Vincent Ritleng

Abstract: Cyclopentadienyl N-heterocyclic carbene (NHC) nickel complexes of general formula [Ni(R-NHC-nBu)XCp] [R-NHC-nBu = 1-butyl-3-methyl-, 1-isopropyl-3-butyl-, 1-phenyl-3-butyl-, 1-(2,4,6-trimethylphenyl)-3-butyl-, 1-(2,6-diisopropylphenyl)-3-butyl-imidazol-2-ylidene; X = Cl or I; Cp = η5-C5H5], which bear a n-butyl side-chain attached to one of the nitrogen atom of the NHC ring, were synthesized as models for trialkoxysilylpropyl-substituted complexes. They were prepared by the direct reactions of nickelocene with the corresponding imidazolium salts (R-NHC-nBu•HX). The new complexes [Ni(Me-NHC-nBu)ClCp] 1a, [Ni(iPr-NHC-nBu)ClCp] 1b, [Ni(Ph-NHC-nBu)ICp] 1c, [Ni(Mes-NHC-nBu)ICp] 1d and [Ni(iPr2Ph-NHC-nBu)ICp] 1e were obtained in moderate to good yields and were fully characterized by standard spectroscopic techniques, and in the cases of 1a, b, d and e by single X-ray crystallography. The bulky electron-rich pentamethylcyclopentadienyl derivatives, [Ni(Mes-NHC-nBu)ICp*] 2d and [Ni(iPr2Ph-NHC-nBu)ICp*] 2e (Cp* = η5-C5Me5), were prepared from reactions of in situ prepared [Ni(acac)Cp*] with the corresponding carbene precursors. Both Cp* complexes were also fully characterized spectroscopically, and their structures were established by single X-ray crystallography. All new complexes catalyzed the Suzuki-Miyaura cross-coupling of phenylboronic acid with aryl halides in the absence of co-catalysts or reductants. However, the small dialkyl-substituted species 1a and 1b proved to be the least efficient. In addition, in contrast to our previous results with the closely related diaryl substituted species [Ni(Ar2NHC)LCp†] (L = Cl-, NCMe (PF6-); Cp† = Cp, Cp*), in which complexes that bear the electron-rich Cp* ligand were much more active than those bearing the Cp ligand, no substantial catalytic behavior differences were observed between the Cp complexes 1d, e and their Cp* counterparts 2d, e. A TOF of up to 352 h-1, a so far unprecedented rate for nickel(II) complexes under similar conditions, was even observed with the Cp complex 1d. In view of these encouraging results, the triethoxysilylpropyl-substituted analogue of 1d, [Ni(Mes-NHC-TES)ClCp] 1d-TES (Mes-NHC-TES = 1-(2,4,6-trimethylphenyl)-3-[3-(triethoxysilyl)propyl]-imidazol-2-ylidene), was prepared, fully characterized and tested catalytically. As it showed similar catalytic activity to 1d, it was heterogenized on alumina to give 1d-Al. The latter species, however, exhibited a greatly reduced catalytic activity compared to 1d and 1d-TES. Possible reasons for both the excellent activities of 1d and 1d-TES, and the disappointing activity of 1d-Al are discussed.

