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DESCRIZIONE

The invention relates to monocarbonyl complexes of ruthenium and osmium with bi- and tridentate nitrogen and phosphine ligands. The invention relates to methods for preparing these complexes and the use of these complexes, isolated or prepared in situ, as catalysts for reduction reactions of ketones and aldehydes both via transfer hydrogenation or hydrogenation with hydrogen.

State of the art

The carbonyl compounds (aldehydes and ketones) can be easily reduced to alcohols by molecular hydrogen (hydrogenation) or hydrogen donor molecules (transfer hydrogenation) through the use of catalysts based on rhodium, iridium, iron, ruthenium and osmium.

The development of complexes that catalyze the chemo- and stereo-selective reduction of carbonyl compounds is a subject of considerable academic and industrial interest, a target which can be achieved through the fine-tuning of the ligands of the complexes. The hydrogenation, which entails the use of hydrogen under pressure, is an industrial process for the synthesis of alcohols. A significant breakthrough for the development and application of this process was given in the late '90s by a new class of ruthenium complexes of formula RuCI ₂ (P)2(diamine) and RuCI ₂ (PP)(diamine) (P=phosphine and PP=diphosphine) for the catalytic enantioselective hydrogenation of ketones. By using a suitable combination of chiral diphosphine and diamine ligands, these complexes were proven to efficiently catalyze the asymmetric reductions of carbonyl compounds with production of chiral alcohols with high enantiomeric excess.

In addition to hydrogenation, the transfer hydrogenation reaction has also been developed using 2-propanol or formic acid as hydrogen source, with the advantage of employing non-pressure systems and reducing the risk.

In 2004 Baratta and collaborators have developed ruthenium complexes containing phosphines and bi- and tri-dentate aminopyridine ligands which show high catalytic activity in hydrogenation and transfer hydrogenation reactions.

Recently, the complexes irans-RuCI ₂ (CO)(NN)(PR ₃ ) (R = Ph, p-tolyl; NN = ethylenediamine, 2-aminomethylpyridine and bipyridine) were isolated and they were found active in the transfer hydrogenation of ketones (D. A. Cavarzan et al., Polyhedron 2013, 62, 75). It is worth noting that the carbonyl complexes [RuX(CO)(NN)(PP)]CI (X = CI, H; NN = ethylenediamine or 2-aminomethylpyridine) and RuCI(CP)(CO)(NN) containing a cyclometallated phosphine (CP) isolated by Baratta and co-workers display high catalytic activity in the transfer hydrogenation of ketones (S. Zhang et al., Organometallics 2013, 32, 5299; W. Baratta et al., Angew. Chem. Int. Ed. 2004, 43, 3584; W. Baratta et al., Organometallics 2004, 23, 6264 and WO2005/051965). Complexes of the formula RuCl ₂ (CO)(dmf)(PP) have been found active in hydrogenation, transfer hydrogenation, hydroformylation and carbonylation reactions (WO2012/123761 A1 ).

The interest in these systems stems from the fact that the presence of a Ru-CO bond makes the catalyst more robust and less sensitive to the decarbonylation reactions of the substrates which can deactivate the catalysts, preventing their use in very low quantities.

Moreover, to make the reduction of carbonyl compounds to alcohols economically competitive, via transfer hydrogenation or hydrogenation, the development of catalysts with high chemo- and stereoselectivity is a crucial issue. Furthermore, the catalysts have to display high productivity and should be easily prepared from commercial available starting material through simple and safe synthetic routes.

The purpose of the present invention relates to the synthesis of complexes of ruthenium and osmium containing a CO ligand in combination with bidentate and tridentate nitrogen ligands and achiral or chiral phosphines. These complexes can be used as catalysts in the (asymmetric) reduction of carbonyl compounds by transfer hydrogenation or hydrogenation with molecular hydrogen.

A further object of the present invention is to obtain ruthenium (II) and osmium (II) complexes which can be generated in situ during the reduction of carbonyl compounds or by transfer hydrogenation or hydrogenation with molecular hydrogen.

Summary of the invention

In order to achieve the purposes mentioned above the inventors have identified in a series of monocarbonyl complexes of ruthenium and osmium, containing nitrogen and phosphine ligands, the solution for obtaining catalysts with high catalytic activity in hydrogenation reactions with molecular hydrogen and transfer hydrogenation of carbonyl compounds to alcohols.

Accordingly, the present disclosure refers to a pentacoordinate or hexacoordinate complex of formula (1 ): [MXY _a (CO)L _b L' _c ]Wd (1 )

wherein

M = Ru or Os;

a, b and d are independently 0 or 1 ;

c is 1 or 2;

X, Y are independently selected among halides, hydride, C1 -C20 carboxylates and C1 - C20 alkoxides;

W is selected among halides, C1 -C20 carboxylates and C1 -C20 alkoxides;

L is a nitrogen-containing ligand selected among:

(I) a NN compound of formula la to lc:

(II) a HCNN compound of formula lla - Mb and a CNN ligand of formula lie - lid:

(III) a HCN compound of formula Ilia

wherein

R ¹ - R ¹⁵ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups;

L' is at least one phosphorus-containing ligand selected among: - a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active phosphine selected among (S)- neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '- binaphthyl;

- a diphosphine (PP) selected among: a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active diphosphine selected from the group consisting of (fl)-(6,6'-dimethoxybiphenyl-2,2'- diyl)bis(diphenylphosphine], (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis(diphenylphosphine), (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5-dimethylmethyl)phosphi ne], (ft)-1 -{-2- [diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5-dimethyl- 4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane;

- a HCP compound of formula (IVa) and a CP ligand of formula (IVb)

a PNN compound of formula (V)

wherein

pj2i _ pj29 _are j _nc | _e p _enc | _en tiy selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups;

provided that:

- when a = b = c = 1 ; d = 0; X = Y = CI; L is ethylenediamine or 2-(aminomethyl)pyridine or 2,2'-bipyridine or 4,4'-dimethyl-2,2'-bipyridine, L' is not a phosphine (P) of formula p _R 16 _R 17 _R 18 _{in wh ich R} 16 _{= R} 17 _{= R} 18 _{= pheny} | _{Qr p} _ _to | _y | _; - when a = 0; b = c = d= 1 ; X = W = Cl or X = H and W = CI, L = ethylenediamine or 2- (aminomethyl)pyridine, L' is not Ph ₂ P(CH2CH ₂ CH2)PPh2;

- when a = d = 0; b = c = 1 ; X = CI; L = ethylenediamine or 2-(aminomethyl)pyridine, L' is not a ligand (CP) of formula (IVb) in which R ²¹ = R ²² = phenyl and R ²³ = methyl; and - when a, b and d are 0, c is 2, X is CI and R ²³ is -CH ₃ , R ²¹ and R ²² are not phenyl groups.

In a further aspect, the present disclosure refers to the use of said ruthenium or osmium complexes as catalyst or pre-catalyst for the reduction reaction of ketones or aldehydes to alcohols by transfer hydrogenation or hydrogenation with molecular hydrogen.

This and other aspects as well as the characteristics and advantages of the present invention will be more apparent from the detailed description below and by the preferred embodiments given as non-limiting illustrations of the invention itself.

Description of the invention

As used therein, "aliphatic group" refers to acyclic or cyclic, linear or branched, saturated or unsaturated hydrocarbons, excluding aromatic groups.

As used therein, "substituted aliphatic group" refers to an aliphatic group in which at least one hydrogen atom is replaced by at least one substituent group selected among -OR, -NRR', -NRCOR', -NO ₂ , -NH ₂ , -COR, -COOR, -CONRR' and halides, wherein R and R' are equal or different and can be a H or a C1 -C20 aliphatic or aromatic group. As used therein, "aromatic group" also include aromatic compounds substituted with aliphatic groups.

As used therein, "substituted aromatic group" refers to an aromatic group in which at least one aromatic hydrogen atom is replaced with at least one substituent group selected among -R, -OR, -NRR', -NRCOR', -NO ₂ , -NH ₂ , -COR, -COOR, -CONRR' and halides, wherein R and R' are equal or different and can be a H or a C1 -C20 aliphatic or aromatic group.

As used therein, "heteroaromatic group" refers to aromatic groups in which at least one carbon atom which is part of the aromatic ring is replaced with one heteroatom selected among N, S, O and P.

As used therein, "hydrogen-donor" refers to a compound that transfers a hydrogen atom to another compound.

As used therein, "(transfer)hydrogenation" refers to hydrogenation with molecular hydrogen or to transfer hydrogenation using a hydrogen donor compound. In the present description and appended claims the abbreviations listed in Table 1 are used:

Table 1. Abbreviation of the nitrogen and phosphorus ligands

The present disclosure refers to a pentacoordinate or hexacoordinate complex of formula (1 ): [MXY _a (CO)L _b L' _c ]W _d (1 )

wherein

M = Ru or Os;

a, b and d are independently 0 or 1 ;

c is 1 or 2; X, Y are independently selected among halides, hydride, C1 -C20 carboxylates and C1 - C20 alkoxides;

W is selected among halides, C1 -C20 carboxylates and C1 -C20 alkoxides;

L is a nitrogen-containing ligand selected among:

(I) a NN compound of formula la to lc:

(II) a HCNN compound of formula lla - Mb and a CNN ligand of formula lie - lid:

a HCN compound of formula Ilia

wherein

R ¹ - R ¹⁵ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ and R ⁸ -R ¹⁵ may be H and/or R ⁷ may be 4-methyl;

L' is at least one phosphorus-containing ligand selected among:

- a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active phosphine selected among (S)- neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '- binaphthyl;

- a diphosphine (PP) selected among: a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active diphosphine selected from the group consisting of (ft)-(6,6'-dimethoxybiphenyl-2,2'- diyl)bis(diphenylphosphine], (fi)-(1 ,1 '-binaphthalene-2,2'-diyl)bis(diphenylphosphine), (fl)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5-dimethylmethyl)phosphi ne], (fl)-1 -{-2- [diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, (ft)-1 -{-2-[bis(3,5-dimethyl- 4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane;

- a HCP compound of formula (IVa) and a CP ligand of formula (IVb)

wherein

R ²¹ - R ²³ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, more preferably R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be independently selected among phenyl and cyclohexyl group - a PNN compound of formula (V)

wherein

R ²⁴ - R ²⁹ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ²⁴ and R ²⁷ -R ²⁹ may be H and/or R ²⁵ and R ²⁶ may be a C1 - C20 aromatic group, more preferably a phenyl group;

provided that: - when a = b = c = 1 ; d = 0; X = Y = CI; L is ethylenediamine or 2-(aminomethyl)pyridine or 2,2'-bipyridine or 4,4'-dimethyl-2,2'-bipyridine, L' is not a phosphine (P) of formula p _R 16 _R 17 _R 18 _{in wh ich R} 16 _{= R} 17 _{= R} 18 _{= pheny} | _{Qr p} _ _to | _y | _;

- when a = 0; b = c = d= 1 ; X = W = Cl or X = H and W = CI, L = ethylenediamine or 2- (aminomethyl)pyridine, L' is not Ph ₂ P(CH2CH ₂ CH2)PPh2;

- when a = d = 0; b = c = 1 ; X = CI; L = ethylenediamine or 2-(aminomethyl)pyridine, L' is not a ligand (CP) of formula (IVb) in which R ²¹ = R ²² = phenyl and R ²³ = methyl; and

- when a, b and d are 0, c is 2, X is CI and R ²³ is -CH ₃ , R ²¹ and R ²² are not phenyl groups.

In complexes of formula (1 ), when c = 2 and L' represents two phosphorus-containing ligands independently selected among the phosphorus-containing compounds listed above, when one L' is CP and one L' is HCP, the complex of formula (1 ) is pentacoordinate complex.

The high modularity of the nitrogen-containing ligands (la-c), (lla-d) and (Ilia) in combination with phosphines (P), diphosphines (PP), HCP phosphines and PNN phosphines, allows to obtain a large number of well-defined catalysts displaying high chemo- and stereoselectivity.

For the purposes of the present invention, from the combination of the different meanings of X, Y, W, L, and L', the complexes of sub-formulas (VI - XIV) given below may be obtained, which are encompassed by the general formula (1 ).

According to an embodiment, the bidentate (NN) ligands of type (la-c) have the ability, through the nitrogen atoms of a -NH ₂ group or of a heterocycle in combination with monodentate phosphines, to coordinate the metal. Thus, the present disclosure may refer to a complex of formula (VI)

MXY(CO)(NN)(P) (VI)

wherein M, X, Y, (NN) and (P) are as defined above, provided that when X and Y are CI, _R 16 _ _R 18 _{are not} ph _en y| _or p-tolyl groups.

According to a specific embodiment, the present disclosure may refer to complexes of formula (VI) wherein M, X, Y, (NN) and (P) are as defined above, provided that when X and Y are CI, R ¹⁶ - R ¹⁸ are not aromatic groups.

Complexes of formula (VI) can be obtained as a mixture of frans-isomers (eg. complex 4 and 6 below) and c/ ^' s-isomers (eg. complex 5 and 7).

The present disclosure also refers to a process to obtain complexes of formula (VI) comprising reacting a compound of formula MXY(CO)(PPh ₃ ) ₂ , or of formula MXY(CO)(PPh ₃ ) ₂ (dmf), wherein M, X, Y are as defined above and (dmf) is dimethylformamide, with a phosphine (P) selected among:

- phosphines of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic groups; and

- an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl;

and at least one nitrogen-containing compound NN selected among wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H. Compounds of formula MXY(CO)(PPh ₃ ) ₂ or of formula MXY(CO)(PPh ₃ ) ₂ (dmf) may be prepared by reacting compounds of formula MXY(PPh ₃ )k, wherein k is 2 or 3 with carbon monoxide, in the presence of a suitable organic solvent and optionally of dimethylformamide.

According to an embodiment, when X = Y = CI, the compound MCI ₂ (CO)(PPh ₃ ) ₂ (dmf) may be formed by reacting MCI ₂ (PPh ₃ ) ₃ with CO in the presence of dimethylformamide and a suitable organic solvent. When M is Ru, the compound RuCl ₂ (CO)(PPh ₃ ) ₂ (dmf) may be formed by reacting RuCl ₂ (PPh ₃ ) ₃ with CO in the presence of dimethylformamide and a suitable organic solvent.

