 7,67-7.70 (m, 2H, Ph). ³ P{ ¹ H} NMR (C ₆ D ₆ ): 5 22.4 (d, ² J _PjP 20.0 Hz, 1 P, PPh ₂ ), 36.2 (d, ² J _P>P 20.0 Hz, 1 P, PPh ₂ ). ¹³ C{ H} NMR (C ₆ D ₆ ): δ 12.36 (Ni-CH-CH ₃ ), 34.58 (Ni-CH), 73.36, 74.81 , 75.04, 75.40, 76.18 (Cp), 128.66-129.15, 131 .36, 133.03, 133.15, 133.85, 133.98, 133.12, 134.12, 134.24, 134.74, 134.86 (aryl) 181 .20 (C0 ₂ ). ^{1 S} F NMR (C ₆ D ₆ ): δ -166.60 (t), -161 .02 (t), -135.37 (d). IR (KBr): v _c= o = 1644 cm ^"1 .

Preparation of other embodiments of la. Example 5. A 20 mL scintillation vial iss charged with 0.142 μιηοΙ of (dppe)Ni(CH ₂ =CHC0 ₂ H) (B)

(where dppe is 1 ,2-Bis(diphenylphosphino)ethane), 0.143μιτιοΙ of B(C ₆ F ₅ ) ₃ and approximately 5 mL of toluene, CH ₂ CI ₂ , chlorobenzene, or other polar solvent. The solution is stirred for one day to one week. After that the volatiles are removed under vacuum. The resulting solid is washed with 2 mL of pentane, diethyl ether, or toluene to afford la as solid. Preparation of another embodiment of la. Example 6. A 20 mL scintillation vial is charged with 0.142 μιηοΙ of (PMe ₃ ) ₂ Ni(CH ₂ =CHC0 ₂ H) (B) (where PMe ₃ is trimethylphosphine), 0.143μιτιοΙ of B(C ₆ F ₅ ) ₃ and approximately 5 mL of toluene, CH ₂ CI ₂ , chlorobenzene, or other polar solvent. The solution is stirred for one day to one week and the volatiles removed under vacuum. The resulting solid is washed with 2 mL of pentane, diethyl ether, or toluene to afford la as solid.

Preparation of [(dppf)Ni(n ² -CH ₂ =CH-C0 ₂ B(C ₆ F5) ₃ )][HBTPP] (B)

Example 7: A 20 mL scintillation vial was charged with 0.035 g (0.029μιηοΙ) of (dppf)Ni(CH(CH ₃ )(C0 ₂ B(C ₆ F5)3) (la), 9 pL (0.029μιηοΙ) of BTPP and

approximately 1 mL of benzene. The solution was stirred for two days resulting in precipitation of a yellow solid. The solid was collected by filtration to afford 40 mg (91 %) of 3 as a yellow powder. The material may be extracted with THF if necessary to remove trace nickel metal particulates. Anal. Calcd. for

