Iron carbonyl complexes with chiral, bidentate biphosphine ligands

Abstract

The present invention relates to iron carbonyl complexes of the general formula LFe(CO)3 (I), wherein L is a chiral, bidentate biphosphine ligand, to processes for preparing them and to their use as catalysts for hydrogenating olefins, for example alkyl-substituted olefins, or prochiral α,β-unsaturated aldehydes or ketones, with hydrogen.

Description

[0001] Iron carbonyl complexes with chiral, bidentate biphosphine ligands

[0002] Description

[0003] The present invention relates to iron carbonyl complexes of the general formula LFe(CO)3(I) with chiral, bidentate biphosphine ligands, processes for their preparation and their use as catalysts for the hydrogenation of olefins, such as alkyl-substituted olefins or prochiral α,β-unsaturated aldehydes or ketones, with hydrogen.

[0004] State of the art

[0005] Olefins can be hydrogenated using a variety of homogeneous catalysts using hydrogen. Rhodium-, iridium-, or ruthenium-based transition metal complexes are commonly used as noble metal catalysts (see, for example, Blaser et al. in Applied Homogeneous Catalysis with Organometallic Compounds, editors B. Cornils, W.A. Herrmann, M. Beller, R. Paciello, Wiley-VCH, New York, Vol. 3, 2018, pp. 621-690).

[0006] With the aim of finding replacements for the precious metal catalysts mentioned above, attempts are being made to enable hydrogenation with iron-based catalysts (see, for example, Langer et al. in Homogeneous Hydrogenation with Non-Precious Catalysts, Editor JF Teichert, Wiley-VCH, New York, 2020, 15-38).

[0007] J. Angelici et al., J. Am. Chem. Soc., 1992, 114, 160-165, describe the preparation of tricarbonyl iron complexes with dppe, dppp, and other bidentate phosphine ligands. No application of these compounds as catalysts is described. Compounds of the type (L)Fe(CO)3 (L = bidentate biphosphine ligand) exhibit stable 18-electron complex coordination (C. Elschenbroich, A. Salzer in Organometallic Chemistry, Teubner Taschenbücher Chemie, Wiesbaden, 1990). For catalytic activity, at least one CO must be able to be eliminated under reaction conditions.

[0008] P.-J. Chirik et al., Organometallics, 2014, 33, 5781-5790, describe a process for the homogeneous catalysis of olefins using iron-based catalysts. Carbonyl-free iron compounds are used as catalysts, which are very complex to synthesize.

[0009] P. Casey et al., Israel Journal of Chemistry 30, 1990, 299-304, concerns theoretical calculations on the "natural bite angle" of diphosphine chelate ligands. Among other things, an iron carbonyl complex [1] with ligand [2] is described: To date, the use of iron tricarbonyl complexes or iron dicarbonyl complexes with bidentate phosphine ligands as catalysts has not been described.

[0010] It has surprisingly been found that iron carbonyl complexes of general formula (I), which contain chiral, bidentate biphosphine ligands, can be used as hydrogenation catalysts and represent a cost-effective alternative to noble metal catalysts. The iron carbonyl complexes of general formula (I) can be characterized by high activity, high product selectivity, and / or high conversion rates. When prochiral substrates are used, the iron carbonyl complexes of general formula (I) can deliver high enantioselectivities. A further advantage of the iron carbonyl complexes of general formula (I) is the cost-effective disposal of catalyst residues.