According to an embodiment, when X = Y = acetate (OAc), the compound M(OAc) ₂ (CO)(PPh ₃ ) ₂ may be formed by reacting M(OAc) ₂ (PPh ₃ ) ₂ with CO in the presence of a suitable organic solvent. When M is Ru, the compound Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ may be formed by reacting Ru(OAc) ₂ (PPh ₃ ) ₂ with CO in the presence of a suitable organic solvent.

Compounds such as RuCl ₂ (PPh ₃ ) ₃ and Ru(OAc) ₂ (PPh ₃ ) ₂ are commercially available. According to a preferred embodiment, the present disclosure may refer to a process to obtain a complex of formula (VI) wherein M is Ru and X=Y= CI or acetate (OAc), by reacting RuCI ₂ (CO)(PPh ₃ ) ₂ (dmf) or Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ with a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic groups; and an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and {R)-{+)- 2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl;

and at least one nitrogen-containing compound NN selected among wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H.

According to a further embodiment, the present disclosure may refer to a process to obtain complexes of formula (VI) with the limitations described above.

Non limiting examples of referred com lexes of for

4 5 6 7

The synthesis of the monocarbonyl complexes 1 -3 involves the use of t,t,t- RuCl2(CO)(dmf)(PPh ₃ ) ₂ as starting product which can be prepared by reaction between the commercially available compound RuCI ₂ (PPh ₃ )3 with CO in dimethylformamide (dmf). The complex 1 was obtained by reacting RuCl2(CO)(dmf)(PPh ₃ ) ₂ with PCy ₃ via the mixed phosphine intermediate RuCI ₂ (CO)(dmf)(PPh ₃ )(PCy3) in CH ₂ CI ₂ and further addition of ethylenediamine, whereas reaction with 2-(aminomethyl)pyridine, in place of ethylenediamine, gave complex 2. Similarly, complex 3 was prepared using P/Pr ₃ , in place of PCy ₃ , with ethylenediamine. Similarly the complexes 4-7 of the invention were prepared from Ru(OAc) ₂ (CO)(PPh ₃ )2 as starting product, which can be easily prepared on gram-scale by reaction between Ru(OAc)2(PPh ₃ ) ₂ with CO in MeOH. The complexes 4 and 5 were obtained as a mixture by reacting Ru(OAc)2(CO)(PPh ₃ ) ₂ with the ligand ethylenediamine in CH2CI2, whereas reaction with 2-(aminomethyl)pyridine, in place of ethylenediamine, gave complexes 6 and 7 in a similar ratio of isomer (about 2/3, in favour of the c/s-OAc isomers).

The activity in transfer hydrogenation of complex 2 is higher than that of complexes known in the art, such as RuCI ₂ (CO)(ampy)(PPh ₃ ), reported by Cavarzan et al. {Polyhedron 2013, 62, 75), since the presence of the more basic phosphine allows the reduction at lower catalyst loading (S/C 5000 vs. 500).

According to an embodiment, the present disclosure may refer to a complex of formula (VII)

[MX(CO)(NN)(PP)]W (VII)

wherein M, X, W, (NN) and (PP) are as defined above and provided that when X is CI or H, (NN) is not ethylenediamine or 2-(aminomethyl)pyridine and the diphosphine (PP) is not Ph ₂ P(CH2CH ₂ CH2)PPh2.

According to a specific embodiment, the present disclosure may refer to complexes of formula (VII) wherein M, X, and (NN) are as defined above, provided that when X is CI or H, the diphosphine (PP) may be selected among:

- ferrocene optionally substituted with C1 -C20 aliphatic groups;

- an optically active diphosphine selected from the group consisting of (fl)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (A)-(1 ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], (R)-1 -{-2-[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, (ft)-1 -{-2-[bis(3,5-dimethyl-4- methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane.

The present disclosure also refers to a process to obtain complexes of formula (VII) comprising reacting [MXY(CO) ₂ ]n, MXY(CO)(PPh ₃ ) ₂ or MXY(CO)(PPh ₃ ) ₂ (dmf), wherein M, X and Y are as defined above and (dmf) is dimethylformamide, with a diphosphine (PP) selected among:

a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene, optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; and

an optically active diphosphine selected from the group consisting of (ft)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (fi)-(1 ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-( ¹ ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], (ft)-1 -{-2-

[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5- dimethyl-4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohe xyl phosphine and (2fl,4fl)-2,4-bis(diphenylphosphine)pentane;

and at least one nitrogen-containing compound NN selected among:

wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H.

According to a preferred embodiment, the present disclosure may refer to a process to obtain a complex of formula (VII) wherein M is Ru and X=Y= CI or acetate (OAc), by reacting [RuCI ₂ (CO) ₂ ] _n or RuCI ₂ (CO)(PPh ₃ )2(dmf) or Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ with a diphosphine (PP) selected among:

- a diphosphine of formula P(R ¹⁹ ) ₂ - Z -P(R ²⁰ ) ₂ , wherein Z is a C2-C4 aliphatic group or ferrocene, optionally substituted with C1 -C20 aliphatic groups, wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; and

an optically active diphosphine selected from the group consisting of (R)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (fi)-(1 ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-( ¹ ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], -{-2- [diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5- dimethyl-4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohe xyl phosphine and (2fl,4fl)-2,4-bis(diphenylphosphine)pentane;

and at least one nitrogen-containing compound NN selected among: wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H.

According to a further embodiment, the present disclosure may refer to a process to obtain complexes of formula (VII) with the limitations described above.

The synthetic route described above gives access to several diphosphine derivatives, including derivatives of achiral and chiral diphosphine ligands.

Non limiting examples of preferred complexes of formula (VII) are:

8

10 11

14 15 The cationic monocarbonyl derivatives 8 and 9 were obtained either from the polymer [RuCI ₂ (CO)2] _n , synthesized by reaction of RuCI ₃ -2.5H ₂ O with formic acid or from the complex RuCI ₂ (CO)(dmf)(PPh ₃ )2. Reaction of [RuCI ₂ (CO) ₂ ]n with 1 ,4- bis(diphenylphosphino) butane and ethylenediamine in 2-propanol led to 8, whereas using 1 ,1 '-bis(diphenylphosphino) ferrocene, in place of 1 ,4-bis(diphenylphosphino) butane, gave 9. Reaction of RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ takes place in CH ₂ CI ₂ and affords the same products.

The cationic monocarbonyl derivatives 10-15 were obtained from the complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ as starting product. The complex 10 was obtained by a one-pot reaction of Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ with the ligands 1 ,4-bis(diphenylphosphino)butane and ethylenediamine in CH ₂ CI ₂ . The complex 11 was obtained, in a similar manner, by using 2-(aminomethyl)pyridine in place of ethylenediamine. The complexes 12 and 13 were obtained using the ligand 1 ,1 '-bis(diphenylphosphino)ferrocene in place of 1 ,4- bis(diphenylphosphino)butane and the ligands ethylenediamine and 2- (aminomethyl)pyridine, respectively.

Similarly the complexes 14 and 15 were obtained from the diphosphine (fl)-1 -[(Sp)-2- (diphenylphosphino)ferrocenylethyl]diphenylphosphine and the ligands (1 fl,2fl)-1 ,2- diphenylethylenediamine and (1 S,2S)-1 ,2-diphenylethylenediamine.

The ligands of the type HCNN (lla-b) have the ability to act both as bidentate (lla-b) or tridentate ligands of the type (llc-d) when deprotonated.

According to an embodiment, in the case of bidentate ligand the coordination occurs through the nitrogen atom of the -NH ₂ group and a second nitrogen atom of the heterocycle, in combination with a monophosphine to the metal. Thus, the present disclosure may refer to a complex of formula (VIII)

MXY(CO)(HCNN)(P) (VIII)

wherein M, X, Y, (HCNN) and (P) are as defined above.

Preferably, the monodentate phosphine (P) is a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups.

The present disclosure also refers to a process to obtain complexes of formula (VIII) comprising reacting a compound of formula MXY(CO)(PPh ₃ ) ₂ , or of formula MXY(CO)(PPh ₃ ) ₂ (dmf), wherein M, X, Y are as defined above and (dmf) is dimethylformamide, with a nitrogen-containing compound HCNN selected among:

ί.ϋ* wherein

R ⁷ - R ¹³ are independently selected among H, C1 -C20 aliphatic groups, and C5-C20 aromatic groups, preferably R ⁸ -R ¹³ may be H and/or R ⁷ may be 4-methyl, and optionally with a phosphine (P) selected among:

- a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; and

- an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl.

According to a preferred embodiment, the present disclosure may refer to a process to obtain a complex of formula (VIII) wherein M is Ru and X=Y= CI or acetate (OAc) and P = PPh ₃ by reacting RuCI ₂ (CO)(PPh ₃ )2(dmf) or Ru(OAc) ₂ (CO)(PPh ₃ )2 with a nitrogen- containing compound HCNN selected among:

wherein

R ⁷ - R ¹³ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ⁸ -R ¹³ may be H and/or R ⁷ may be 4-methyl.

Examples of preferred complexes of formula (VIII) are:

The monocarbonyl phosphine derivatives 16-18 were isolated from RuCI ₂ (CO)(PPh ₃ )2(dmf) and 6-(4-methylphenyl)-2-(aminomethyl)pyridine, 2- (aminomethyl)benzo[/7]quinoline and 4-phenyl-2-(aminomethyl) benzo[/7]quinoline in CHCI3.

The neutral acetate monocarbonyl triphenylphosphine derivative 19 was obtained by reacting Ru(OAc) ₂ (CO)(PPh ₃ )2 and 6-(4-methylphenyl)-2-(aminomethyl)pyridine in toluene.

Known complexes such as RuCI ₂ (CO)(ampy)(PPh ₃ ) (Cavarzan et al., Polyhedron 2013, 62, 75) shows remarkably lower activity and require a higher catalyst loading compared to compound 16 in transfer hydrogenation. The presence of the aromatic ring in the 6 position or the presence of a benzoquinoline ring lead to catalysts with a remarkably higher activity with respect to those containing the simple 2-(aminomethyl)pyridine ligand on account of the cyclometalation which occurs in the catalysis.

The HCNN ligands of the type (lla), which contain a pyridine ring functionalized in the 6 position with an aromatic group, and those of the type (Mb), containing the benzo[/7]quinoline system, have the ability to act as anionic tridentate ligands (llc-d) through the nitrogen atom of the -NH ₂ group _, a second nitrogen atom of the heterocycle and a cyclometalated carbon atom with the metal. Thus, according to a further embodiment, the present disclosure may refer to complexes of formula (IX)

MX(CO)(CNN)(P) (IX)

wherein M, X, (CNN) and (P) are as defined above.

The present disclosure also refers to a process to obtain complexes of formula (IX) by (i) reacting a compound of formula MXY(PPh ₃ ) ₃ , wherein M, X and Y are as described above, with a nitrogen-containing ligand (CNN) of formula (lie) or (lid)

wherein

R ⁷ - R ¹³ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ⁸ -R ¹³ may be H and/or R ⁷ may be 4-methyl, and optionally a phosphine (P) selected among:

- a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; - an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and (R)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl, thereby obtaining an intermediate derivative and

(ii) reacting said derivative with CO.

According to a preferred embodiment, the present disclosure may refer to a process to obtain a complex of formula (IX) wherein M is Ru, X=Y= CI and P=PPh ₃ by reacting RuCI(CNN)(PPh ₃ ) ₂ with CO where CNN is a nitrogen-containing ligand CNN selected among

wherein

R ⁷ - R ¹³ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ⁸ -R ¹³ may be H and/or R ⁷ may be 4-methyl.

RuCI(CNN)(PPh ₃ ) ₂ can be prepared according to processes known in the art, for example as described in WO2009/007443.

Non limiting examples of preferred complexes of formula (IX) are:

20 21 22

The monocarbonyl complexes 20-22 were obtained from the diphosphine pincer precursors RuCI(CNN)(PPh ₃ ) ₂ (CNN = amtp, ambq and ambq ^Ph ) by reaction with CO in

The anionic bidentate ligands of the type (IVb), obtained by deprotonation of an ortho- methyl group, have the ability through P and C atoms, in combination with a NN ligand, to coordinate ruthenium or osmium. Therefore, according to an embodiment, the present disclosure may refer to the complex of formula (X)

MX(CO)(NN)(CP) (X) wherein M, X, (NN) and (CP) are as defined above, with the proviso that when X is CI, (NN) is not ethylenediamine or 2-(aminomethyl)pyridine and (CP) is not a compound of formula (IVb) in which R ²¹ = R ²² = phenyl and R ²³ = methyl.

According to an embodiment, R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, more preferably R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be independently selected among phenyl and cyclohexyl group. According to a further embodiment, the present disclosure may refer to a complex of formula (X) wherein M, X, (NN) and (CP) are as defined above, with the proviso that when X is CI, R ²¹ and R ²² are not aromatic groups.

According to a further embodiment, the present disclosure may refer to a complex of formula (X) in which M, X, (NN) are as defined above, (CP) is a ligand of formula (IVb)

wherein

pj2i _ pj23 _are j _nc | _e p _enc | _en tiy selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, more preferably R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be independently selected among phenyl and cyclohexyl group; with the proviso that when X is CI, R ²¹ and R ²² are not aromatic groups.

The present disclosure refers also to a process to obtain complexes of formula (X) comprising:

(i) reacting MX ₃ -xH ₂ O with a HCP compound of formula (IVa)

wherein

M and X are as defined above and R ²¹ - R ²³ are independently selected among H, C1 - C20 aliphatic groups and C5-C20 aromatic groups, thereby obtaining an intermediate complex of formula (XI); and (ii) reacting the complex of formula (XI) with a (NN) ligand of formula la to lc:

wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H.

According to a preferred embodiment, the present disclosure may refer to a process to obtain a complex of formula (X) wherein M is Ru and X is CI, comprising:

(i) reacting RuCl ₃ -xH ₂ O with a HCP compound of formula (IVa)

wherein

R ₅ 21 - r R.23 are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, thereby obtaining an intermediate complex of formula (XI); and (ii) reacting the complex of formula (XI) with a (NN) ligand of formula (la-lc):

¾ wherein

R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic group, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ may be H.