C ₇₁ H ₆ 5BF ₁₅ FeNiN ₄ 0 ₂ P3: C, 56.49; H, 4.34; N, 3.71 . Found: C, 55.96; H, 4.48; N, 3.51 . ¹ H NMR (C ₆ D ₅ CI): δ 0.97 (s, 9H, N-C(CH ₃ ) ₃ ), 1 .39 (s, 12H, Ν-β-ΟΗ ₂ ), 2.06 (m, 3.49 (m, 1 H, H), 3.99 (s, 1 H, CpH), 4.02 (s, 2H, CpH), 4.47 (s, 1 H, CpH), 4.62 (s, 1 H, CpH), 4.75 (br, 1 H, NH) 6.92-7.24 (m, 12H, Ph), 7.56-7.99 (m, 8H, Ph). ³¹ P{ ¹ H} NMR (C ₆ D ₅ CI): δ 19.8 (d, ² JP,P 22.8 Hz, 1 P, PPh ₂ ), 23.1 (s, 1 P, [HBTPP] ⁺ ), 29.6 (d, ² J _P , _P 22.8 Hz, 1 P, PPh ₂ ). ¹³ C{ ¹ H} NMR (C ₆ D ₅ CI): δ 26.01 (N- -CH ₂ ), 30.93 (N-C(CH ₃ ) ₃ ), 46.30 (n ² -CH ₂ =CH), 47.40 (N-a-CH ₂ ), 52.45 (n ² -CH ₂ =CH), 70.09, 70.44, 72.62, 73.03, 73.46, 74.78, 74.90 (Cp), 127.55, 131 .50, 131 .94, 133.47, 135.05, 136.03, 136.38, 147.80, 149.37 (aryl) three aryl signals not located, 178.33 (C0 ₂ ). ¹⁹ F NMR (C ₆ D ₅ CI): δ -134.00 (d), -164.42 (t), -168.24(t). IR (KBr): v _c= o = 1642 cm ^"1 . Preparation of another embodiment of B. Example 8. A 20 mL scintillation vial is charged with 0.029μηποΙ of (dppe)Ni(CH(CH ₃ )(CO2B(C ₆ F5)3) (la), (where dppe is 1 ,2-Bis(diphenylphosphino)ethane) 9 μΙ_ (0.029μιτιοΙ) of BTPP and approximately 1 mL of benzene, toluene, chlorobenzne or other organic solvent. The solution is stirred for two days to one week. The solvent is removed and the solid collected. Extraction and filtration with benzene, toluene, chlorobenzne or other organic solvent is used to remove trace nickel metal particulates if present.

Preparation of another embodiment of B. Example 9. A 20 mL scintillation vial is charged with 0.029μηποΙ of (PMeafeN CHiCHaXCCkBiCeFsfe) (la), (where PMe ₃ is trimethylphosphine)) 9 μί (0.029μηποΙ) of BTPP and approximately 1 mL of benzene, toluene, chlorobenzne or other organic solvent. The solution is stirred for two days to one week. The solvent is removed and the solid collected. Extraction and filtration with benzene, toluene, chlorobenzne or other organic solvent is used to remove trace nickel metal particulates if present.

Preparation of an embodiment of A. Preparation of (dcpe)Ni(KC,KO- CH ₂ CH ₂ COO) (hereinafter "1-Ylactone") Example 10. This species was prepared by modification of procedure described by Hoberg and co-workers (Hoberg, H et al., Organomet. Chem. 1983, 251, C51 . ) using Ni(COD) ₂ as the metal source. A 50 mL heavy-walled glass reaction vessel was charged with 0.178 g (0.421 mmol) of dcpe, 0.1 18 g (0.429 mmol) of Ni(COD) ₂ and

approximately 6 mL of THF. On a high-vacuum line, 5 equiv of ethylene (390 Torr in 101 mL) followed by 5 equiv of carbon dioxide (390 Torr in 101 mL) was admitted to the reaction mixture at -196 °C via a calibrated gas bulb. After the mixture was stirred for 1 day at 50 °C, the volatiles were removed in vacuo. The residue was washed with approximately 3 mL of diethyl ether, 1 mL of toluene, and extracted with THF to remove trace nickel metal particulates. The extract was then dried to afford 0.208 g (89%) of 1 -ylactone with good purity. The material may be further purified by layering pentane on a concentrated THF solution and chilling at -35 °C. The spectral data below are in agreement with those previously reported by Yakelis (N. A.Yakelis, R. G. Bergman,

Organometallics 2005, 24, 3579.).

Anal. Calcd for C29H52N1O2P2: C, 62.94; H, 9.47. Found: C, 63.21 ; H, 9.77.