[0011] The present invention relates to iron carbonyl complexes of the general formula LFe(CO)3(I), where

[0012] L represents a chiral, bidentate bisphosphine ligand, which is preferably selected from compounds of the formula their enantiomers, where

[0013] R 1 and R 2 each independently of one another represents an unbranched, branched or cyclic hydrocarbon radical having 1 to 20 carbon atoms, which is saturated or may have one or more, generally 1 to about 4, non-conjugated, ethylenic double bonds and which is unsubstituted or carries one or more, generally 1 to 4, identical or different substituents selected from OR 9 , NR 10 R 11 , halogen, C6-C 10 -aryl and C3-C9-hetaryl, or

[0014] R 1 and R 2 together may also represent a 2 to 10-membered alkylene group or a 3 to 10-membered cycloalkylene group, in which 1, 2, 3 or 4 non-adjacent CH2 groups are replaced by O or NR 9cmay be replaced, wherein the alkylene group and the cycloalkylene group are saturated or have one or two non-conjugated ethylenic double bonds, and wherein the alkylene group and the cycloalkylene group are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl;

[0015] R 3 and R 4 each independently represents hydrogen or straight-chain or branched C1-C4 alkyl and

[0016] R 5 , R 6 , R 7 and R 8 are the same or different and for C6-C 10 -aryl which is unsubstituted or carries one or more substituents selected from C1-C6 alkyl, C3-C6 cycloalkyl, C6-C 10 -Aryl, C1-C6 alkoxy and amino;

[0017] R 9c for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12-alkylaryl, R 9 , R 10 and R 11 each independently hydrogen, C1-C4 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, where

[0018] R 10 and R 11 together may also represent an alkylene chain with 2 to 5 carbon atoms, which may be interrupted by N or O.

[0019] Furthermore, the present invention relates

[0020] - a process for the preparation of an iron carbonyl complex of the general formula (I), comprising the reaction of a chiral, bidentate bisphosphine ligand L, which is preferably selected from compounds of the formula and their enantiomers, with an iron precursor compound, where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 have the meaning given above;

[0021] - Use of an iron carbonyl complex of the general formula (I) or of an iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO (I 1 ) or LFeCO2(I"), as a precatalyst or catalyst, in particular for the preparation of an organic compound by hydrogenation of an unsaturated organic compound with hydrogen; and

[0022] - a process for preparing an organic compound by hydrogenating an unsaturated organic compound with hydrogen in the presence of at least one iron carbonyl complex of the general formula (I) or an iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO (I') or LFeCO2(I").

[0023] In a further preferred embodiment of the present invention, the iron carbonyl complex of the general formula (I) or the iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO (I') or LFeCO2(I"), is used to prepare an optically active compound by asymmetric hydrogenation of a prochiral, unsaturated compound with hydrogen.

[0024] Suitable chiral bidentate bisphosphine ligands for the purposes of the present invention are compounds such as those described, for example, in: I. Ojima (ed.), Catalytic Asymmetry Synthesis, Wiley-VCh, 2nd edition, 2000 or in EN Jacobsen, A. Pfaltz, H. Yamamoto (ed.), Comprehensive Asymmetry Catalysis, 2000, Springer or in W. Tang, X. Zhang, Chem. Rev. 2003, 103, 3029-3069. The following compounds are exemplified as chiral ligands (1) to (91) and their enantiomers that can be used with preference according to the invention:

[0025]

[0026] In formulas (1) to (91), "Ph" means phenyl, "Cy" means cyclohexyl, "Xyl" means xylyl, "Tol" means p-tolyl and "Bn" means benzyl.

[0027] Among the chiral ligands mentioned above, those falling under the general formulas (II), (III), or (IV) are preferred. Those falling under the general formula (II) are particularly preferred.

[0028] Particularly preferred chiral, bidentate bisphosphine ligands are those of the general formulas or

[0029] enantiomers, where

[0030] R 1 and R 2each independently of one another represents an unbranched, branched or cyclic hydrocarbon radical having 1 to 20 carbon atoms, which is saturated or may have one or more, generally 1 to about 4, non-conjugated, ethylenic double bonds and which is unsubstituted or carries one or more, generally 1 to 4, identical or different substituents selected from OR 9 , NR 10 R 11 , halogen, C6-C 10 -aryl and C3-C9-hetaryl, or