According to a further embodiment, the present disclosure may refer to a process to obtain complexes of formula (X) with the limitations described above.

Non limiting examples of preferred complexes of formula (X) are:

23 24

Complexes 23, 24 were synthesized from 25 by reaction with ethylenediamine or 2- (aminomethyl)pyridine, respectively, via displacement of the phosphine.

According to a further embodiment, the present disclosure may refer to a complex of formula (XI)

MX(CO)(CP)(HCP) (XI)

wherein M, X, (CP) and (HCP) are as defined above and with the proviso that when X is CI and R ²³ is -CH ₃ , R ²¹ and R ²² are not phenyl groups. According to an embodiment, R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, preferably R ²¹ - R ²² may be cyclohexyl groups.

According to a specific embodiment, the present disclosure may refer to complexes of formula (XI) wherein M, X, (CP) and (HCP) are as defined above, with the proviso that when X is CI, R ²¹ and R ²² are not an aromatic groups.

The complex of formula (XI) is a pentacoordinate complex.

The present disclosure also refers to a process to obtain complexes of formula (XI) comprising reacting MX ₃ -xH ₂ O with a HCP compound of formula (IVa)

wherein

M and X are as defined above and R - R are independently selected among H, C1 - C20 aliphatic groups and C5-C20 aromatic groups, R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, preferably R ²¹ - R ²² may be cyclohexyl groups.

According to a preferred embodiment, the present disclosure may refer to a process to obtain complexes of formula (XI) in which M is Ru and X is CI by reacting RuCI ₃ -xH ₂ O with a HCP compound of formula (IVa) wherein

pj2i _ pj23 _are j _nc | _e p _enc | _en tiy selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, preferably R ²¹ - R ²² may be cyclohexyl groups.

According to an embodiment, the present disclosure may refer to a process to prepare complexes of formula (XI) with the limitations described above.

Non limiting examples of preferred complexes of formula (XI) is:

25

The complexes of formula (XI) may be synthesized using the anionic bidentate ligands of the type (IVb), obtained by deprotonation of an ortho-methyl group, which have the ability through P and C atoms, to coordinate ruthenium and osmium.

The cyclometallated monocarbonyl derivatives 25 was prepared by reaction of RuCI ₃ -xH ₂ O with (2,6-dimethylphenyl)dicyclohexylphosphine in ethanol and the presence of formaldehyde and triethylamine.

According to an embodiment, the present disclosure may refer to complexes of formula

(XII)

MXY(CO)(PP)(P) (XII)

wherein M, X, Y, (PP) and (P) are as defined above. Preferably, (P) is triphenylphosphine.

The present disclosure also refers to a process to obtain the complexes of formula (XII) comprising reacting a compound of formula MXY(CO)(PPh ₃ ) ₂ , or of formula MXY(CO)(PPh ₃ ) ₂ (dmf), wherein M, X, Y are as defined above and (dmf) is dimethylformamide, with a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic groups;

- an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and

(fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl;

and a diphosphine (PP) selected among:

a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups;

- an optically active diphosphine selected from the group consisting of (ft)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (ft)-( ¹ ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], (R)-1 -{-2-[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, (fl)-1 -{-2-[bis(3,5-dimethyl-4- methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane.

According to a preferred embodiment, the present disclosure refers to a process to obtain a complex of formula (XII) in which M is Ru and X is CI or acetate group (OAc), by reacting RuCI ₂ (CO)(PPh ₃ )2(dmf) or Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ with a phosphine (P) selected among:

a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic group and C5-C20 aromatic groups;

- an optically active phosphine selected among (S)-neomenthyldiphenylphosphine and (ft)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '-binaphthyl;

and a diphosphine (PP) selected among:

a diphosphine of formula P(R ¹⁹ ) ₂ - Z -P(R ²⁰ ) ₂ , wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups;

an optically active diphosphine selected from the group consisting of (fl)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (ft)-( ¹ ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], (R)-1 -{-2-[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, (fl)-1 -{-2-[bis(3,5-dimethyl-4- methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane.

Non limitin examples of preferred complexes of formula (XII) are:

36

Complexes 26-36 have been synthesized by substitution of one or two triphenylphosphine from RuCI ₂ (CO)(PPh ₃ )2(dmf) or Ru(OAc) ₂ (CO)(PPh ₃ )2.

In a further embodiment, the present disclosure may refer to a complex of formula (XIII)

MXY(CO)(HCN)(PP) (XIII)

wherein M, X, Y, (HCN) and (PP) are as defined above.

Preferably, the diphosphine (PP) is selected among a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups.

The present disclosure also refers to a process to obtain a complex of formula (XIII) comprising reacting a compound of formula MXY(CO)(PPh ₃ ) ₂ , or of formula MXY(CO)(PPh ₃ )2(dmf), wherein M, X, Y are as defined above and (dmf) is dimethylformamide, with a diphosphine (PP) selected among:

- a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups;

- an optically active diphosphine selected from the group consisting of (fl)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (ft)-(1 ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (ft)-(1 Λ '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], -{-2-[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, (fl)-1 -{-2-[bis(3,5-dimethyl-4- methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane;

and a nitrogen-containing ligand (HCN) of formula Ilia

wherein

R ¹⁴ and R ¹⁵ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ¹⁴ and R ¹⁵ may be independently H.

According to a specific embodiment, the present disclosure refers to a process to obtain a complex of formula (XIII) in which M is Ru and X is CI or acetate group, by reacting a compound of formula RuCI ₂ (CO)(PPh ₃ )2(dmf) or Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ with a phosphine (PP) selected among:

a diphosphine of formula P(R ¹⁹ ) ₂ - Z -P(R ²⁰ ) ₂ , wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups;

an optically active diphosphine selected from the group consisting of (fl)-(6,6'- dimethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine], (fi)-(1 ,1 '-binaphthalene-2,2'- diyl)bis(diphenylphosphine), (fl)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5- dimethylmethyl)phosphine], (fl)-1 -{-2- [diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5- dimethyl-4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohe xyl phosphine and (2ft,4ft)-2,4-bis(diphenylphosphine)pentane;

and a nitrogen-containing ligand (HCN) of formula Ilia

wherein

R ¹ - R ¹⁵ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ¹⁴ and R ¹⁵ may be independently H.

Non limiting examples of preferred complexes of formula (XIII) are:

In a further embodiment, the present disclosure may refer to a complex of formula (XIV)

MXY(CO)(PNN) (XIV)

wherein M, X, Y and (PNN) are as defined above.

According to a specific embodiment, the present disclosure may refer to complexes of formula (XIV) wherein M, X, Y and (PNN) are as defined above, provided that when X = Y, X and Y are not CI.

The present disclosure also refers to a method to obtain the complexes of formula (XIV) comprising reacting a compound of formula MXY(CO)(PPh ₃ ) ₂ , or of formula MXY(CO)(PPh ₃ ) ₂ (dmf), wherein M, X, Y are as defined above and (dmf) is dimethylformamide with a tridentate (PNN) ligand of formula (V)

wherein

R - R are independently selected among H, C1 -C20 alkyl group and C5-C20 aryl groups, preferably R ²⁴ and R ²⁷ -R ²⁹ may be H and/or R ²⁵ and R ²⁶ may be a C1 -C20 aromatic group, more preferably a phenyl group.

According to a specific embodiment, the present disclosure may refer to a process to obtain a complex of formula (XIV) in which M is Ru and X is acetate group comprising reacting a compound of formula Ru(OAc) ₂ (CO)(PPh ₃ )2 with a tridentate (PNN) ligand of formula (V)

wherein

R ²⁴ - R ²⁹ are independently selected among H, C1 -C20 alkyl groups and C5-C20 aryl groups, preferably R ²⁴ and R ²⁷ -R ²⁹ may be H and/or R ²⁵ and R ²⁶ may be a C1 -C20 aromatic group, more preferably a phenyl group.

According to a further embodiment, the present disclosure may refer to a process to obtain a complex of formula (XIV) with the limitations described above.

A non-limiting example of complexes of formula (XIV) is:

39

Complexes of formula (1 ) and sub-formulas (VI-XIV) have been found to be highly active in transfer hydrogenation of ketones and aldehydes and can be used in hydrogenation of the same compounds using molecular hydrogen.

A further aspect of the present disclosure is the use of the complex of formula (1 ) or of sub-formulas (VI-XIV) as catalysts or pre-catalyst for the reduction reaction of ketones or aldehydes to alcohols by transfer hydrogenation or hydrogenation with molecular hydrogen.

In another aspect, the present disclosure refers to a process for the reduction of ketones or aldehydes to the corresponding alcohols comprising the following steps:

(a) mixing a catalyst or pre-catalyst with a solution comprising at least one base and at least one substrate selected from the group consisting of C3-C42 ketones and C2-C41 aldehydes thereby obtaining a mixture; and

(b) contacting said mixture with molecular H ₂ or with at least one hydrogen-donor, preferably 2-propanol, sodium formate, ammonium formate, a mixture of formic acid and triethylamine,

said process being characterized in that the catalyst or pre-catalyst is a pentacoordinate or a hexacoordinate complex of general formula (1 ):

[MXY _a (CO)L _b L' _c ]Wd (1 )

wherein

M = Ru or Os;

a, b and d are independently 0 or 1 ;

c is 1 or 2;

X, Y are independently selected among halides, hydride, C1 -C20 carboxylates and C1 - C20 alkoxides;

W is selected among halides, C1 -C20 carboxylates and C1 -C20 alkoxides;

L is a nitrogen-containing ligand selected among:

(I) a NN compound of formula la to lc:

a HCNN compound of formula lla - Mb and a CNN ligand of formula lie

ilia} iikii

(III) a HCN compound of formula Ilia

wherein

R ¹ - R ¹⁵ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ¹ and R ² may be independently selected among H and a phenyl group and/or R ³ -R ⁶ and R ⁸ -R ¹⁵ may be H and/or R ⁷ may be 4-methyl;

L' is at least one phosphorus-containing ligand selected among:

- a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active phosphine selected among (S)- neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '- binaphthyl;

- a diphosphine (PP) selected among: a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active diphosphine selected from the group consisting of (fl)-(6,6'-dimethoxybiphenyl-2,2'- diyl)bis(diphenylphosphine], (fi)-(1 ,1 '-binaphthalene-2,2'-diyl)bis(diphenylphosphine), (H)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5-dimethylmethyl)phosphi ne], (fl)-1 -{-2- [diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5-dimethyl- 4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane;

- a HCP compound of formula (IVa) and a CP ligand of formula (IVb) wherein

pj2i _ pj23 _are j _nc | _e p _enc | _en tiy selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, preferably R ²¹ - R ²² may be cyclohexyl groups;

- a PNN compound of formula (V)

wherein

R - R are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ²⁴ and R ²⁷ -R ²⁹ may be H and/or R ²⁵ and R ²⁶ may be a C1 - C20 aromatic group, more preferably a phenyl group.

According to a further embodiment, the present disclosure may refer to a process for the reduction of ketones or aldehydes to the corresponding alcohols, wherein the catalyst or pre-catalyst is a pentacoordinate or a hexacoordinate complex of general formula (1 ) with at least one of the limitations described above.

The complex of formula (1 ) containing only phosphorus-containing ligands L' is conveniently used as pre-catalyst in transfer hydrogenation or hydrogenation with molecular hydrogen, wherein the (transfer)hydrogenation is carried out in the presence of a nitrogen-containing ligand L.

Therefore, according to an embodiment, the present disclosure refers to a process for the reduction of ketones or aldehydes to the corresponding alcohols, comprising the following steps:

(a) mixing a pre-catalyst with a solution comprising at least one base and at least one substrate selected from the group consisting of C3-C42 ketones and C2-C41 aldehydes thereby obtaining a mixture; and (b) contacting said mixture with molecular H ₂ or with at least one hydrogen-donor, preferably 2-propanol, sodium formate, ammonium formate, a mixture of formic acid and triethylamine,

wherein said pre-catalyst has general formula (2):

[MXY _a (CO)L'c]Wd (2)

wherein

M = Ru or Os;

a, b and d are independently 0 or 1 ;

c is 1 or 2;

X, Y are independently selected among halides, hydride, C1 -C20 carboxylates and C1 - C20 alkoxides;

W is selected among halides, C1 -C20 carboxylates and C1 -C20 alkoxides;

L' is at least one phosphorus-containing ligand selected among:

- a phosphine (P) selected among: a phosphine of formula PR ¹⁶ R ¹⁷ R ¹⁸ , wherein R ¹⁶ - R ¹⁸ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active phosphine selected among (S)- neomenthyldiphenylphosphine and (fl)-(+)-2-(diphenylphosphino)-2'-methoxy-1 ,1 '- binaphthyl;

- a diphosphine (PP) selected among: a diphosphine of formula P(R ¹⁹ )2 - Z -P(R ²⁰ )2, wherein Z is a C2-C4 aliphatic group or ferrocene optionally substituted with C1 -C20 aliphatic groups, and wherein R ¹⁹ and R ²⁰ are independently selected among C1 -C20 aliphatic groups and C5-C20 aromatic groups; an optically active diphosphine selected from the group consisting of (fl)-(6,6'-dimethoxybiphenyl-2,2'- diyl)bis(diphenylphosphine], (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis(diphenylphosphine), (ft)-(1 ,1 '-binaphthalene-2,2'-diyl)bis[bis(3,5-dimethylmethyl)phosphi ne], (ft)-1 -{-2-

[diphenylphosphine]ferrocenyl}ethyldicyclohexyl phosphine, -{-2-[bis(3,5-dimethyl- 4-methoxyphenyl)phosphine]ferrocenyl}ethyldicyclohexyl phosphine and (2fl,4fl)-2,4- bis(diphenylphosphine)pentane;

- a HCP compound of formula (IVa) and a CP ligand of formula (IVb)

wherein

R ²¹ - R ²³ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups R ²³ may be -CH ₃ and/or R ²¹ - R ²² may be C6-C20 cycloaliphatic group or C6-C20 aromatic group, preferably R ²¹ - R ²² may be cyclohexyl groups

and wherein

step (a) is carried out by mixing said pre-catalyst with a solution further comprising at least one nitrogen-containing compound L selected among:

(i) a NN compound of formula la to lc:

(ii) a HCNN compound of formula I la. - Mb and a CNN ligand of formula lie - lid:

{li ; (Mi

(iii) a HCN compound of formula Ilia

(iv) a PNN compound of formula (V)

wherein

R ¹ - R ¹⁵ and R ²⁴ - R ²⁹ are independently selected among H, C1 -C20 aliphatic groups and C5-C20 aromatic groups, preferably R ¹ and R ² and R ²⁴ - R ²⁹ may be independently selected among H and a phenyl group and/or R ³ -R ⁶ and R ⁸ -R ¹⁵ may be H and/or R ⁷ may be 4-methyl.