Abstract: Cyclopentadienyl N-heterocyclic carbene (NHC) Ni complexes [Ni(NHC)XCp] (NHC = 1-(propylnitrile)-3-methylimidazol-2-ylidene, 1-(2,4,6-trimethylphenyl)-3-(butylnitrile)imidazol-2-ylidene, 1-(2,4,6-trimethylphenyl)-3-(pentylnitrile)imidazol-2-ylidene, 1-(2,4,6-trimethylphenyl)-3-(hexylnitrile)imidazol-2-ylidene; X = Cl, Br, I; Cp = η5-C5H5), which bear an alkylnitrile side chain attached to one of the N atoms of the NHC ring, were prepd. by the direct reaction of nickelocene with the corresponding imidazolium salts (NHC·HX).  [Ni{Me-NHC-(CH2)2CN}ICp] (1a), [Ni{Mes-NHC-(CH2)3CN}ClCp] (1b), [Ni{Mes-NHC-(CH2)4CN}ICp] (1c) and [Ni{Mes-NHC-(CH2)5CN}BrCp] (1d) were obtained in 43% to 71% yields and were fully characterized by std. spectroscopic techniques and elemental analyses and, in the cases of 1a,b, by single-crystal x-ray crystallog.  Structural studies established their two-legged piano-stool geometry.  The cationic derivs. [Ni{Mes-NHC-(CH2)nCN}(NCMe)Cp]+ (2b-d; n = 3-5) were prepd. from the reaction of their neutral homologs 1b-d with KPF6 in MeCN at room temp.  Upon treatment of the neutral complexes 1 or of the cationic compds. 2 with KOtBu, a C-H bond α to the nitrile group in each mol. underwent a base-promoted C-H activation and the new nickelacyclic complexes [Ni{Me-NHC-CH2CH(CN)}Cp] (3a) and [Ni{Mes-NHC-(CH2)nCH(CN)}Cp] (3b-d; n = 2-4) were obtained.  All of these metallacycles contain Ni-C σ-bonds, and their synthesis generated a new asym. C center.  The cyclic complexes 3 were fully characterized by 1H and 13C NMR spectroscopy, IR spectroscopy and elemental analyses.  The structures of complexes 3b and 3d, which contain six- and eight-membered metallacyclic rings, resp., were detd. by single-crystal x-ray diffraction studies.  DFT studies, carried out to probe the mechanism of these cyclonickelation reactions, indicated that the mechanism of formation of these nickelacycles was similar to that obsd. for the formation of cyanomethyl ligands from coordinated MeCN.  Nevertheless, the base deprotonation of an α-C-H ligand in a side arm, while thermodynamically comparable to that of a simultaneously coordinated MeCN ligand, is kinetically favored, and this gives nickelacycles rather than cyanomethyl complexes in the case of the base-assisted activation of the cationic complexes 2.

Abstract: We report the first example of a structurally characterized oxyallyl −CH2C(O)CH2− group, trapped as a bridging ligand that spans two nickel centers. The ligand results from the double metalation of acetone on a nickel−NHC platform. A competing reaction leads to a single metalation of acetone.

Abstract: Cationic cyclopentadienyl mixed bis-N-heterocyclic carbene (NHC) nickel complexes of the general formula [Ni(NHC)(NHC′)Cp](PF6) (NHC/NHC′ = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene (Mes2NHC) a, 1,3-dimethyl-imidazol-2-ylidene (Me2NHC) b, 1-isopropyl-3-methyl-imidazol- 2-ylidene (iPr-NHC-Me) c; Cp = η5-C5H5) were prepared by the reaction of the cationic monocarbene complex [Ni(Mes2NHC)(NCMe)Cp](PF6) 1a or [Ni(Me2NHC)(NCMe)Cp](BF4) 1b with the appropriate free carbene. The new mixed bis(carbene) complexes [Ni(Mes2NHC)(Me2NHC)Cp](PF6) 2ab, [Ni(Mes2NHC)(iPr-NHC-Me)Cp](PF6) 2ac, and [Ni(Me2NHC)(iPr- NHC-Me)Cp](BF4) 2bc were obtained in moderate-to-high yields and were fully characterized by 1H and 13C NMR spectroscopies, elemental analyses, and, in the case of 2ab, by a single-crystal X-ray diffraction study. The monocarbene precursor 1b was also structurally characterized. The mixed bis-NHC complexes 2ab and 2ac were tested as catalysts for the Suzuki−Miyaura cross-coupling of phenylboronic acid with 4′-bromoacetophenone, and their activities were compared to that of related monocarbene CpNi complexes.

Abstract: The reactions of primary amines with the unsatd. heterodimetallic complex [(η-C5Me5)Ni(CO)3Mo(η-C5H5)] (1a) were studied.  Primary amines react with this heterodimetallic complex to form unstable adducts, which are in equil. with the free amine and complex 1a in soln.  Complex [(η-C5Me5)Ni(CO)3W(η-C5H5)] (1b), the Ni-W analog of 1a, reacts similarly with benzylamine.  The position of the equil. shifts in favor of the adducts at low temp., and crystals of the allylamine and benzylamine complexes [(η-C5Me5)(RNH2)Ni-Mo(CO)3(η-C5H5)], (2a, R = C3H5; 4a, R = PhCH2) could be isolated.  Their structures were established by single-crystal x-ray diffraction studies.  The primary amines in complexes 2a and 4a are each coordinated, by their resp. N atoms, to the Ni atom and thus provide the 1st structurally characterized examples of primary amine organometallic Ni complexes.  The bonding of the amine to the heterodimetallic center is in contrast to what was obsd. with P-contg. 2-electron donor ligands, in which the phosphine ligand is coordinated to the group 6 metal atom.  A measure of the enthalpy of the addn. reaction (ΔH°rxn) of benzylamine to 1b was obtained from a VT 1H NMR spectroscopic study and is -149 ± 10 kJ mol-1.  N-Bonded H atoms in both 2a and 4a exhibit intermol. H bonding interactions in the solid state with carbonyl O atoms of adjacent mols.  These mols. exist as loosely bound dimers in the solid state.  Complex 2a (C21H27MoNNiO3) crystallizes in the monoclinic space group P21/n with a 10.1922(2), b 11.1538(3), c 18.8053(4) Å, β 90.777(2)° and Z = 4.  Complex 4a (C25H29MoNNiO3) also crystallizes in the monoclinic space group P21/n with a 12.0840(4), b 10.9490(4), c 17.4930(6) Å, β 90.396(3)° and Z = 4.