[0031] R 1 and R 2 together may also represent a 2 to 10-membered alkylene group or a 3 to 10-membered cycloalkylene group, in which 1, 2, 3 or 4 non-adjacent CH2 groups are replaced by O or NR 9cmay be replaced, wherein the alkylene group and the cycloalkylene group are saturated or have one or two non-conjugated ethylenic double bonds, and wherein the alkylene group and the cycloalkylene group are unsubstituted or carry one or more identical or different substituents selected from C1-C4-alkyl; R 3 and R 4 each independently represents hydrogen or straight-chain or branched C1-C4 alkyl and R 5 , R 6 , R 7 and R 8 are the same or different and for C6-C 10 -aryl which is unsubstituted or carries one or more substituents selected from C1-C6 alkyl, C3-C6 cycloalkyl, C6-C 10 -Aryl, C1-C6 alkoxy and amino; R 9c for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, R 9 , R 10 and R 11each independently hydrogen, C1-C4 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, where R 10 and R 11 together may also represent an alkylene chain having 2 to 5 carbon atoms, which may be interrupted by N or O. With regard to formulas (II), (III) and (IV), the variables have in particular the following meaning: R 1 and R 2 each independently represents an unbranched, branched or C1-C4 alkyl radical or R 1 and R 2 together or represent a C3-C7 alkanediyl radical, C3-C7 alkenediyl radical, C5-C7 cycloalkanediyl radical or a C5-C7 cycloalkenediyl radical, where the four aforementioned radicals are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl; R 3 and R 4each independently represents hydrogen or straight-chain or branched C1-C4 alkyl and R 5 , R 6 , R 7 and R 8 represent phenyl. According to the invention, particularly preferred chiral, bidentate bisphosphine ligands are those of the general formula (II), in particular the compound of the formula (1) or the formulas (IIa) or (IIb), hereinafter referred to as "Chiraphos", and the compound of formulas (IId) or (IIc) designated as "Norphos", and the compound designated as DIOP of formula (4) or formulas (IIe) or (IIf), and the compound of formula (91) or formulas (IIg) or (IIh), where Ph is phenyl and Bn is benzyl. Most preferably, the chiral, bidentate bisphosphine ligand is either a compound of the formula or the formula ( ) where Ph stands for phenyl. According to the invention, the selected chiral ligands are each used in the form of one of their two enantiomers. The chiral ligands typically have an enantiomeric excess (ee) of at least 80% ee, in particular at least 90% ee, and especially at least 95% ee. In the definitions of the variables given in the above and following formulas, collective terms are used that are generally representative of the respective substituents. The meaning of C n -C m- indicates the possible number of carbon atoms in the respective substituent or substituent part. For the purposes of the present invention, the term "alkyl" encompasses unbranched or branched alkyl groups having 1 to 4, 6, 12, or 25 carbon atoms. These include, for