Preferably, the nitrogen-containing compound is selected among NN compounds of formula (la) to (lc)

wherein R ¹ - R ⁶ are independently selected among H, C1 -C20 aliphatic groups and C5- C20 aromatic groups. More preferably, the nitrogen-containing compound is selected among ethylenediamine and 2-(aminomethyl)pyridine.

According to an embodiment, the step (a) of the processes described above may be conducted in the presence of a base, wherein said base may be potassium hydroxide, potassium carbonate or an alkali metal alkoxide preferably selected among sodium iso- propoxide, potassium tert-butoxide, more preferably is potassium tert-butoxide, and in step (b) the mixture is contacted with molecular hydrogen.

According to a further embodiment, in the process of the disclosure in step (a) the base is sodium iso-propoxide and in step (b) the mixture is contacted with at least one hydrogen donor.

The transfer hydrogenation reduction process of the present disclosure may be carried out at a temperature of 30 - 82 °C.

In one embodiment, the reduction reactions by hydrogenation may be carried out at 40- 70 ^Q C under hydrogen atmosphere (5-30 atm) in presence of methanol or ethanol as solvent. Under these reaction conditions the conversion of the ketone or aldehyde to alcohol is good to complete. The complex of the present disclosure can be used for the preparation of alcohols, also chiral, by the reduction of C3-C41 ketones and of C2-C41 aldehydes.

In the process of the disclosure, the substrate may be:

- at least one C3-C41 ketone selected among compounds of formula R ³⁰ C(=O)R ³¹ wherein R ³⁰ and R ³¹ are independently selected among C1 -C20 aliphatic, substituted aliphatic, aromatic, substituted aromatic and heteroaromatic groups wherein optionally R ³⁰ and R ³¹ are linked to form a cycle;

- at least one C2-C41 aldehyde is selected among compounds of formula R ³² C(=O)H, wherein R ³² is selected among C1 -C40 aliphatic, substituted aliphatic, aromatic, substituted aromatic and heteroaromatic groups; and

- mixtures thereof.

According to an embodiment, in the process of the present disclosure the molar ratio substrate/catalyst or pre-catalyst may range from 1000/1 to 100000/1 , preferably from 1000/1 to 50000/1 .

According to a further embodiment, in the process of the present disclosure the molar ratio substrate/base may range from 10/1 to 100/1 .

In a further embodiment, the present disclosure may refer to complexes of formula (1 ) and (2) and of sub-formulas (VI)-(XIV) as described above in which M is Ru.

In a further embodiment, the present disclosure may refer to complexes of formula (1 ) and (2) and of sub-formulas (VI-XIV) as described above, wherein X and Y are equal. More preferably, the present disclosure may refer to complexes of formula (1 ) and (2) and of sub-formulas (VI-XIV) as described above, wherein X and Y are equal and are selected among CI and acetate group.

In a further embodiment, the present disclosure may refer to a complex of formula (1 ) and (2) and of sub-formula (VII) as described above, wherein W is chlorine.

These and other objects as well as features and advantages of the present invention will be better understood from the following detailed description and from the preferred embodiments which are given for illustrative purposes and not limitative of the invention itself.

Example 1 : Synthesis of the complex RuCI ₂ (CO)(en)(PCy ₃ ) (1)

The complex RuCl2(CO)(dmf)(PPh ₃ ) ₂ (250 mg, 0.31 mmol, 1 equiv), suspended in 5 mL of dichloromethane, was reacted with PCy3 (176 mg, 0.63 mmol, 2 equiv). After stirring the mixture for 3 hours at room temperature, the ligand en (25 μΙ_, 0.37 mmol, 1 .2 equiv) was added and the solution was stirred for 3 hours at room temperature. The volume was reduced to about half and the complex was precipitated by adding 5 mL of pentane. The obtained solid was filtered, washed 2 times with 10 mL of ethyl ether and dried under reduced pressure. Yield: 149 mg (89%). Anal. Calcd (%) for C ₂ i H ₄ iCI ₂ N ₂ OPRu: C, 46.66; H, 7.65; N, 5.18, Found: C, 46.39; H, 7.49; N, 5,36. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 3.77 - 3.62 (m, 2H), 3.35 - 3.20 (m, 2H), 3.09 (dd, J = 10.9, 5.5 Hz, 2H), 2.92 (dd, J = 9.7, 6.0 Hz, 2H), 2.32 - 1 .08 (m, 33H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 206.0 (d, J = 16.8 Hz), 43.5 (d, J = 2.8 Hz), 42.3 (d, J = 1 .5 Hz), 35.3 (d, J = 21 .0 Hz), 29.7, 28.2 (d, J = 10.0 Hz), 27.0. ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 45.5. IR (cm ^"1 ): 1936.

Example 2: Synthesis of the complex RuCI ₂ (CO)(ampy)(PCy ₃ ) (2)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ (300 mg, 0.38 mmol, 1 equiv), suspended in 5 mL of dichloromethane, was reacted with the ligand PCy ₃ (210 mg, 0.75 mmol, 2 equiv). After stirring the mixture for 3 hours at room temperature, the ligand ampy (47 μΐ, 0.45 mmol, 1 .2 equiv) was added. The solution was stirred for 3 hours at room temperature, the volume was reduced to about half and the complex was precipitated by adding 5 mL of pentane. The obtained solid was filtered, washed 2 times with 10 mL of ethyl ether and dried under reduced pressure. Yield: 187 mg (84%). Anal. Calcd (%) for C ₂₅ H ₄₁ CI ₂ OPRu: C, 51 .02; H, 7.02; N, 4.76, Found: C, 51 .26; H, 7.22; N, 4.57. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 9.1 1 (d, J = 5.5 Hz, 1 H), 7.88 - 7.62 (m, 1 H), 7.55 - 7.28 (m, 1 H), 7.28 - 7.10 (m, 1 H), 4.70 (t, J = 5.9 Hz, 2H), 4.20 (t, J = 5.6 Hz, 2H), 2.33 (ddt, J = 23.4, 12.1 , 2,8 Hz, 3H), 2.18 - 1 .06 (m, 30H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 207.5 (d, J = 17.8 Hz), 160.1 , 152.55, 137.6, 124.4 (d, J = 2.2 Hz), 1 21 .7 (d, J = 2.0 Hz), 50.6 (d, J = 2.3 Hz), 34.5 (d, J = 21 .1 Hz), 29.5, 28.1 (d, J = 10.1 Hz), 27.0. ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 45.9. IR (cm ^"1 ): 1941 .

Example 3: Synthesis of the complex RuCI ₂ (CO)(en)(PiPr ₃ ) (3)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ (81 .7 mg, 0.10 mmol, 1 equiv), suspended in 5 mL of distilled dichloromethane, was reacted with the ligand P/Pr ₃ (25 μΐ, 0.13 mmol, 1 .3 equiv). After stirring the mixture for 3 hours at room temperature, the ligand en (1 1 μΐ, 0.16 mmol, 1 .6 equiv) was added. The solution was stirred for 3 hours at room temperature. The volume was reduced to about half and the complex was precipitated by adding 5 mL of pentane. The obtained solid was filtered, washed 2 times with 10 mL of ethyl ether and dried at reduced pressure. Yield: 28 mg (66%). Anal. Calcd (%) for Ci ₂ H ₂₉ CI ₂ N ₂ OPRu: C, 34.29; H, 6.95; N, 6.66, Found: C, 34.00; H, 7.20; N, 6.60. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 3.70 - 3.51 (m, 2H), 3.39 - 3.23 (m, 2H), 3.09 (dd, J = 1 1 .2, 5.7 Hz, 2H), 3.01 - 2.85 (m, 2H), 2.63 - 2.39 (m, 3H), 1 .33 (dd, J = 13.1 , 7.3 Hz, 18H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 205.8 (d, J = 17.0 Hz), 43.5 (d, J = 2.9 Hz), 42.2 (d, J = 1 .7 Hz), 25.1 (d, J = 22.4 Hz), 19.6 (d, J = 0.7 Hz). ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 55.8. IR (cm ^"1 ): 1921 .

Example 4: Synthesis of the complex Ru(OAc) ₂ (CO)(en)(PPh ₃ ) (4 and 5)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (150 mg, 0.19 mmol, 1 equiv) suspended in CH ₂ CI ₂ (2 mL) was reacted with the ligand en (16 μΐ, 0.24 mmol, 1 .2 equiv). After stirring the mixture for 2 h at room temperature, the volume was reduced to about half and the complex was precipitated by adding 10 mL of n-heptane. The obtained solid was filtered, washed 3 times with ethyl ether (3 mL), once with n-pentane (3 mL) and dried under reduced pressure. Yield: 64 mg (58%) as a mixture of cis and trans complexes 4 and 5, in 2/3 ratio respectively. Anal. Calcd (%) for C ₂₅ H ₂₉ N ₂ O ₅ PRu: C, 52.72; H, 5.13; N, 4.92, Found: C, 52.90; H, 5.02; N, 5.14. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 7.92 - 7.20 (m, 21 H), 7.06 - 6.84 (m, 0.4H), 5.28 - 5.13 (m, 0.4H), 5.04 - 4.85 (m, 2H), 4.01 - 3.78 (m, 2H), 3.23 - 3.04 (m, 0.4H), 2.88 - 2.75 (m, 0.4H), 2.75 - 2.57 (m, 2.8H), 2.54 - 2.37 (m, 2.8H), 1 .98 (s, 1 .2H), 1 .62 (s, 6H), 1 .58 (s, 1 .2H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 205.1 (d, J = 17.9 Hz), 204.7 (d, J = 17.9 Hz), 181 .6, 180.4, 179.4, 134.4 (d, J = 1 .3 Hz), 134.0 (d, J = 10.4 Hz), 133.8 (d, J = 10.5 Hz), 133.5 (d, J = 1 .3 Hz), 133.2 (d, J = 1 .0 Hz), 130.3, 130.3, 128.8 (d, J = 3.8 Hz), 128.6 (d, J = 3.7 Hz), 46.8 (d, J = 3.1 Hz), 44.5 (d, J = 2.4 Hz), 44.0 (d, J = 1 .9 Hz), 43.4 (d, J = 4.1 Hz), 25.3, 24.4, 24.3. ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 51 .6, 47.3. IR (cm ^"1 ): 1934, 1924.

Example 5: Synthesis of the complex Ru(OAc) ₂ (CO)(ampy)(PPh ₃ ) (6 and 7)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (150 mg, 0.19 mmol, 1 equiv) suspended in CH ₂ CI ₂ (2 mL) was reacted with the ligand Ampy (25 μΐ, 0.24 mmol, 1 .2 equiv). After stirring the mixture for 2 h at room temperature, the volume was reduced to about half and the complex was precipitated by adding 10 mL of n-heptane. The obtained solid was filtered, washed 3 times with ethyl ether (3 mL), once with n-pentane (3 mL) and dried under reduced pressure. Yield: 77 mg (64%) as a mixture of 6 and 7 in a 2/3 ratio respectively. Anal. Calcd (%) for C ₂₉ H ₂₉ N ₂ O ₅ PRu: C, 56.40; H, 4.73; N, 4.54, Found: C, 56.75; H, 4.59; N, 4.23. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 9.49 - 9.42 (m, 0.7H), 9.10 - 8.66 (m, 0.7H), 8.59 - 8.48 (m, 1 H), 7.83 - 7.22 (m, 25H), 5.40 (t, J = 5.7 Hz, 1 .4H), 4.21 (t, J = 6.2 Hz, 1 .4), 4.08 (dd, J = 16.2, 5.0 Hz, 1 H), 3.87 (ddd, J = 15.7, 9.8, 5.8 Hz, 1 H), 2.08 (s, 2.1 H), 2.01 (s, 2.1 H), 1 .43 (s, 3H), 1 .33 (s, 3H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 205.8 (d, J = 17.7 Hz), 205.5 (d, J = 18.9 Hz), 182.1 , 179.8, 177.8, 163.4, 161 .3 (d, J = 1 .8 Hz), 154.7, 150.3, 138.5, 138.0, 134.2 (d, J = 10.5 Hz), 134.1 (d, J = 10.5 Hz), 133.4, 133.0, 132.5, 130.5 (d, J = 2.3 Hz), 130.4 (d, J = 2.5 Hz), 128.8 (d, J = 9.8 Hz), 128.6 (d, J = 9.8 Hz), 124.2 (d, J = 2.8 Hz), 123.6 (d, J = 2.4 Hz), 121 .2 (d, J = 1 .8 Hz), 121 .0 (d, J = 1 .4 Hz), 52.9 (d, J = 2.3 Hz), 49.5 (d, J = 3.5 Hz), 25.0, 24.3, 24.1 . ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 53.8, 49.8. IR (cm ^"1 ): 1945, 1923.