Abstract: Ruthenacycles, which are easily prepd. in a single step by reaction between enantiopure arom. amines and [Ru(arene)Cl2]2 in the presence of NaOH and KPF6, are very good asym. transfer hydrogenation catalysts.  A range of arom. ketones were reduced using isopropanol in good yields with ee's up to 98%.  Iridacycles, which are prepd. in similar fashion from [IrCp*Cl2]2 are excellent catalysts for the racemization of secondary alcs. and chlorohydrins at room temp.  This allowed the development of a new dynamic kinetic resoln. of chlorohydrins to the enantiopure epoxides in up to 90% yield and 98% enantiomeric excess (ee) using a mutant of the enzyme Haloalc. dehalogenase C and an iridacycle as racemization catalyst.

Abstract: Nickel joins the fairly exclusive list of metals that can activate nitrile C-H bonds.  Authors report the first example of the C-H activation of an acetonitrile ligand on a nickel center.  The acetonitrile ligand formally loses a proton and undergoes a sharp flip to give a cyanomethyl ligand that is coordinated to the nickel atom.  Structures of an initial N-bound acetonitrile-nickel complex and of a final cyanomethyl-nickel complex are both presented.

Abstract: Cationic half-sandwich nickel complexes of general formula [Ni(NHC)(NCMe)(η5-C5R5)](PF6) [NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) a, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) b; R = H, Me] were prepd. from the reaction of their neutral homologues [Ni(NHC)Cl(η5-C5R5)] with 1 equiv. of KPF6 in acetonitrile at room temp. The new cationic complexes [Ni(IPr)(NCMe)(η5-C5Me5)](PF6) 3a, [Ni(IMes)(NCMe)(η5-C5Me5)](PF6) 3b and [Ni(IMes)(NCMe)(η5-C5H5)](PF6) 4b were obtained in high yield and were fully characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, elemental analyses, and in the case of 3a by a single-crystal x-ray diffraction study.  The neutral analog of 3a, [Ni(IPr)Cl(η5-C5Me5)] 1a was also structurally characterized.  Their geometries were compared and no significant structural differences were obsd.  Nevertheless soln. NMR spectroscopy established that the acetonitrile ligand of the cationic species is labile in soln.  This results in the absence of any rotational significant barrier about the nickel-carbene carbon bond at ambient temp. in soln. in the sterically congested cationic complexes 3a and 3b, in contrast to their neutral analogs 1a and [Ni(IMes)Cl(η5-C5Me5)] 1b.  The neutral and the cationic complexes catalyzed the cross-coupling of phenylboronic acid with aryl halides in the absence of co-catalysts or reductants.  Surprisingly, the neutral or cationic nature of the complexes proved to have almost no influence on the reaction yields and rates.  However, complexes bearing the bulky electron-rich pentamethylcyclopentadienyl ligand were much more active than those bearing the cyclopentadienyl ligand, and TOF of up to 190 h-1, a high rate for nickel(II) complexes under similar conditions, were obsd. with these species.

Abstract: series of N,N'-asym. substituted imidazolium iodide salts have been synthesized, starting from N-arylimidazoles and the less expensive, but less reactive, 1-chlorobutane or (3-chloropropyl)trimethoxysilane. The addn. of potassium iodide and the use of 1,2-dimethoxyethane as a solvent lead to multigram quantities of these salts becoming readily available, in yields ranging from 50% to 94%. Direct combination of (3-chloropropyl)trimethoxysilane with 1-mesityl-1H-imidazole was also effected, in good yield, by using a microwave oven at 180 °C. The synthesis of two 1-alkyl-3-isopropylimidazolium chlorides is also presented herein.