¹ H NMR (C ₆ D ₆ ): δ 0.89 (m, 2H, (PCy ₂ )), 1 .00 (m, 2H, Ni-a-CH ₂ ), 1 .02-1 .65 (42H, PCy ₂ ), 2.02 (m, 2H, PCH ₂ CH ₂ P), 2.20 (m, 2H, PCH ₂ CH ₂ P), 2.85 (m, 2H, Ni-β- CH ₂ ). ¹³ C{ ¹ H} NMR (C ₆ D ₆ ): δ 1 1 .64 (Ni- a -CH ₂ ), 24.70, 26.42, 27.13-27.47, 29.17 (PCy ₂ -CH ₂ ), 29.45 (PCH ₂ CH ₂ P), 29.70 (PCH ₂ CH ₂ P), 33.80, 35.30 (PCy ₂ - CH), 37.76 (Νί-β-ΟΗ ₂ ), 188.83 (C0 ₂ ). ³¹ P{ ¹ H} NMR (C ₆ D ₆ ): δ 63.65 (bs s,1 P, PCy ₂ ), 69.79 (br s, 1 P, PCy ₂ ).

Preparation of an embodiment of A. Preparation of (dcpm)Ni(KC,KO- CH ₂ CH ₂ COO) (hereinafter "2-Ylactone") Example 11. A 50 ml_ heavy-walled glass reaction vessel was charged with 0.309 g (0.757 mmol) of dcpm, 0.207 g (0.753 mmol) of Ni(COD) ₂ and approximately 6 ml_ of THF. On a high-vacuum line, ethylene (420 Torr in 101 ml_) followed by carbon dioxide (700 Torr in 101 ml_) were admitted to the reaction mixture at -196 °C via a calibrated gas bulb. After the mixture was stirred for 1 day at 50 °C, the volatiles were removed in vacuo. The residue was washed with diethyl ether and extracted with THF to remove trace nickel metal particulates. The extract was then dried to afford 0.190 g (47%) of 2-Ylactone as orange powder containing minor amounts of

(dcpm)Ni(COD). The material may be further purified by layering pentane on a concentrated THF solution and chilling at -35 °C. Alternatively 2-ylactone may be obtained by charging a 20 ml_ scintillation vial with 0.152 g (0.372 mmol) of dcpm, 0.103 g (0.374 mmol) of Ni(COD) ₂ , and approximately 3 ml_ of THF. After the solid dissolved, 29 μΙ_ (0.423 mmol) of acrylic acid was injected into the reaction mixture. The mixture was stirred at ambient temperature for 30 minutes and the desired product isolated as described above. Anal. Calcd for

C28H50N1O2P2: C, 62.35; H, 9.34. Found: C, 62.08; H, 9.13. ¹ H NMR (C ₆ D ₆ ): δ 1 .00 (m, 2H, Ni-a-CH ₂ ), 1 .03-1 .66 (40H, PCy ₂ , (PCy ₂ )), 1 .95-2.08 (6H, PCH ₂ P & PCy ₂ ), 2.65 (m, 2H, Νί-β-ΟΗ ₂ ). ¹³ C{ ¹ H} NMR (C ₆ D ₆ ): δ 8.24 (Ni- a -CH ₂ ), 25.83, 26.25, 27.28-27.43, 28.67, 29.27, 29.56, 29.69, 30.23 (PCy ₂ -CH ₂ ), 34.41 , 34.57 (PCy ₂ -CH), 37.37 (Νί-β-ΟΗ ₂ ), one quaternary signal not located. ³¹ P{ ¹ H} NMR (C ₆ D ₆ ): 5 -7.1 1 (d, ² J _P . _P = 23.3Hz , 1 P, PCy ₂ ), 1 7.73 (d, ² J _P . _P = 23.3Hz, 1 P, PCy ₂ ).