Example 6: Synthesis of the complex [RuCI(CO)(en)(dppb)]CI (8)

The complex [RuCI ₂ (CO)2] _n (50 mg, 0.22 mmol, 1 equiv) suspended in 5 mL of distilled isopropanol, was reacted with the ligand dppb (94 mg, 0.22 mmol, 1 equiv). After stirring the mixture for 2 hours at 90 °C, the ligand en (15 μΐ, 0.22 mmol, 1 equiv) was added and stirred for further 2 hours at 90 °C. The solution was evaporated in vacuum, and the solid was dissolved in CHCI ₃ (3 mL) and stirred for 3 hours at room temperature. The volume was reduced by half, the complex was precipitated by adding 5 mL of pentane. The obtained solid was filtered, washed 2 times with 10 mL of ethyl ether and dried at reduced pressure.Yield: 151 mg (98%). Anal. Calcd (%) for C32H36CIN2O2P2RU: C, 56.60; H, 5.34; N, 4.13, Found: C, 56.59; H, 5.39; N, 4.20. ¹ H NMR (200 MHz, CDCI ₃ ) δ 7.84 - 7.65 (m, 4H), 7.56 - 7.29 (m, 16H), 3.68 - 3.37 (m, 2H), 3.05 - 2.74 (m, 4H), 2.65 - 2.35 (m, 4H), 2.18 - 1 .87 (m, 2H), 1 .76 - 1 .52 (m, 4H). ¹³ C NMR (50 MHz, CD2CI2) δ 199.5 (t, J = 13.6 Hz), 137.1 (t, J = 13.8 Hz), 135.9 (t, J = 13.9 Hz), 134.6 (t, J = 5.1 Hz), 131 .6 (d, J = 3.6 Hz), 130.4, 129.3 (t, J = 4.6 Hz), 129.0 (t, J = 5.0 Hz), 45.9, 25.5 (t, J = 13.8 Hz), 24.9 (t, J = 16.2 Hz), 22.1 . ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 37.4. IR (cm ^"1 ): 1969.

Example 7: Synthesis of the complex [RuCI(CO)(en)(dppf)]CI (9)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ )2 (200 mg, 0.25 mmol, 1 equiv) dissolved in CH ₂ CI ₂ (2 mL) was reacted with the ligand dppf (160 mg, 0.29 mmol, 1 .2 equiv) at room temperature for 2 h. The ligand en (15 μΐ, 0.37 mmol, 1 .5 equiv) was then added and the mixture was stirred at room temperature for 2 h. The solution was concentrated to about 0.5 mL and the complex was precipitated by addition of n-heptane (10 mL). The obtained solid was filtered and thoroughly washed 4 times with ethyl ether (3 mL) and dried under reduced pressure. Yield: 180 mg (88%). Anal. Calcd (%) for C ₃₇ H ₃ 6CI ₂ FeN ₂ OP ₂ Ru: C, 54.56; H, 4.46; N, 3.44, Found: C, 54.50; H, 4.51 ; N, 3.47. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 7.97 - 7.24 (m, 20H), 5.59 (s, 2H), 5.15 - 4.91 (m, 2H), 4.53 (s, 2H), 4.20 (s, 2H), 3.97 (s, 2H), 3.68 - 3.42 (m, 2H), 2.58 - 2.41 (m, 2H), 2.14 - 1 .85 (m, 2H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 204.0 (t, J = 14.8 Hz), 135.9 (t, J = 5.7 Hz), 134.2, 134.1 (d, J = 10.1 Hz), 133.4, 132.9 (t, J = 4.7 Hz), 132.0, 130.7, 130.4 (d, J = 2.4 Hz), 129.2 - 128.3 (m), 77.8 (t, J = 4.9 Hz), 75.7 (t, J = 3.2 Hz), 73.5 (t, J = 3.3 Hz), 71 .3 (t, J = 3.0 Hz), 45.7. ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 39.8. IR (cm ^"1 ): 1960.

Example 8: Synthesis of the complex [Ru(OAc)(CO)(en)(dppb)]OAc (10)

The complex Ru(OAc) ₂ (CO)(PPh ₃ )2 (200 mg, 0.26 mmol, 1 equiv) suspended in CH ₂ CI ₂ (2 mL) was reacted with the ligand dppb (120 mg, 0.29 mmol, 1 .1 equiv) at room temperature for 6 h. The ligand en (25 μΙ_, 0.37 mmol, 1 .4 equiv) was added and the solution was stirred at room temperature for further 2 h. The solution was concentrated to about 0.5 mL and the complex was precipitated by addition of n-heptane (10 mL). The obtained solid was filtered and washed 4 times with ethyl ether (3 mL) and dried under reduced pressure. Yield: 182 mg (97%). Anal. Calcd (%) for C ₃ 5H ₄₂ N ₂ O ₅ P ₂ Ru: C, 57.29; H, 5.77; N, 3.82 Found: C, 57.70; H, 5.90; N, 3.50. ¹ H NMR (200 MHz, CD ₃ OD) δ 7.64 - 7.30 (m, 21 H), 4.76 - 4.62 (m, 1 H), 4.30 - 4.14 (m, 1 H), 4.10 - 3.92 (m, 1 H), 2.92 - 2.47 (m, 6H), 1 .86 (s, 3H), 1 .58 (s, 3H), 1 .31 - 1 .18 (m, 2H). ¹³ C NMR (50 MHz, CD ₃ OD) δ 203.8 (t, J = 17.7 Hz), 182.7, 182.5, 134.8 (d, J = 10.5 Hz), 134.4 - 134.1 (m), 133.8 - 133.6 (m), 132.3, 131 .7, 131 .2 (d, J = 2.3 Hz), 130.1 (t, J = 4.8 Hz), 129.8 (t, J = 4.8 Hz), 129.4 (d, J = 9.7 Hz), 46.6 (d, J = 10.6 Hz), 44.7 (d, J = 1 1 .0 Hz), 30.1 (d, J = 6.7 Hz), 29.6 (d, J = 14.2 Hz), 25.5, 24.0, 23.5 . ³¹ P NMR (81 .0 MHz, CD ₃ OD) δ 37.1 . IR (cm ^"1 ): 1939.

Example 9: Synthesis of the complex [Ru(OAc)(CO)(ampy)(dppb)]OAc (11)

In an NMR tube the complex Ru(OAc) ₂ (CO)(dppb) (32) (31 mg, 0.05 mmol, 1 equiv) suspended in 0.6 mL of toluene-d ₈ , was reacted with the ligand ampy (5 μΐ, 0.05 mmol, 1 equiv). After stirring the mixture at room temperature for 30 min, the sample was characterized by NMR. The sample was then dried under low pressure. Yield: 31 .3 mg (87%). Anal. Calcd (%) for C ₃ 9H ₄₂ N ₂ O ₅ P ₂ Ru: C, 59.92; H, 5.42; N, 3.58 Found: C, 60.30; H, 5.60; N, 3.20. ¹ H NMR (200 MHz, toluene-d ₈ ) δ 8.19 - 7.94 (m, 4H), 7.61 - 6.80 (m, 17H), 6.68 - 6.55 (m, 1 H), 6.47 (dd, J = 7.0, 5.1 Hz, 1 H), 6.33 - 6.06 (m, 1 H), 4.20 (t, J = 17.4 Hz, 1 H), 3.20 (t, J = 12.0 Hz, 1 H), 3.07 - 2.86 (m, 1 H), 2.66 - 2.42 (m, 1 H), 2.03 (s, 3H), 1 .93 (s, 3H), 1 .84 - 1 .56 (m, 3H), 1 .48 - 1 .12 (m, 5H). ¹³ C NMR (50 MHz, toluene-ds) δ 203.3, 187.6, 177.0, 163.2, 159.8, 149.1 (d, J = 22.9 Hz), 135.6, 134.9 - 132.0 (m), 130.5 - 129.4 (m), 121 .3 (d, J = 13.4 Hz), 121 .3, 120.8, 50.4, 30.7, 30.1 , 29.9, 29.4, 25.8, 24.6 (d, J = 4.2 Hz). ³¹ P NMR (81 .0 MHz, toluene-d ₈ ) δ 46.4 (d, J = 28.8 Hz), 34.0 (d, J = 29.0 Hz). IR (cm ¹ ): 1944, 1608, 1586.

Example 10: Synthesis of the complex [Ru(OAc)(CO)(en)(dppf)]OAc (12) In an NMR tube the complex Ru(OAc) ₂ (CO)(dppf) (33) (31 .9 mg, 0.04 mmol, 1 equiv) suspended in 0.6 imL of toluene-d ₈ , was reacted with the ligand en (3 μΙ_, 0.05 mmol, 1 .1 equiv). After heating the mixture at 90 °C for 3 h, the sample was dried. The residue was dissolved in CD2CI2 and characterized by NMR. The sample was then dried under low pressure. Yield: 30.3 mg (88%). Anal. Calcd (%) for C ₄ i H ₄₂ FeN ₂ O ₅ P2Ru: C, 57.15;

H, 4.91 ; N, 3.25 Found: C, 57.10; H, 4.50; N, 2.91 . ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 7.94 - 7.20 (m, 20H), 4.67 - 4.04 (m, 8H), 3.08 - 2.46 (m, 8H), 1 .78 (s broad, 6H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 203.18 (t, J = 15.1 Hz), 181 .34 (s), 176.62 (dd, J = 12.1 , 5.5 Hz), 134.53 (t, J = 5.2 Hz), 134.01 (t, J = 5.3 Hz), 132.99 (dd, J = 16.2, 13.5 Hz), 131 .31 (s), 129.15 (t, J = 4.9 Hz), 128.57 (t, J = 4.9 Hz), 79.63 (dd, J = 65.8, 9.6 Hz), 75.90 (t, J = 4.2 Hz), 75.53 (t, J = 4.5 Hz), 73.09 (t, J = 3.1 Hz), 72.80 (t, J = 3.1 Hz), 45.70 (s), 26.06 (s). ³¹ P NMR (81 .0 MHz, CD ₂ CI ₂ ) δ 40.1 . IR (cm ^"1 ): 1963, 1617, 1569.

Example 1 1 : Synthesis of the complex [Ru(OAc)(CO)(ampy)(dppf)]OAc (13)

In an NMR tube the complex Ru(OAc) ₂ (CO)(dppf) (33) (30.4 mg, 0.04 mmol, 1 equiv) suspended in 0.6 imL of toluene-d ₈ , was reacted with the ligand ampy (4 μΙ_, 0.04 mmol, 1 equiv). After stirring at room temperature for 2 h, the sample was characterized by NMR. The sample was then dried under low pressure. Yield: 30.1 mg (87%). Anal. Calcd (%) for C ₄₅ H ₄₂ FeN ₂ O ₅ P ₂ Ru: C, 59.41 ; H, 4.65; N, 3.08 Found: C, 59.10; H, 4.40; N, 2.70. ¹ H NMR (200 MHz, toluene-d ₈ ) δ 8.68 (t, J = 8.5 Hz, 2H), 8.25 - 8.10 (m, 2H), 7.99 (t, J = 8.1 Hz, 2H), 7.75 (t, J = 8.5 Hz, 2H), 7.40 - 7.24 (m, 2H), 7.16 - 6.83 (m, 15H), 6.64 - 6.43 (m, 3H), 6.15 - 5.92 (m, 1 H), 5.80 (s, 1 H), 4.71 (s, 1 H), 4.21 (s, 1 H), 3.91 (s, 1 H), 3.72 (s, 1 H), 3.48 (s, 1 H), 2.54 (t, J = 14.6 Hz, 1 H), 2.41 - 2.25 (m, 1 H),

I .84 (s, 3H), 1 .66 (s, 3H). ¹³ C NMR (50 MHz, toluene-d ₈ ) δ 210.1 (d, J = 17.6 Hz), 178.3, 177.0 (d, J = 2.8 Hz), 160.1 (d, J = 3.9 Hz), 149.1 , 136.0 (d, J = 1 1 .8 Hz), 135.5, 134.5 (d, J = 10.7 Hz), 133.2 (d, J = 9.9 Hz), 130.9, 130.0 (d, J = 17.4 Hz), 128.3, 127.3, 121 .3 (d, J = 15.4 Hz), 77.0 (d, J = 3.8 Hz), 76.5 (d, J = 7.1 Hz), 75.3 (d, J = 7.3 Hz), 75.0 (d, J = 5.4 Hz), 74.8, 71 .3 (d, J = 5.3 Hz), 71 .1 (d, J = 3.5 Hz), 70.3 (d, J = 5.8 Hz), 50.4, 26.1 , 24.6 (d, J = 5.8 Hz). ³¹ P NMR (81 .0 MHz, toluene-d ₈ ) δ 51 .2 (d, J = 29.1 Hz), 40.5 (d, J = 29.1 Hz). IR (cm ^"1 ): 1959, 1609, 1586.

Example 12: Synthesis of the complex [Ru(OAc)(CO)((R,R)-dpen)(R-Josiphos)]OAc (14)

In an NMR tube the complex Ru(OAc) ₂ (CO)(ft-Josiphos) (34) (32.0 mg, 0.04 mmol, 1 equiv) suspended in 0.6 imL of toluene-d ₈ , was reacted with the ligand (fl,fl)-dpen (8.2 mg, 0.04 mmol, 1 equiv). After stirring at room temperature for 2 h, the sample was characterized by NMR, showing that 2 isomers of the desired product were obtained in a 4/1 ratio. The sample was then dried under low pressure. Yield: 39.1 mg (97%). Anal. Calcd (%) for C ₅ 5H5 ₄ FeN2O ₅ P2Ru: C, 63.40; H, 5.22; N, 2.69; Found: C, 63.00; H, 5.40; N, 2.50. ³¹ P NMR (81 .0 MHz, toluene-d ₈ ) δ 60.4 (d, J = 35.8 Hz, minor dia), 51 .0 (d, J = 34.7 Hz, major dia), 41 .1 (d, J = 34.6 Hz, major dia), 25.7 (d, J = 35.8 Hz, minor dia). IR (cm ^"1 ): 1957, 1601 , 1558

Example 13: Synthesis of the complex [Ru(OAc)(CO)((S,S)-dpen)(R-Josiphos)]OAc (15)

In an NMR tube the complex Ru(OAc) ₂ (CO)(ft-Josiphos) (34) (29.9 mg, 0.04 mmol, 1 equiv) suspended in 0.6 mL of toluene-ds, was reacted with the ligand (S,S)-dpen (8.0 mg, 0.04 mmol, 1 equiv). After stirring at room temperature for 2 h, the sample was characterized by NMR, showing that 2 isomers of the desired product was obtained in a

7/3 ratio. The sample was then dried under low pressure. Yield: 36.7 mg (98%). Anal.

Calcd (%) for C ₅ 5H54FeN2O ₅ P2Ru: C, 63.40; H, 5.22; N, 2.69; Found: C, 63.30; H, 5.50; N, 2.60. ³¹ P NMR (81 .0 MHz, toluene-d ₈ ) δ 53.8 (d, J = 36.0 Hz, minor dia), 52.6 (d, J =

34.4 Hz, major dia), 41 .9 (d, J = 34.5 Hz, major dia), 36.1 (d, J = 36.1 Hz, minor dia). IR

(cm ^"1 ): 1956, 1602, 1562.