Abstract: A series of cationic half-sandwich ruthena- and iridacycle complexes were synthesized and shown to be highly active and efficient catalysts in the racemization of chiral alcs. and amines.  Upon activation with a base, these complexes are able to selectively racemize alcs., whereas the non-activated complexes are selective catalysts for the racemization of amines.  The iridacycles were further applied in the DKR of racemic β-chloroalcs. to produce chiral epoxides in a biphasic system in good yields and high ee.

Abstract: The article presents a four-part synthetic expt. that includes the synthesis of an imidazolium salt; the synthesis of [Ni(NH3)6] Cl2 and sodium cyclopentadienide; their reaction together to give nickelocene; and the reaction of the latter with the imidazolium salt to form the corresponding NHC-nickel(II) complex.  Each product can be characterized by either 1H NMR or IR spectroscopy, which allows the students to gain experience in these common characterization techniques.  These expts. have been successfully performed by fourth-year students (i.e., equiv. to fourth-year undergraduates in U.S. universities).

Abstract: The direct chemo-enzymic DKR of racemic β-haloalcs. is reported, yielding the corresponding optically active epoxides in a single step. The mutant haloalc. dehalogenase HheC Cys153Ser Trp249Phe is used for the asym. ring closure, whereas racemization of the remaining enantiomer of the haloalcohol is achieved using the new iridacycle I, one of the most effective racemization catalysts to date for β-haloalcohols.

Abstract: Neutral pentamethylcyclopentadienyl nickel half-sandwich imidazolylidene complexes [Cp*Ni(NHC)X] [Cp* = η5-C5Me5; NHC = 1,3-dimethyl-2-imidazolylidene (Me-NHC), 1,3-dimesityl-2-imidazolylidene (Mes-NHC), 1,3-bis(2,6-diisopropylphenyl)-2-imidazolylidene (iPr-NHC); X = Cl, I] were prepd. by ligand exchange of [Cp*Ni(acac)] with 1 equiv of the corresponding imidazolium salt (NHC·HX).  The new complexes [Cp*Ni(Me-NHC)I] (1a), [Cp*Ni(Mes-NHC)Cl] (2), and [Cp*Ni(iPr-NHC)Cl] (3) were obtained in moderate to good yields and were fully characterized by 13C and 1H NMR spectroscopy; 1a and 2 were characterized by single-crystal x-ray crystallog.  The related η5-cyclopentadienyl complex [CpNi(Me-NHC)I] (1b) was also synthesized and structurally characterized; its geometry and spectroscopic data are comparable to those of complex 1a.  The variable-temp. (VT) 1H NMR spectra of the sterically constrained complexes 2 and 3 are consistent with restricted rotation about the nickel-carbene carbon bond.  The free energy of activation for the dynamic processes, in both cases, was detd. to be on the order of 65-67 kJ mol-1 by VT NMR expts.

Abstract: The first examples of mixed metal trinuclear clusters carrying N-heterocyclic carbene (NHC) ligands, [(NHC)Ni(μ-CO)(μ3-CO)3(NiCp)(MoCp)] (3a,b; NHC = 1,3-Ar2-imidazol-2-ylidene, Ar = 2,6-iPr2C6H3, 2,4,6-Me2C6H2) were isolated from reactions of the complexes [Ni(NHC)ClCp] with [Mo(CO)3Cp]-; the unsatd. 46-electron clusters 3 have triangular MoNi2 cores and the reaction pathway activates usually inert Ni-Cp and Ni-NHC bonds.

Abstract: A review of hydrocarbyl ligand transformations, e.g., carbon-carbon and carbon-hydrogen bond formations and bond cleavage and rearrangement reactions on preformed heterobimetallic frameworks.

Abstract: The article presents three-step synthesis that allows the functionalization of an arom. amine by forming new C-C and C-N bonds via an intramol. C-H activation under mild conditions.  The reactions are stoichiometric and allow the students to isolate the different organometallic intermediates and, therefore, to have a better understanding of the global reaction pathway.  These expts. have been successfully performed by students in the second year of a joint masters degree in chem. and chem. engineering.  No specialized techniques or equipment are required apart from access to a nitrogen manifold and a vacuum pump.