Preparation of an embodiment of 1 b. Preparation of [(dcpe)Ni(KC,KO- CH ₂ CH ₂ COONa)][BAr ₄ ^F ] (hereinafter "1 -YlactoneNa") Example 12. A 20 mL scintillation vial was charged with 0.058 g (0.105 mmol) of 1 -ylactone, 0.099 g (0.1 1 2 mmol) of NaBAr ₄ ^F , and approximately 3 mL of THF. After the mixture was stirred at ambient temperature for 1 0 minutes, the volatiles were removed in vacuo. The residue was washed with benzene and extracted with diethyl ether. Concentrating the solution, layering with pentane and chilling to -35 °C afforded 0.145 g (96%) of 1 -vlactoneNa as orange crystals. Anal. Calcd for

C ₆ i H ₆₄ BF ₂₄ NaNi0 ₂ P ₂ : C, 50.89; H, 4.48. Found: C, 50.94; H, 4.71 . ¹ H NMR (C ₆ D ₅ Br) : δ 0.82 (m, 2H, Ni-a-CH ₂ ), 1 .1 -1 .72 (44H, PCy ₂ ), 1 .94, 2.02 (m, 4H, PCH ₂ CH ₂ P), 2.31 (m, 2H, Ni- β -CH ₂ ), 7.63 (s, 4H, BAr ₄ ^F ), 8.1 8 (s, 8H, BAr ₄ ^F ). ¹³ C{ ¹ H} NMR (C ₆ D ₅ Br) : δ 1 2.1 1 (Ni- a -CH ₂ ), 25.31 -25.78, 26.57-26.93, 28.60, 28.88, 29.37, 29.80 (PCy ₂ -CH ₂ ), 33.49, 35.43 (PCy ₂ -CH), 36.67 (Νί-β-ΟΗ ₂ ), 1 1 7.48, 1 23.26, 134.86, 1 62.1 1 (BAr ₄ ^F ), one aryl and one quaternary signal not located. ³¹ P{ ¹ H} NMR (C ₆ D ₅ Br): δ 60.62 (s, 1 P, PCy ₂ ), 70.93 (s, 1 P, PCy ₂ ). ¹⁹ F NMR (C ₆ D ₅ Br) : -62.95 (s).

Preparation of an embodiment of 1 b. Preparation of

[(dcpm)Ni(KC,KO-CH ₂ CH ₂ COONa)][BAr ₄ ^F ] (hereinafter "2-YlactoneNa")

Example 13. A 20 mL scintillation vial was charged with 0.040 g (0.074 mmol) of 2-Ylactone, 0.073 g (0.082 mmol) of NaBAr ₄ ^F , and approximately 3 mL of THF. After the mixture was stirred at ambient temperature for 10 minutes, the volatiles were removed in vacuo. The residue was washed with benzene and extracted with diethyl ether. Layering the concentrated diethyl ether solution with pentane and chilling at -35 °C afforded 0.103 g (97%) of 2-ylactoneNa as orange crystals. ¹ H NMR (C ₆ D ₅ Br): δ 0.71 (m, 2H, Ni-a-CH ₂ ), 1 .04-1 .94 (m, 44H, PCy ₂ ), 2.01 (m, 2H, Νί-β-ΟΗ ₂ ), 2.1 3 (m, 2H, PCH ₂ P) 7.63 (s, 4H, BAr ₄ ^F ), 8.18 (s, 8H, BAr ₄ ^F ). ¹³ C{ ¹ H} NMR (C ₆ D ₅ Br) : 5 7.42 (Ni-a-CH ₂ ), 25.1 3, 25.63, 26.31 , 26.66-26.93, 28.28, 29.26, 29.34 (PCy ₂ -CH ₂ ), 29.09 (PCH ₂ P), 34.28, 34.52 (PCy ₂ -CH), 36.1 7 (Ni- β -ΟΗ ₂ ), 1 1 7.48, 123.26, 1 34.86, 1 62.1 1 (BAr ₄ ^F ), one aryl and one

quaternary signal not located. ³¹ P{ ¹ H} NMR (C ₆ D ₅ Br) : δ -8.70 (d, ² J _P . _P = 35.5 Hz, 1 P, PCy ₂ ), 1 9.24 (d, ² J _P . _P = 35.5 Hz, 1 P, PCy ₂ ). ¹⁹ F NMR (C ₆ D ₅ Br): -62.95 (s).