Example 14: Synthesis of the complex RuCI ₂ (CO)(Hamtp)(PPh ₃ ) (16)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ )2 (282.3 mg, 0.35 mmol, 1 equiv), suspended in 15 mL of CHCI ₃ , was reacted with the ligand HCNN (70.9 mg, 0.36 mmol, 1 .1 equiv). The suspension was stirred at 60 °C overnight and the volume was reduced to about 1 mL. The complex was precipitated by addition of 10 mL of n-pentane. The obtained solid was filtered, washed two times with 5 mL of ethyl ether, one time with 5 mL of n- pentane and dried under reduced pressure. Yield: 160,3 mg (69%). Anal. Calcd (%) for C32H29CI2N2OPRU :C, 58.19; H, 4.43; N, 4.24; found: C, 58.20, H, 4.40; N, 4.. ¹ H NMR (200 MHz, CD2CI2) δ 7.89 - 7.07 (m, 22H), 4.50 (t, J = 6.1 Hz, 2H), 3.13 (t, J = 5.7 Hz, 2H), 2.49 (s, 3H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 200.7 (d, J = 21 .5 Hz), 165.5, 161 .4, 140.4, 139.4, 137.1 , 134.1 (d, J = 9.6 Hz), 133.2, 132.3, 130.27, 130.2 (d, J = 2.4 Hz), 129.3, 128.3 (d, J = 10.0 Hz), 126.0 (d, J = 2.3 Hz), 1 19.8 (d, J = 1 .4 Hz), 66.0, 50.3, 21 .6 (d, J = 12.2 Hz). ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 54.5. IR (cm ^"1 ): 1947.

Example 15: Synthesis of the complex RuCI ₂ (CO)(Hambq)(PPh ₃ ) (17)

The complex RuCl2(CO)(dmf)(PPh ₃ ) ₂ (365 mg, 0.46 mmol, 1 equiv), suspended in 5 mL of n-BuOH, was reacted with the ligand Hambq (208 mg, 1 .03 mmol, 2.2 equiv). The suspension was stirred at 130 °C overnight, the solvent was evaporated under reduced pressure and the residue was dissolved in 1 mL of CHCI ₃ . The solution was stirred for 1 hour at room temperature and the complex was precipitated by addition of 10 mL ethyl ether. The solution was filtered, and the solid was washed 2 times with 3 mL of ethyl ether, one time with 3 mL of n-pentane and dried under reduced pressure. Yield: 291 mg (95%). Anal. Calcd (%) for C33H27CI2N2OPRU: C, 59.1 1 ; H, 4.06; N, 4.18, found: C, 59.20; H, 4.10; N, 4.26. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 8.12 - 6.87 (m, 23H), 4.36 - 4.14 (m, 1 H), 4.01 - 3.83 (m, 1 H), 3.54 - 3.28 (m, 1 H), 2.68 - 2.24 (m, 1 H). ³¹ P NMR (81 MHz, CD2CI2) δ 36.9. IR (cm ^"1 ): 1920.

Example 16: Synthesis of the complex RuCI ₂ (CO)(Hambq ^Ph )(PPh ₃ ) (18)

The complex RuCl2(CO)(dmf)(PPh ₃ ) ₂ (245 mg, 0.31 mmol, 1 equiv), suspended in 5 mL of n-BuOH, was reacted with the ligand HCI*Hambq ^Ph (159 mg, 0.50 mmol, 1 .6 equiv) and the base n-Bu ₃ N (0.5 mL, 2 mmol, 6.6 equiv). After stirring at 130 °C overnight, the solvent was evaporated under reduced pressure, the residue dissolved in 3 mL of CHCI3 and the base K ₂ CO ₃ (200 mg, 1 .39 mmol, 4.5 equiv) was added. The mixture was stirred for 2 h at room temperature, the mixture was filtered. The volume was reduced to about 1 mL and the complex was precipitated by addition of 10 mL ethyl ether. The solution was filtered, and the solid was washed 2 times with 3 mL of ethyl ether, one time with 3 mL of n-pentane and dried under reduced pressure. Yield: 101 mg (46%). Anal. Calcd (%) for C39H31CI2N2OPRU: C, 62.74; H, 4.18; N, 3.75, found: C, 62.66; H, 4.10; N, 3.92. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 9.21 - 9.13 (m, 1 H), 7.95 - 7.10 (m, 26H), 4.77 - 4.54 (m, 1 H), 4.26 - 4.00 (m, 1 H), 3.84 - 3.63 (m, 1 H), 3.19 - 2.98 (m, 1 H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 36.9. IR (cm ^"1 ): 1924.

Example 17: Synthesis of the complex Ru(OAc) ₂ (Hamtp)(CO)(PPh ₃ ) (19)

The complex Ru(OAc)2(CO)(PPh ₃ ) ₂ (100,3 mg, 0.13 mmol, 1 equiv), suspended in 5 mL of toluene, was reacted with the ligand Hamtp (26,7 mg, 0.13 mmol, 1 equiv). After stirring at 1 10 °C for 2 days, the solution was concentrated to V ~ 0.5 mL, and the complexe was precipitated by addition of 7 mL of n-pentane . The mixture was was filtered and the solid was washed 2 times with 5 mL of n-Heptane, two times with 3 mL of Et2O and dried under reduced pressure. Yield: 37,1 mg (40%). Anal. Calcd (%) for C36H35N2O5PRU: C, 61 .10; H, 4.98; N, 3.96, found: C, 60.90; H, 5.30; N, 3.80. ¹ H NMR (200 MHz, CD2CI2) δ 8.28 - 8.02 (m, 1 H), 7.79 - 7.60 (m, 6H), 7.46 - 7.37 (m, 6H), 7.30 - 7.17 (m, 6H), 7.10 - 7.03 (m, 1 H), 6.91 (d, J = 8.4 Hz, 1 H), 6.73 - 6.58 (m, 1 H), 4.41 (dd, J = 16.6, 6.5 Hz, 1 H), 4.32 - 4.07 (m, 2H), 3.53 - 3.30 (m, 1 H), 2.14 (s, 3H), 2.07 (s, 3H), 1 .20 (s, 3H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 54,4. IR (cm ^"1 ): 1914, 1597, 1572. Example 18: Synthesis of the complex RuCI(amtp)(CO)(PPh ₃ ) (20)

The complex RuCI(CNN)(PPh ₃ ) ₂ (251 .9 mg, 0.29 mmol, 1 equiv) was suspended in 5 mL of CH2CI2 and the mixture was stirred under CO atmosphere (1 atm) overnight at room temperature. The solvent was evaporated under reduced pressure and the residue was purified by column chromatography, eluent CH ₂ Cl2/Et ₂ O (9/1 to 1 /1 ). Yield: 173 mg (94%). Anal. Calcd (%) for C ₃ 2H ₂ 8CIN ₂ OPRu: C, 61 .59; H, 4.52; N, 4.49. Found: C, 61 .74; H, 4.85; N, 4.66. IR (cm ¹ ): 1905.

Example 19: Synthesis of the complex RuCI(ambq)(CO)(PPh ₃ ) (21)

The complex RuCI(ambq)(PPh ₃ ) ₂ (226 mg, 0.26 mmol, 1 equiv) was suspended in 5 mL of CH ₂ CI ₂ , and the mixture was stirred under CO atmosphere (1 atm) overnight at room temperature. The solvent was evaporated under reduced pressure and the residue was purified by column chromatography, eluent CH ₂ CI ₂ /Et ₂ O (9/1 to 1/1 ). Yield: 132 mg (80%). Anal. Calcd (%) for C ₃₃ H ₂₆ CIN ₂ OPRu: C, 62.51 ; H, 4.13; N, 4.42. Found:C, 62.55; H, 4.10; N, 4.37. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 8.06 - 7.80 (m, 2H), 7.51 - 6.92 (m, 20H), 4.53 (dd, J = 16.9, 6.7 Hz, 1 H), 4.13 - 3.96 (m, 1 H), 3.85 - 3.60 (m, 1 H), 2.76 (t, J = 8.7 Hz, 1 H) . ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 207.9 (d, J = 17.5 Hz), 172.2 (d, J = 12.8 Hz), 156.1 , 150.7, 142.5, 139.8, 135.5, 134.1 (d, J = 19.2 Hz), 133.4, 133.0 (d, J = 10.2 Hz), 133.0 (s,), 130.1 (d, J = 2.3 Hz), 129.6, 128.3 (d, J = 9.8 Hz), 125.5, 122.4, 1 19.8, 1 16.7, 51 .5. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 58.4. IR (cm ^"1 ): 1922.

Example 20: Synthesis of the complex RuCI(ambq ^Ph )(CO)(PPh ₃ ) (22)

The complex RuCI(ambq ^Ph )(PPh ₃ ) ₂ (1 19.8 mg, 0.13 mmol, 1 equiv) was suspended in 5 mL of CH ₂ CI ₂ and the mixture stirred under CO atmosphere (1 atm) at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was purified by column chromatography, eluent CH ₂ CI ₂ /Et ₂ O (9/1 to 1 /1 ). Yield: 76.6 mg (85%). Anal. Calcd (%) for C ₃₉ H ₃₀ CIN ₂ OPRu: C, 65.96; H, 4.26; N, 3.94. Found: C, 66.31 ; H, 3.33; N, 4.12. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 8.17 - 6.89 (m, 26H), 4.57 (dd, J = 16.9, 6.5 Hz, 1 H), 4.14 (dd, J = 17.4, 10.0 Hz, 1 H), 3.83 (dd, J = 17.0, 7.6 Hz, 1 H), 2.99 (dd, J = 9.1 , 7.0 Hz, 1 H) . ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 208.0 (d, J = 17.4 Hz, CO), 172.6 (d, J = 12.8 Hz, Ru-C), 155.8, 150.9, 148.7, 142.7, 139.9, 138.0, 134.0 (d, J = 9.1 Hz), 133.1 , 132.9, 132.9, 130.0 (d, J = 2.4 Hz), 129.9, 129.6, 129.1 , 128.8, 128.3 (d, J = 9.8 Hz), 123.6, 120.6, 1 19.6, 1 17.2, 51 .5. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 58.8. IR (cm ^"1 ): 1920. Example 21 : Synthesis of the complex RuCI[(2-CH2-6-Me-C ₆ H ₃ )PCy2](CO)(en) (23) In an NMR tube the complex RuCI[(2-CH ₂ -6-Me-C ₆ H3)PCy2](CO)[(2,6-Me2C ₆ H3)PCy ₂ ] (25) (15.5 mg, 0.02 mmol, 1 equiv) was dissolved in 0.6 imL of CD2CI2. The ligand en (3 μΙ_, 0.04 mmol, 2 equiv) was added. The solution was heated at 50 °C for two days. The ³¹ P NMR analysis of the tube showed the displacement of one ligand PCy ₂ (Xylyl) and the formation of two isomers of the desired complex 23. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 97.4 (s, 1 %), 84.5 (s, 35%), 81 .1 (s, 23 %), 53.1 (s, 5%, OPCy ₂ (Xylyl)), -4.23 (s, 37%, PCy ₂ (Xylyl)).

Example 22: Synthesis of the complex RuCI[(2-CH2-6-Me-C ₆ H ₃ )PCy2](CO)(ampy) (24) In an NMR tube the complex RuCI[(2-CH ₂ -6-Me-C ₆ H3)PCy2](CO)[(2,6-Me2C ₆ H3)PCy ₂ ] (25) (15.5 mg, 0.02 mmol, 1 equiv) was dissolved in 0.6 imL of CD2CI2. The ligand en (3 μΙ_, 0.04 mmol, 2 equiv) was added. The solution was heated at 50 °C for two days with formation of complex 24.

Example 23: Synthesis of the complex RuCI[(2-CH2-6-Me-C ₆ H ₃ )PCy ₂ ](CO)[(2 _; 6-

The complex RuCl3*xH ₂ O (109 mg, 0.43 mmol, 1 equiv), suspended in 4 imL of EtOH, was reacted with the ligand (2,6-Me2C ₆ H ₃ )PCy2 (345 mg, 1 .14 mmol, 2.7 equiv) and the base Et ₃ N (250 μΙ_, 1 .84 mmol, 4.3 equiv). After stirring at 80 °C for 1 h, formaldehyde (300 μΙ_, 37% solution in water, 3.70 mmol, 8.6 equiv) was added and the mixture was stirred at 80 °C overnight. The volume was reduced to about half and the obtained precipitated was filtered. The solid was washed two times with 2 imL of EtOH, once with 2 imL of Et ₂ O and dried under reduced pressure. Yield: 107 mg (32%). Anal. Calcd (%) for C ₄₁ H ₆₁ CIOP ₂ Ru: C, 64.09; H, 8.00, Found: C, 63.99; H, 8.95. ¹ H NMR (200 MHz, CD2CI2) δ 7.32 - 6.86 (m, 6H), 3.78 (d, J = 12.9 Hz, 1 H), 3.58 (dd, J = 15.0, 6.7 Hz, 1 H), 2.97 - 1 .1 1 (m, 53H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 201 .6 (dd, J = 14.4, 12.1 Hz), 163.7 (dd, J = 33.6, 4.2 Hz), 140.8 (d, J = 1 .4 Hz), 133.8 (d, J = 3.0 Hz), 131 .3 (d, J = 1 .4 Hz), 130.9 (d, J = 1 .7 Hz), 130.5 (d, J = 2.5 Hz), 130.1 (d, J = 2.1 Hz), 129.8 (d, J = 0.9 Hz), 129.5 (d, J = 2.4 Hz), 129.1 (d, J = 1 .1 Hz), 128.9 (d, J = 1 .3 Hz), 127.7 (d, J = 5.5 Hz), 126.0 (d, J = 14.4 Hz), 41 .7 (d, J = 19.2 Hz), 40.6, 39.4 (d, J = 13.7 Hz), 39.2 (d, J = 8.1 Hz), 35.4 (d, J = 13.9 Hz), 33.9 (d, J = 25.5 Hz), 32.6 (d, J = 5.9 Hz), 31 .6 (d, J = 4.6 Hz), 30.8 (d, J = 10.5 Hz), 30.6 (d, J = 3.1 Hz), 30.1 (d, J = 4.1 Hz), 29.9, 29.6 (d, J = 4.0 Hz), 29.3, 28.8 (d, J = 8.5 Hz), 28.5 - 25.8 (m), 23.7 (d, J = 2.2 Hz), 23.2 (t, J = 4.0 Hz), 22.7. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 67.2 (d, J = 281 .4 Hz), 40.0 (d, J = 281 .6 Hz). IR (cm ^"1 ): 1903. Example 24: Synthesis of RuCI ₂ (CO)(dppb)(PPh ₃ ) (27)

The complex RuCl ₂ (CO)(dmf)(PPh ₃ ) ₂ (100.9 mg, 0.13 mmol, 1 equiv) suspended in 5 mL of CHCI3, was reacted with the ligand dppb (54.6 mg, 0.13 mmol, 1 equiv). After stirring at 60 °C overnight, the solution was concentrated to about 1 mL. The complex was precipitated by addition of 10 mL n-heptane. The obtained solid was filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 1 12.4 mg (75%). Anal. Calcd (%) for C ₄ 7H ₄₃ Cl ₂ OP ₃ Ru: C, 63.52; H, 4.88 Found: C, 64.93; H, 5.99. ¹ H NMR (200 MHz, CDCI ₃ ) δ 7.85 - 7.70 (m, 4H), 7.66 - 6.97 (m, 28H), 6.89 - 6.69 (m, 3H), 3.15 - 2.95 (m, 1 H), 2.72 - 2.40 (m, 3H), 2.34 - 2.16 (m, 2H), 1 .77 - 1 .52 (m, 2H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 27.5 (t, J = 25.8 Hz, 1 P), 16.4 - 14.8 (m, 2P). IR (cm ^"1 ): 1954.