Abstract: Ruthenacycles obtained by cyclometalation of enantiopure arom. primary or secondary amines with [(η6-benzene)RuCl2]2 or with [(η6-p-cymene)RuCl2]2 are efficient catalysts for asym. transfer hydrogenation (TOF up to 190 h-1 at room temp.).  Enantioselectivities in the transfer hydrogenation of acetophenone ranged from 38% to 89%.  It is possible to prep. the catalysts in situ, which allows the use of high throughput experimentation.

Abstract: Three new tetramines, (ArNHCH2CH2)3N, have been synthesized in which Ar = 3,5-(2,4,6-t-Bu3C6H2)2C6H3 (H3[HTBTN3N]), 3,5-(2,4,6-Me3C6H2)2C6H3 (H3[HMTN3N]), or 4-Br-3,5-(2,4,6-i-Pr3C6H2)2C6H2 (H3[pBrHIPTN3N]).  The diarylated tetramine, {3,5-(2,4,6-t-Bu3C6H2)2C6H3NHCH2CH2}2NCH2CH2NH2, has also been isolated, and the "hybrid" tetramine {3,5-(2,4,6-t-Bu3C6H2)2C6H3NHCH2CH2}2NCH2CH2NH(4-t-BuC6H4) has been prepd. from it.  Monochloride complexes, [(TerNCH2CH2)3N]MoCl, have been prepd., as well as a selection of intermediates that would be expected in a catalytic dinitrogen redn. such as [(TerNCH2CH2)3N]Mo≡N and {[(TerNCH2CH2)3N]Mo(NH3)}{BAr'4} (Ter = HTBT, HMT, or pBrHIPT and Ar' = 3,5-(CF3)2C6H3)).  Intermediates that contain the new terphenyl-substituted ligands are then evaluated for their efficiency for the catalytic redn. of dinitrogen under conditions where analogous [HIPTN3N]Mo species give four turnovers to ammonia under "std." conditions with an efficiency of ∼65%.  Only [pBrHIPTN3N]Mo compds. are efficient catalysts for dinitrogen redn.  The reasons are explored and discussed.

Abstract: Ethene was reacted under mild conditions with the benzene cycloruthenated dimethyl(phenylmethyl)amine compds. [Ru(η6-C6H6){2-(CH2NMe2-κN)-C6H4-κC1}L]+ (1a, L = Cl-; 1b, L = NCMe), obtained via intramol. C-H activation.  The stoichiometric arylated olefin dimethyl((2-ethenylphenyl)methyl)amine (2) and/or new organometallic species resulting from the overall insertion of one C atom into the Ru-C bond, [Ru(η6-C6H6){1-(CHMe-κC)-2-(CH2NMe2-κN)-C6H4}L]+ (3a, L = Cl-; 3b, L = NCMe), were obtained in varying proportions according to the reaction conditions and to the nature of the starting complex.  The six-membered metallacycles were found as a single racemic pair of enantiomers of RRuRC and SRuSC configurations, as established by 1H NOE expts.  In soln. under an Ar atm., 3a rearranged to the more stable five-membered ruthenacycle [Ru(η6-C6H6){2-(CH2NMe2-κN)-3-Et-C6H3-κC1}Cl] (4a).  Under ethene pressure, the intramol. rearrangement is followed by a 2nd ethene insertion into the Ru-C bond, giving [Ru(η6-C6H6){1-(CHMe-κC)-2-(CH2NMe2-κN)-3-Et-C6H3}Cl] (5a), the overall reaction being the result of a double C-H activation.  A mol. of propene also was inserted into the Ru-C bond of 1a.  Diastereo- and regiospecific double insertion giving [Ru(η6-C6H6){1-(CHEt-κC)-2-(CH2NMe2-κN)-3-iPr-C6H3}Cl] (7a) was obsd.  Ethene insertion performed on the benzene ruthenacycle 1a in deuterated MeOH led to stereospecific D incorporation in the six-membered metallacycle 3a at both C atoms of the CHMe unit.  These data militate in favor of the reversibility of most elementary steps of the insertion process.

Abstract: A review with 136 refs.

Abstract: The partial substitution of the MeCN ligand of compd. [(η6-C6H6)Ru(C6H4-2-CH2NMe2)(NCMe)]+ PF6- (1a) by CD3OD was obsd. while running the 1H NMR spectra of 1a in this solvent, this giving 1b.  In opposition to 1a, the 1H NMR spectrum of 1b is temp.-dependent, as at T > 40° the coalescence of the signals of the -CH2NMe2 protons was obsd., this being an evidence for the fast racemization of the Ru center in 1b at the NMR timescale.  DFT calcns. help to suggest a likely process for this racemization.  It should take place via the decoordination of the MeOH ligand at an early step of the reaction, followed by the inversion of the configuration of the thus-obtained 16 e- species (2).  The transition state (3) for this latter reaction was identified and the total free energy of the racemization was thus calcd., affording a value close to the activation energy found exptl. by 1H NMR (∼13 kcal mol-1 vs. ∼15.5 kcal mol-1, resp.).