Preparation of an embodiment of B. Preparation of (dcpe)Ni(n ² - C,C- CH ₂ =CHC0 ₂ H) (hereinafter "1 -AA") Example 14. A 20 mL scintillation vial was charged with 0.1 29 g (0.305 mmol) of dcpe, 0.084 g (0.305 mmol) of Ni(COD) ₂ , and approximately 4 mL of THF. After the solid dissolved, 25 L (0.364 mmol) of acrylic acid was injected into the reaction mixture. The mixture was stirred at ambient temperature for 1 hour, resulting in precipitation of a yellow solid. The solid was filtered and washed with approximately 3 mL of THF to afford 0.1 30 g (82%) of (dcpe)Ni( ² -CH ₂ CHCOOH) as a yellow powder. ¹ H NMR (C ₆ D ₅ Br): δ 1 .02-2.02 (48H, PCy ₂ & PCH H ₂ P), 2.08 (br m, 1 H, r] ² -CH ₂ CH), 2.40 (br m, 1 H, η ² -ΟΗ ₂ ΟΗ), 3.31 (br m, 1 H, r] ² -CH ₂ CH), 1 2.33 (br s, 1 H, COOH) ¹³ C{ ¹ H} NMR (C ₆ D ₅ Br) : 5 20.1 1 -27.21 (PCy ₂ -CH ₂ & P CH ₂ CH ₂ P) 25.81 (n ² -CH ₂ CH), 29.61 , 32.1 1 (PCy ₂ -CH), 37.51 (r] ² -CH ₂ CH), one quaternary COOH signal not located. ³¹ P{ ¹ H} NMR (C ₆ D ₅ Br): 5 61 .30 (d, ² J _P . _P = 48.1 Hz, 1 P, PCy ₂ ), 72.50 (d, ² J _P . _P = 48.1 Hz, 1 P, PCy ₂ ).

Preparation of an embodiment of 1 a. Preparation of (dcpe)Ni(KC,KO- CH(CH ₃ )COO) (hereinafter "1 ^lactone") Example 15. This species may be generated by either thermolysis of 1 -ylactone or 1 -AA. Since the isomerization from 1 -AA provides a higher kinetic yield of 1 - iactone, it was used in isolation of small quantities of the pure compound. A 20 mL scintillation vial was charged with 0.092 g (0.21 8 mmol) of dcpe, 0.060 g (0.21 8 mmol) of Ni(COD) ₂ , and approximately 1 5 mL of benzene. 1 6 L (0.233 mmol) of acrylic acid was injected into the reaction mixture. After the mixture was stirred at ambient temperature for 1 day, the volatiles were removed in vacuo. The residue was washed with pentane and extracted with toluene to afford 0.050 g mixture of 1 ^lactone and 1 - Ylactone. The mixture was re-dissolved in THF and layered with pentane to afford 0.015 g (12%) of pure 1 ^lactone as orange crystals. Anal. Calcd for

C29H52N1O2P2: C, 62.94; H, 9.47. Found: C, 63.21 ; H, 9.21 . ¹ H NMR (C ₆ D ₆ ): δ

0.98.1 .85 (44H, PCy ₂ ), 1 .47 (m, 3H, Ni- β-ΟΗ ₃ ), 2.05-2.16 (m, 4H, PCH ₂ CH ₂ P), 2.30 (br m, 1 H, Ni-a-CH). ¹³ C{ ¹ H} NMR (C ₆ D ₆ ): δ 16.62 (Ni- β-ΟΗ ₃ ), 26.17-26.57, 27.06-27.57, 29.14-29.85, 30.33, 31 .26 (PCy ₂ -CH ₂ ), 28.1 1 (Ni-a-CH), 33.87, 36.60 (PCy ₂ -CH) 180.21 (C0 ₂ ). ³¹ P{ ¹ H} NMR (C ₆ D ₆ ): δ 64.36 (d, ² J _P . _P = 8.7 Hz, 1 P, PCy ₂ ), 71 .09 (d, ² J _P . _P = 8.7 Hz, 1 P, PCy ₂ ).

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