example, C1-C6 alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-Ethylpropyl, n-Hexyl, 2-Hexyl, 2-Methylpentyl, 3-Methylpentyl, 4-Methylpentyl, 1,2-Dimethylbutyl, 1,3-Dimethylbutyl, 2,3-Dimethylbutyl, 1,1-Dimethylbutyl, 2,2-Dimethylbutyl, 3,3-Dimethylbutyl, 1,1,2-Trimethylpropyl, 1,2,2-Trimethylpropyl, 1-Ethylbutyl, 2-Ethylbutyl, 1-Ethyl-2-methylpropyl and the like. "Alkyl" preferably refers to unbranched or branched C1-C6 alkyl groups.In the context of the present invention, the term "cycloalkyl" encompasses cyclic, saturated hydrocarbon groups having 3 to 6, 12 or 25 carbon ring members, e.g. C3-C8 cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, or C7-C. 12-Bicycloalkyl. In the context of the present invention, the term "alkoxy" stands for an alkyl group bonded via an oxygen atom having 1 to 6 C atoms, e.g. C1-C6-alkoxy, such as methoxy, ethoxy, n-propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methylpropoxy, 1,1-dimethylethoxy, pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy, 1-ethylpropoxy, hexoxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-Dimethylbutoxy, 3,3-Dimethylbutoxy, 1-Ethylbutoxy, 2-Ethylbutoxy, 1,1,2-Trimethylpropoxy, 1,2,2-Trimethylpropoxy, 1-Ethyl-1-methylpropoxy or 1-Ethyl-2-methylpropoxy. "Alkoxy" is preferably C1-C4-alkoxy. In the context of the present invention, the term "alkenyl" encompasses unbranched or branched hydrocarbon radicals having 2 to 4, 6, 12 or 25 C atoms, which contain at least one double bond,beispielsweise 1, 2, 3, oder 4 Doppelbindungen enthalten. Dazu zählen beispielsweise C2-C6-Alkenyl wie Ethenyl, 1-Propenyl, 2-Propenyl, 1-Methylethenyl, 1-Butenyl, 2-Butenyl, 3-Butenyl, 1-Methyl-1-propenyl, 2-Methyl-1-propenyl, 1-Methyl-2-propenyl, 2-Methyl-2-propenyl, 1-Pentenyl, 2-Pentenyl, 3-Pentenyl, 4-Pentenyl, 1-Methyl-1-butenyl, 2-Methyl-1-butenyl, 3-Methyl-1-butenyl, 1-Methyl-2-butenyl, 2-Methyl-2-butenyl, 3-Methyl-2-butenyl, 1-Methyl-3-butenyl, 2-Methyl-3-butenyl, 3-Methyl-3-butenyl, 1,1-Dimethyl-2-propenyl, 1,2-Dimethyl-1-propenyl, 1,2-Dimethyl-2-propenyl, 1-Ethyl-1propenyl, 1-Ethyl-2-propenyl, 1-Hexenyl, 2-Hexenyl, 3- Hexenyl, 4-Hexenyl, 5-Hexenyl, 1-Methyl-1-pentenyl, 2-Methyl-1-pentenyl, 3-Methyl-1- pentenyl, 4-Methyl-1-pentenyl, 1-Methyl-2-pentenyl, 2-Methyl-2-pentenyl, 3-Methyl-2- pentenyl, 4-Methyl-2-pentenyl, 1-Methyl-3-pentenyl, 2-Methyl-3pentenyl, 3-Methyl-3- pentenyl, 4-Methyl-3-pentenyl, 1-Methyl-4-pentenyl, 2-Methyl-4-pentenyl, 3-Methyl-4- pentenyl,4-Methyl-4-pentenyl, 1,1-Dimethyl-2-butenyl, 1,1-Dimethyl-3-butenyl, 1,2-Dimethyl-1-butenyl, 1,2-Dimethyl-2-butenyl, 1,2-Dimethyl-3- butenyl, 1,3-Dimethyl-1-butenyl, 1,3-Dimethyl-2-butenyl, 1,3-Dimethyl-3-butenyl, 2,2-Dimethyl-3-butenyl, 2,3-Dimethyl-1-butenyl, 2,3-Dimethyl-2-butenyl, 2,3-Dimethyl-3- butenyl, 3,3-Dimethyl-1-butenyl, 3,3-Dimethyl-2-butenyl, 1-Ethyl-1-butenyl, 1-Ethyl-2-butenyl, 1-Ethyl-3-butenyl, 2-Ethyl-1-butenyl, 2-Ethyl-2-butenyl, 2-Ethyl-3-butenyl, 1,1,2-Trimethyl-2- propenyl, 1-Ethyl-1-methyl-2-propenyl, 1-Ethyl-2-methyl-1-propenyl und 