Example 25: Synthesis of RuCI ₂ (CO)(dppf) (28)

The complex RuCl ₂ (CO)(dmf)(PPh ₃ ) ₂ (199.3 mg, 0.25 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand dppf (141 .3 mg, 0.25 mmol, 1 equiv). After stirring the mixture at 1 10 °C for 2 h, the obtained solution was concentrated to about 1 mL, 10 mL n-heptane were added and the suspension was stirred at room temperature for 1 h. The precipitate was filtered, the obtained solid was washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 99.5 mg (39%). Anal. Calcd (%) for C ₃₅ H ₂₈ CI ₂ FeOP ₂ Ru: C, 55.73; H, 3.74 Found: C, 55.41 ; H, 3.33. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 53.6 (d, J = 27.2 Hz), 46.6 (d, J = 26.8 Hz). IR (cm ^"1 ): 1979.

Example 26: Synthesis of RuCI ₂ (CO)((R)-Josiphos)(PPh ₃ ) (29)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ (300.0 mg, 0.38 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand (fl)-Josiphos (225.2 mg, 0.39 mmol, 1 equiv). After stirring the mixture at 1 10 °C 2 h, the obtained solution was concentrated to about 1 mL. The complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 345.8 mg. Anal. Calcd (%) for C55H ₄ 7CI ₂ FeOP ₃ Ru: C, 63.23; H, 4.53; Found: C, 62.90; H, 4.20. ³¹ P NMR (81 MHz, CD ₂ CI ₂ ) δ 47.5 (t, J = 22.9 Hz), 13.6 (d, J = 22.7 Hz). IR (cm ^"1 ): 1979.

Example 27: Synthesis of RuCI ₂ (CO)((R)-BINAP)(PPh ₃ ) (30)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ (299.7 mg, 0.38 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand (fl)-BINAP (239.8 mg, 0.39 mmol, 1 equiv). After stirring at 1 10 °C 2 h, the obtained solution was concentrated to about 1 mL. The complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 359.7 mg (87%). Anal. Calcd (%) for CesH^C OPaRu: C, 69.68; H, 4.37; Found: C, 69.80; H, 4.10. IR (cm ¹ ): 1981

Example 28: Synthesis of RuCI ₂ (CO)((R,R)-Skewphos)(PPh ₃ ) (31)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ )2 (201 .1 mg, 0.26 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand {R,R)- Skewphos (1 13.0 mg, 0.26 mmol, 1 equiv). After stirring at 1 10 °C 2 h, the solution was concentrated to about 1 mL. The complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 150.5 mg (65%). IR (cm ^"1 ): 1976.

Example 29: Synthesis of Ru(OAc) ₂ (CO)(dppb) (32)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (300.3 mg, 0.39 mmol, 1 equiv) suspended in 5 mL of CH2CI2, was reacted with the ligand dppb (167.3 mg, 0.39 mmol, 1 equiv). After stirring the mixture at room temperature overnight, the obtained solution was concentrated to about 0.5 mL. The complex was precipitated by addition of 10 mL n- heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 230.1 mg (88%). Anal. Calcd (%) for C33H34O5P2RU: C, 58.84; H, 5.09 Found: C, 58.50; H, 5.10. ¹ H NMR (200 MHz, CDCI3, 25 °C) δ 7.92 - 7.12 (m, 20H), 2.84 (m, 2H), 2.43 (m, 2H), 1 .79 (m, 4H), 1 .41 (s, 6H). ¹ H NMR (200 MHz, CDCI ₃ , -70 °C) δ 8.07 - 7.77 (m, 3H), 7.73 - 7.19 (m, 15H), 7.15 - 6.92 (m, 2H), 3.37 - 2.36 (m, 3H), 2.29 - 1 .38 (m, 5H), 1 .34 (s, 3H), 1 .14 (s, 3H). ¹³ C NMR (50 MHz, CD2CI2, 25 °C) δ 204.6 (broad), 133.77 - 132.48 (m), 130.80 (d, J = 25.6 Hz), 129.07 - 128.33 (m), 30.40 (s, broad), 29.75 (s, broad), 23.79 (s, broad), 23.53 (s, broad). ¹³ C NMR (50 MHz, CD ₂ CI ₂ , -70 °C) δ 204.5 (dd, J = 21 .6, 15.8 Hz), 202.7 (t, J = 16.9 Hz), 189.1 , 182.4 (t, J = 38.8 Hz), 175.3, 136.8 (d, J = 51 .5 Hz), 133.4 (d, J = 18.8 Hz), 131 .8, 131 .2 - 130.5 (m), 130.4 (d, J = 8.7 Hz), 129.4 (d, J = 17.3 Hz), 129.1 - 128.5 (m), 128.0 (d, J = 8.9 Hz), 127.8 (d, J = 9.5 Hz) 29.9 (d, J = 35.3 Hz), 27.7 (d, J = 33.5 Hz), 25.2, 24.4, 21 .9 (d, J = 4.3 Hz), 20.5. ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 46.7 (broad). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , -70 °C) δ 48.0 (d, J = 27.1 Hz), 46.3 (d, J = 25.9 Hz), 38.7 (s, broad). IR (cm ^"1 ): 1954, 1945.

Example 30: Synthesis of Ru(OAc) ₂ (CO)(dppf) (33) The complex Ru(OAc) ₂ (CO)(PPh ₃ )2 (200.5 mg, 0.26 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand dppf (167.3 mg, 0.26 mmol, 1 equiv). After stirring at 1 10 °C for 2 h, the solution was concentrated to about 1 mL and the complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 139.6 mg (67%) determined to be a mixture of 3 isomers in a ratio of 7/2/1 at -70 °C, the mixture is interchanging at room temperature. Anal. Calcd (%) for C ₃ 9H ₃₄ FeO5P ₂ Ru: C, 58.44; H, 4.28; Found: C, 58.10; H, 4.60. ¹ H NMR (200 MHz, CDCI ₃ , 25 °C) δ 7.95 - 7.14 (m broad, 20 H), 4.68 - 4.24 (m broad, 8H), 1 .56 (s broad, 6H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ , 25 °C) δ 134.9 - 133.1 (m), 130.7 (d, J = 16.0 Hz), 129.1 - 127.2 (m), 75.5 (d, J = 36.2 Hz), 73.1 , 72.6, 24.2 (s, broad). ¹³ C NMR (50 MHz, CD ₂ CI ₂ , -70 °C) δ 203.07 (t, J = 16.5 Hz), 182.69 (s), 181 .93 (s), 134.64 (dd, J = 22.9, 9.9 Hz), 132.95 (d, J = 9.7 Hz), 132.24 - 130.81 (m), 129.84 (s), 127.92 - 126.43 (m), 78.20 - 76.66 (m), 75.95 (d, J = 5.4 Hz), 75.53 - 74.02 (m), 72.71 (s), 71 .80 (d, J = 6.1 Hz), 71 .14 (d, J = 5.4 Hz), 25.40 (s), 24.47 (d, J = 4.8 Hz). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 50.8 (s broad). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , -70 °C) δ 53.1 (d, J = 27.1 Hz, 10%), 52.0 (d, J = 26.7 Hz, 23%), 49.8 (d, J = 30.4 Hz), 45.4 (d, J = 30.4 Hz, 67%), 43.5 (d, J = 26.8 Hz, 10%). IR (cm ^"1 ): 1974, 1613.

Example 31 : Synthesis of Ru(OAc) ₂ (CO)((R)-Josiphos) (34)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (300.3 mg, 0.39 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand (fl)-Josiphos (167.3 mg, 0.40 mmol, 1 equiv). After stirring at 1 10 °C for 2 h, the homogenous solution, was concentrated to about 1 mL and the complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure, leading to a mixture of two diastereoisomers of the product in a 3/2 ratio. Yield: 273.6 mg (85%). Anal. Calcd (%) for C ₄₁ H ₃₈ FeO ₅ P ₂ Ru: C, 59.36; H, 4.62 Found: C, 59.30; H, 4.30. ¹ H NMR (200 MHz, CD ₂ CI ₂ , 25 °C) δ 8.25 - 7.99 (m, 3H), 7.70 - 7.07 (m, 31 H), 7.05 - 6.87 (m, 2H), 6.72 - 6.46 (m, 2H), 4.81 (s, 1 H, maj dia), 4.65 (s, 1 H min dia), 4.49 (s, 1 H), 4.44 - 4.32 (m, 2H), 4.24 - 4.00 (m, 2H), 3.91 (s, 3H min dia), 3.76 (s, 5H maj dia), 2.09 - 1 .65 (m, 4H), 1 .51 - 1 .25 (m, 8H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 67.2 (broad, maj dia), 46.5 (broad, maj dia), 35.9 (broad, min dia), 30.5 (broad, min dia). IR (cm ^"1 ): 1975, 1950, 1614, 1568.

Example 32: Synthesis of Ru(OAc) ₂ (CO)((R)-BINAP) (35) The complex Ru(OAc) ₂ (CO)(PPh ₃ )2 (300.7 mg, 0.39 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand (fl)-BINAP (243 mg, 0.39 mmol, 1 equiv). After stirring at 1 10 °C for 2 h, the solution was concentrated to about 1 mL. The complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 314.1 mg (93%). Anal. Calcd (%) for C ₄₉ H38O ₅ P2Ru: C, 67.66; H, 4.40 Found: C, 68.00; H, 4.30. ¹ H NMR (200 MHz, CD ₂ CI ₂ , 25 °C) δ 7.97 - 7.81 (m, 2H), 7.71 - 7.27 (m, 20H), 7.24 - 6.99 (m, 4H), 6.92 - 6.52 (m, 6H), 1 .29 (s, 6H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 49.87 (s broad), 43.21 (s broad). IR (cm ^"1 ): 1968, 1616, 1505.

Example 33: Synthesis of Ru(OAc) ₂ (CO)((R,R)-Skewphos) (36)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (200.9 mg, 0.26 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand (fl,fl)-Skewphos (1 14 mg, 0.26 mmol, 1 equiv). After stirring at 1 10 °C for 2 h, the solution was concentrated to about 1 mL and the complex was precipitated by addition of 10 mL n-heptane, filtered, washed 3 times with 4 mL of n-heptane, 3 times with 3 mL of Et ₂ O and dried under reduced pressure. Yield: 127.9 mg (71 %). Anal. Calcd (%) for C ₃₄ H ₃ 6O ₅ P ₂ Ru: C, 59.38; H, 5.28 Found: C, 59.20; H, 4.90; N, 4.10. ¹ H NMR (200 MHz, CD ₂ CI ₂ , 25 °C) δ 7.78 - 7.34 (m, 16H), 7.32 - 7.08 (m, 4H), 3.28 - 3.03 (m, 1 H), 2.85 - 2.64 (m, 1 H), 2.26 - 2.06 (m, 1 H), 2.00 - 1 .77 (m, 1 H), 1 .57 (s broad, 6H), 0.95 (ddd, J = 19.4, 14.0, 7.1 Hz, 6H). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 55.0 (s, broad), 50.9 (s, broad). IR (cm-1 ): 1958, 1568.

Example 34: Synthesis of RuCI ₂ (CO)(dppb)(HCN) (37)

The complex RuCI ₂ (CO)(dmf)(PPh ₃ ) ₂ (159.1 mg, 0.20 mmol, 1 equiv) suspended in 3 mL of CH ₂ CI ₂ , was reacted with the ligand dppb (85.3 mg, 0.20 mmol, 1 equiv) and stirred at room temperature for 2 h. The solution was dried under vacuum and 2- propanol (3 ml) and the ligand HCN (0.3 mmol, 33 μΙ, 1 .5 eq.) were sequentially added to the obtained residue and the mixture refluxed for 2.5 h. The solvent was evaporated under reduced pressure and the crude product was treated with n-pentane and refluxed for 0.5 h. The precipitated complex was filtrated, washed 3 times with 4 mL of pentane and dried under reduced pressure. Yield: 92 mg (63%). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 47.6 (d, J = 30.2 Hz), 28.2 (d, J = 30.2 Hz).