Abstract: Bulk solid samples of various ratios of the cyclometalated arene Ru diastereomers (S)Ru- and (R)Ru-[(η6-C6H6)Ru(C6H4-2-(R)-CH(Me)NMe2)PMe2Ph]+PF6- (3a/3b), of which the configurational stability at the metal center was established by classical soln. techniques, were analyzed by 13C CPMAS (CP-MAS) and 31P MAS NMR.  The spectra obtained allowed the authors to detect both isomers and to est. their resp. proportions by 31P spectra.  This technique was applied to a bulk solid sample of the diastereomers (S)Ru- and (R)Ru-[(η6-C6H6)Ru(C6H4-2-(R)-CH(Me)NMe2)NCMe]+PF6- (1a/1b), which are configurationally labile by classical soln. expts.  Detection of isomer 1a only in the resulting 13C CP-MAS NMR spectrum demonstrated that there was epimerization of 1b to 1a during crystn., thus confirming the configurational lability at the metal center.  The crystal and molecular structures of 3a were detd. by x-ray crystallography.

Abstract: The reaction between cycloruthenated N,N-dimethylbenzylamine [(η6-C6H6)Ru(C6H4CH2NMe2)Cl] and ethylene under very mild conditions afforded 81% 2-vinyl-N,N-dimethylbenzylamine and an organometallic Ru derivative resulting from the overall insertion of one C atom in the Ru-C bond of the starting material.

Abstract: Cycloruthenated complexes [(η6-C6H6)Ru(L)CH3CN]+PF6- (L = C6H4-2-CH2NMe2, (R)-(+)-C6H4-2-CH(Me)NMe2, C6H2-3,4-(OCH3)2-2-CH2NMe2) are readily obtained by the intramolecular C-H activation of N,N-dimethylbenzylamine derivs. with [(η6-C6H6)RuCl2]2 in MeCN in up to 53% isolated yields.  Under similar conditions, 8-methylquinoline also led to a cycloruthenated complex, though in lower yield (12%) and after a longer reaction time.  Reaction with the optically active (R)-(+)-N,N-dimethyl-1-phenylethylamine led to a 48% diastereomeric excess in the cycloruthenated product.  Under the same conditions, and after 14 and 65 h of reaction time, resp., 2-phenyl- and 2-benzylpyridine are cyclometalated, giving complexes in which the benzene ligand is substituted by three acetonitriles: [(L)Ru(MeCN)4]+PF6- (L = C6H4-2-C5H4N, C6H4-2-(CH2)-C5H4N) were obtained in 40 and 24% isolated yields, respectively.

Abstract: The invention relates to an enantiomerically enriched chiral compd. comprising a transition metal M, which comprises four, five or six coordinating groups of which at least one pair is linked together to form a bidentate ligand, in which M is directly bound via one single σ-bond to a carbon atom of an optionally substituted and/or optionally fused (hetero)arom. ring of said bidentate ligand and in which M is directly bound to a nitrogen atom of a primary or secondary amino group of said bidentate ligand, thereby forming a metalacycle between said bidentate ligand and the metal M, said metal M being selected from the metals of groups 8 and 9 of the Periodic Table of the Elements, in particular iron, ruthenium, osmium, cobalt, rhodium, or iridium.  The chiral compd. can be used as a catalyst, preferably in an asym. transfer hydrogenation process.  The invention further relates to a process for an asym. transfer hydrogenation of a prochiral compd. in the presence of a hydrogen donor and the chiral compd. of the invention comprising a transition metal chosen from the metals of groups 8, 9 and 10 of the Periodic Table, in particular iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium or platinum as the catalyst.  Thus, reaction of [Ru(η6-C6H6)Cl2]2 with (S)-1-aminotetralin in the presence of NaOH/KPF6 in MeCN for 72 h at 20° gave title catalyst (S)-[Ru(η6-C6H6){3-(NH2κN)-C10H10-κC1}(NCMe)(KPF6)] which was used for asym. transfer hydrogenation of acetophenone.