1-Ethyl-2-methyl-2- propenyl. Bevorzugt handelt es sich bei "Alkenyl" um unverzweigte C2-C, 12 -Alkenylgruppen oder verzweigte C3-C 12-Alkenyl groups each having 1 to 3 double bonds, particularly preferably unbranched C2-C6 alkenyl groups or branched C3-C6 alkenyl groups each having one double bond. In the context of the present invention, the term "alkylene" refers to divalent hydrocarbon radicals having 2 to 25 carbon atoms. The divalent hydrocarbon radicals can be unbranched or branched. These include, for example, C2-C 16-Alkylene groups, such as 1,4-butylene, 1,5-pentylene, 2-methyl-1,4-butylene, 1,6-hexylene, 2-methyl-1,5-pentylene, 3-methyl-1,5-pentylene, 1,7-heptylene, 2-methyl-1,6-hexylene, 3-Methyl-1,6-hexylene, 2-Ethyl-1,5-pentylene, 3-Ethyl-1,5-pentylene, 2,3-Dimethyl-1,5-pentylene, 2,4-Dimethyl-1,5-pentylene, 1,8-Octylene, 2-Methyl-1,7-heptylene, 3-Methyl-1,7-heptylene, 4-methyl-1,7-heptylene, 2-Ethyl-1,6-hexylene, 3-Ethyl-1,6-hexylene, 2,3-Dimethyl-1,6-hexylene, 2,4-Dimethyl-1,6-hexylene, 1,9-Nonylene, 2-Methyl-1,8-Octylene, 3-Methyl-1,8-Octylene, 4-methyl-1,8-octylene, 2-ethyl-1,7-heptylene, 3-ethyl-1,7-heptylene, 1,10-decylene, 2-methyl-1,9-nonylene, 3-methyl-1,9-nonylene, 4-methyl-1,9-nonylene, 5-methyl-1,9-nonylene, 1,11-undecylene, 2-methyl-1,10-decylene, 3-methyl-1,10-decylene, 5-methyl-1,10-decylene, 1,12-dodecylene, 1,13-tridecylene, 1,14-tetradecylene, 1,15-pentadecylene, 1,16-hexadecylene, and the like. "Alkylene" is preferably unbranched C2-C 12 -alkylene groups or branched C3-C12Alkylene groups, in particular unbranched C2-C6 alkylene groups or branched C3-C6 alkylene groups. In the singly or multiply branched alkylene groups, the carbon atom at the branching point or the carbon atoms at the respective branching points can, independently of one another, have an R or an S configuration, or both configurations in equal or different proportions. In the context of the present invention, the term "alkenylene" refers to divalent hydrocarbon radicals having 2 to 25 carbon atoms, which can be unbranched or branched, wherein the main chain has one or more double bonds, for example 1, 2, or 3 double bonds. These include, for example, C2-C18 alkenylene groups such as ethylene, propylene, 1-, 2-butylene, 1-, 2-pentylene, 1-, 2-, 3-hexylene, 1,3-hexadienylene, 1,4-hexadienylene, 1-, 2-, 3-heptylene, 1,3-heptadienylene, 1,4-heptadienylene, 2,4-heptadienylene, 1-, 2-, 3-octenylene, 1,3-octadienylene, 1,4-Octadienylen, 2,4-Octadienylen, 1-, 2-, 3-Nonenylen, 1-, 2-, 3-, 4-, 5-Decenylen, 1-, 2-, 3-, 4-, 5- Undecenylen, 2-, 3-, 4-, 5-, 6-Dodecenylen, 2,4-Dodecadienylen, 2,5-Dodecadienylen, 2,6- Dodecadienylen, 3-, 4-, 5-, 6-Tridecenylen, 2,5-Tridecadienylen, 4,7-Tridecadienylen, 5,8- Tridecadienylen, 4-, 5-, 6-, 7-Tetradecenylen, 2,5-Tetradecadienylen, 4,7-Tetradecadienylen, 5,8-Tetradecadienylen, 4-, 5-, 6-, 7-Pentadecenylen, 2,5-Pentadecadienylen, 4,7- Pentadecadienylen, 5,8-Pentadecadienylen, 1,4,7-Pentadecatrienylen, 4,7,11- Pentadecatrienylen, 4,6,8-Pentadecatrienylen, 4-, 5-, 6-, 7-, 8-Hexadecenylen, 