Example 35: Synthesis of Ru(OAc) ₂ (CO)(dppb)(HCN) (38)

The complex Ru(OAc) ₂ (CO)(PPh ₃ ) ₂ (154.3 mg, 0.20 mmol, 1 equiv) suspended in 3 mL of CH ₂ CI ₂ , was reacted with the ligand dppb (85.3 mg, 0.20 mmol, 1 equiv) and stirred at room temperature for 2 h. The solvent was evaporated under reduced pressure and 2-propanol (3 ml) and the ligand HCN (0.3 mmol, 33 μΙ, 1 .5 eq.) were sequentially added and the mixture was refluxed for 2.5 h. The solvent was evaporated under reduced pressure and the crude product was treated with pentane and refluxed for 0.5 h (3 x 3 ml). The precipitated complex was filtrated and dried under reduced pressure. Yield: 90 mg (58%). ³¹ P NMR (81 MHz, CD ₂ CI ₂ , 25 °C) δ 45.1 (d, J = 29.1 Hz), 34.7 (d, J = 29.1 Hz).

Example 36: Synthesis of Ru(OAc) ₂ (CO)(PNN) (39)

The complex Ru(OAc) ₂ (CO)(PPh ₃ )2 (201 .2 mg, 0.26 mmol, 1 equiv) suspended in 5 mL of toluene, was reacted with the ligand PNN (101 .4 mg, 0.27 mmol, 1 equiv). After stirring at 1 10 °C for 2 h, the solution was concentrated to about 1 imL The complex was precipitate by addition of 10 mL n-heptane, filtrated, washed 3 times with 4 imL of n-heptane, 3 times with 3 mL of ethyl ether and dried under reduced pressure. Yield: 142.1 mg (87%). Anal. Calcd (%) for C30H29N2O5PRU: C, 57.23; H, 4.64; N, 4.45 Found: C, 57.60; H, 4.50; N, 4.10. ¹ H NMR (200 MHz, CD ₂ CI ₂ ) δ 9.04 - 8.92 (m, 1 H), 8.36 (s, 1 H, N-H), 7.93 - 7.56 (m, 6H), 7.56 - 7.32 (m, 6H), 7.32 - 7.12 (m, 4H), 6.97 - 6.83 (m, 1 H), 4.15 - 4.07 (m, 2H), 3.82 - 3.64 (m, 1 H), 3.52 - 3.36 (m, 1 H), 1 .55 (s, 3H), 1 .25 (s, 3H). ¹³ C NMR (50 MHz, CD ₂ CI ₂ ) δ 205.0 (d, J = 16.5 Hz), 176.5, 176.2, 168.5 (d, J = 5.7 Hz), 161 .3, 151 .7, 138.3, 137.9, 135.8 (d, J = 8.7 Hz), 134.6 (d, J = 9.9 Hz), 134.1 , 134.1 (d, J = 10.3 Hz), 132.6 (d, J = 6.3 Hz), 131 .5 (d, J = 2.1 Hz), 130.8 (d, J = 2.6 Hz), 130.7 (d, J = 3.6 Hz), 130.0, 129.4, 128.7 (d, J = 10.3 Hz), 128.2 (d, J = 10.5 Hz), 125.1 (d, J = 2.8 Hz), 122.8 (d, J = 2.3 Hz), 63.5, 37.2, 24.4, 23.6 . 31 P NMR (81 MHz, CD ₂ CI ₂ ) δ 49.0. IR (cm-1 ): 1940, 1626, 1607.

Example 37: catalytic reduction by transfer hydrogenation of ketones and aldehydes with complexes of examples 1-39.

The catalyst solution was prepared in a 10 mL Schlenk by adding 5 mL of 2-propanol to the chosen ruthenium complex (0.02 mmol). By stirring, the complex dissolved over a period of a few minutes. Separately, in a second Schlenk (20 mL), 250 μΐ of the previously prepared solution containing the catalyst and 200 μΐ of a 0.1 M sodium iso- propoxide solution in 2-propanol were added successively to a ketone or aldehyde solution (1 mmol) in 10 mL of 2-propanol under reflux (S/C = 1000, S/B = 50).

For the reactions, in which the catalyst was formed in situ, a pre-catalyst solution was prepared by adding 5 mL of 2-propanol to the pre-catalyst (0.02 mmol) and the corresponding ligand (0.1 mmol) (see Tables 2 and 3) and the solution was stirred for 30 min at reflux. The solution of the in situ formed catalyst was used in the reduction reaction as described above (S/C = 1000, L/C = 5, S/B = 50).

The start of the reaction was considered to be when the base was added. The molar ratio of substrate/catalyst (S/C) varied from 1000/1 to 50000/1 while the molar ratio substrate/base was in the range of 10/1 to 100/1 .

The reaction temperature was kept at 82 °C.

The results of the GC analysis for the reduction of acetophenone are reported in Table 2, while those for other ketones and aldehydes are shown in Table 3.

Table 2. Catalytic transfer hydrogenation of acetophenone (0.1 M) to 1- phenylethanol with the complexes 1-39 and NaOiPr or K ₂ C0 ₃ as base

Conversion

Complex S/C Ligand Base (S/B)

% (min) TOF (h ^"1 ) ^a ee (%)

1 1000 - NaO/Pr (50/1 ) 54 (90) -

2 1000 - NaO/Pr (50/1 ) 42 (60) -

3 1000 - NaO/Pr (50/1 ) 27 (90)

4+5 1000 - NaO/Pr (50/1 ) 81 (90)

6+7 1000 - NaO/Pr (50/1 ) 95 (90)

8 1000 - NaO/Pr (50/1 ) 90 (90)

9 1000 - NaO/Pr (50/1 ) 88 (90)

16 1000 - NaO/Pr (50/1 ) 100 (2) 12000

16 10000 - NaO/Pr (50/1 ) 100 (36) 8000

18 10000 - NaO/Pr (50/1 ) 100 (17) 20000

20 10000 - NaO/Pr (50/1 ) 100 (0.06) 86000

20 50000 - NaO/Pr (50/1 ) 100 (0.45) 55000

21 1000 - K ₂ C0 ₃ (20/1 ) 95 (30)

21 1000 - NaO/Pr (50/1 ) 96 (15)

22 10000 - NaO/Pr (50/1 ) 100 (17) 18000

27 1000 en NaO/Pr (50/1 ) 25 (120) -

27 1000 ampy NaO/Pr (50/1 ) 38 (120) -

28 1000 en NaO/Pr (50/1 ) 44 (120) -

28 1000 ampy NaO/Pr (50/1 ) 90 (120) 3500

29 1000 en NaO/Pr (50/1 ) 74 (120) 400 13

29 1000 ampy NaO/Pr (50/1 ) 95 (120) 1700 17

29 1000 (±)iPr-ampy NaO/Pr (50/1 ) 97 (30) 6700 17

29 1000 (R.R)-DPEN NaO/Pr (50/1 ) 96 (120) 1200 59

29 1000 (S.S)-DPEN NaO/Pr (50/1 ) 94 (120) 700 32

30 1000 en NaO/Pr (50/1 ) 92 (120) 900 22

30 1000 ampy NaO/Pr (50/1 ) 88 (300) 300 18 30 1000 (±)iPr-ampy NaO/Pr (50/1 ) 97 (120) 1200 25

30 1000 (R.R)-DPEN NaO/Pr (50/1 ) 93 (120) 8400 32

30 1000 (S.S)-DPEN NaO/Pr (50/1 ) 78 (120) 1 100 16

31 1000 en NaO/Pr (50/1 ) 48 (120) - 13

31 1000 ampy NaO/Pr (50/1 ) 86 (120) 1800 66

31 1000 (±)iPr-ampy NaO/Pr (50/1 ) 95 (30) 5800 67

31 1000 (R.R)-DPEN NaO/Pr (50/1 ) 85 (120) 800 46

31 1000 (S.S)-DPEN NaO/Pr (50/1 ) 46 (120) 300 53

32 1000 en NaO/Pr (50/1 ) 85 (120) 3700

32 1000 ampy NaO/Pr (50/1 ) 93 (120) 7400

33 1000 en NaO/Pr (50/1 ) 46 (120) -

33 1000 ampy NaO/Pr (50/1 ) 72 (120) 6850

34 1000 en NaO/Pr (50/1 ) 91 (120) 1200 9

34 1000 ampy NaO/Pr (50/1 ) 94 (30) 10650 2

34 1000 (±)iPr-ampy NaO/Pr (50/1 ) 94 (5) 16000 22

34 1000 (R.R)-DPEN NaO/Pr (50/1 ) 96 (30) 16000 23

34 1000 (S.S)-DPEN NaO/Pr (50/1 ) 96 (30) 16000 1

35 1000 en NaO/Pr (50/1 ) 97 (30) 6000 18

35 1000 ampy NaO/Pr (50/1 ) 94 (5) 16800 23

35 1000 (±)iPr-ampy NaO/Pr (50/1 ) 97 (5) 19200 24

35 1000 (R.R)-DPEN NaO/Pr (50/1 ) 97 (5) 15000 30

35 1000 (S.S)-DPEN NaO/Pr (50/1 ) 96 (5) 12000 19

36 1000 en NaO/Pr (50/1 ) 91 (30) 10100 25

36 1000 ampy NaO/Pr (50/1 ) 95 (30) 10100 25

36 1000 (±)iPr-ampy NaO/Pr (50/1 ) 90 (5) 15100 39

36 1000 (R.R)-DPEN NaO/Pr (50/1 ) 97 (30) 17700 12

36 1000 (S.S)-DPEN NaO/Pr (50/1 ) 92 (30) 15200 26

39 1000 - NaO/Pr (50/1 ) 96 (30) 13900 - ^a TOF = turnover frequency (moles of carbonyl compound converted to alcohol per mole of catalyst per hour) at 50% conversion. Table 3. Catalytic transfer hydrogenation of ketones and aldehydes (0.1 M) to alcohols with the complexes 1-21 using a ratio substrate/base (NaOiPr) of 50/1

Example 38: catalytic reduction of ketones with complexes of examples 1 -36 using molecular hydrogen

The hydrogenation reactions were performed in an 8 vessels Endeavor Parr apparatus. The vessels were charge with the catalysts (2.5 μιηοΙ). The vessels were closed, charged with 5 bar of N ₂ and slowly vented five times. The ketone (5 mmol), optionally ligand (5 μιηοΙ), the solvent (0.9 mL) and 1 mL of a solution of f-BuOK 0.1 M were added. The vessels were charged with 20 bar of H ₂ and slowly vented four times. The vessel was charged to 30 bars and heated to 70 °C (S/C = 2000, S/B = 50, L/C = 2). The molar ratio of substrate/catalyst varied from 2000/1 to 25000/1 while the molar substrate/base ratio range from 10/1 to 100/1 .

The hydrogen uptake was calculated by the apparatus and the results of the GC analysis at the end of the runs are shown in Tables 4 for the catalytic reduction of acetophenone and in Table 5 for other substrates.

For the in situ reactions, the vessel was charge with the precursor catalyst (2.5 μιηοΙ) and the corresponding ligand (5 μιηοΙ) (L/C = 2/1 ) (see Tables 4 and 5). Table 4. Catalytic hydrogenation (30 bar) of acetophenone to 1-phenylethanol in the presence of the complexes 1-25 using i-BuOK or KOH as base

Complex S/C ligand solvent Base (S/B) conversion

%(h)

1 2000 - EtOH f-BuOK (50/1 ) 100 (16)

2 2000 - EtOH f-BuOK (50/1 ) 100 (16)

3 2000 - EtOH f-BuOK (50/1 ) 100 (16)

8 2000 - EtOH f-BuOK (50/1 ) 100 (16)

16 2000 - MeOH f-BuOK (20/1 ) 63 (16)

17 2000 - MeOH f-BuOK (20/1 ) 100 (16)

20 2000 - EtOH f-BuOK (50/1 ) 61 (16)

20 2000 - MeOH f-BuOK (20/1 ) 25 (16)

21 2000 - EtOH f-BuOK (50/1 ) 43 (16)

21 2000 - MeOH f-BuOK (20/1 ) 13 (16)

22 2000 - EtOH f-BuOK (50/1 ) 42 (16)

22 2000 - MeOH f-BuOK (20/1 ) 36 (16)

25 2000 - EtOH f-BuOK (50/1 ) 72 (16)

25 2000 en EtOH f-BuOK (50/1 ) 100 (16)

25 2000 ampy EtOH f-BuOK (50/1 ) 100 (16)

25 10000 en EtOH f-BuOK (50/1 ) 100 (16)

25 10000 ampy EtOH f-BuOK (50/1 ) 92 (16)

25 10000 en MeOH f-BuOK (50/1 ) 28 (16)

25 10000 ampy MeOH f-BuOK (50/1 ) 81 (16)

25 10000 en MeOH KOH (50/1 ) 27 (16)

25 10000 ampy MeOH KOH (50/1 ) 91 (16)

25 25000 en MeOH KOH (50/1 ) 15 (16)

25 25000 ampy MeOH KOH (50/1 ) 45 (16)

Table 5. Catalytic hydrogenation (30 bar) of ketones to alcohols in the presence of the complexes 1-25 in ethanol using a ratio substrate/ f-BuOK of 50/1

Conversion

Complex Ketone S/C Ligand

% (h)

2 tetralone 10000 8 (16)

2 2'-Me-acetophenone 10000 100 (16)

2 4'-MeO-acetophenone 500 100 (3)

2 4'-NC>2-acetophenone 10000 10 (16)

2 benzophenone 500 100 (3)

2 benzoin 10000 5 (16)

2 2'-CI-acetophenone 10000 100 (16)

8 tetralone 10000 4 (16)

8 2'-Me-acetophenone 10000 28 (16)

8 4'-MeO-acetophenone 500 75 (3)

8 4'-NC>2-acetophenone 10000 1 (16)

8 benzophenone 500 100 (3)

8 benzoin 10000 9 (16)

8 2'-CI-acetophenone 10000 100 (16)

16 tetralone 10000 2 (16)

16 2'-Me-acetophenone 10000 76 (16)

16 4'-MeO-acetophenone 500 76 (3)

16 4'-NC>2-acetophenone 10000 5 (16)

16 benzophenone 500 99 (3)

16 benzoin 10000 7 (16)

16 2'-CI-acetophenone 10000 84 (16)

25 2-octanone 1000 ampy 36 (3)

25 isobutyrophenone 1000 ampy 61 (3)

25 tetralone 10000 ampy 7 (16)

25 tetralone 10000 en 3 (16)

25 2'-Me-acetophenone 10000 ampy 38 (16)

25 2'-Me-acetophenone 10000 en 100 (16)