2,5- Hexadecadienylen, 4,7-Hexadecadienylen, 5,8-Hexadecadienylen, 2,5,8-Hexadecatrienylen, 4,8,11-Hexadecatrienylen, 5,7,9-Hexadecatrienylen, 5-, 6-, 7-, 8-Heptadecenylen, 2,5- Heptadecadienylen, 4,7-Heptadecadienylen, 5,8-Heptadecadienylen, 5-, 6-, 7-, 8-, 9- Octadecenylen, 2,5-Octadecadienylen, 4,7-Octadecadienylen, 5,8-octadecadienylene and the like. "Alkenylene" is preferably unbranched C3-C, 12 - Alkenylene groups or branched C4-C 12 -Alkenylene groups each having one or two double bonds, in particular unbranched C3-C8 alkenylene groups having one double bond. The double bonds in the alkenylene groups can be present independently of one another in the E or Z configuration or as a mixture of both configurations. In the context of the present invention, the term "halogen" encompasses fluorine, chlorine, bromine and iodine, preferably fluorine, chlorine or bromine. In the context of the present invention, the term "aryl" encompasses one to trinuclear aromatic ring systems containing 6 to 14 carbon ring members. These include, for example, C6-C 10-aryl, such as phenyl or naphthyl. In the context of the present invention, the term "hetaryl" encompasses a trinuclear aromatic ring system containing 6 to 14 carbon ring members, wherein one or more, for example 1, 2, 3, 4, 5, or 6, carbon atoms are substituted by a nitrogen, oxygen, and / or sulfur atom.Dazu zählen beispielsweise C3-C9- Hetarylgruppen, wie 2-Furyl, 3-Furyl, 2-Thienyl, 3-Thienyl, 2-Pyrrolyl, 3-Pyrrolyl, 3-Isoxazolyl, 4-Isoxazolyl, 5-Isoxazolyl, 3-Isothiazolyl, 4-Isothiazolyl, 5-Isothiazolyl, 3-Pyrazolyl, 4-Pyrazolyl, 5-Pyrazolyl, 2-Oxazolyl, 4-Oxazolyl, 5-Oxazolyl, 2- Thiazolyl, 4-Thiazolyl, 5-Thiazolyl, 2-Imidazolyl, 4-Imidazolyl, 1,2,4-Oxadiazol-3-yl, 1,2,4- Oxadiazol-5-yl, 1,2,4-Thiadiazol-3-yl, 1,2,4-Thiadiazol-5-yl, 1,2,4-Triazol-3-yl, 1,3,4- Oxadiazol-2-yl, 1,3,4-Thiadiazol-2-yl, 1,3,4-Triazol-2-yl, 2-Pyridinyl, 3-Pyridinyl, 4-Pyridinyl, 3-Pyridazinyl, 4-Pyridazinyl, 2-Pyrimidinyl, 4-Pyrimidinyl, 5-Pyrimidinyl, 2-Pyrazinyl, 1,3,5-Triazin-2-yl, 1,2,4-Triazin-3-yl, 2-Indolyl, 3-Indolyl, 4-Indolyl, 5-Indolyl, 6-Indolyl, 7-Indolyl und dergleichen. Bevorzugt handelt es sich bei "Hetaryl" um C5- C6-Hetaryl.For the purposes of the present invention, the term "aralkyl" encompasses a mono- to dinuclear aromatic ring system containing 6 to 10 carbon ring members, bonded via an unbranched or branched C1-C6 alkyl group. These include, for example, C7-C. 12 -Aralkyl, such as phenylmethyl, 1-phenylethyl, 2-phenylethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl and the like. In the context of the present invention, the term "aralkyl" encompasses one to binuclear aromatic ring systems containing 6 to 10 carbon ring members, which are substituted by one or more, for example 1, 2 or 3, unbranched or branched C1-C6-alkyl radicals. These include, for example, C7-C 12-Alkylaryl, wie 1-Methylphenyl, 2-Methylphenyl, 3-Methylphenyl, 1-Ethylphenyl, 2-Ethylphenyl, 3- Ethylphenyl, 1-Propylphenyl, 2-Propylphenyl, 3-Propylphenyl, 1-iso-Propylphenyl, 2-iso- Propylphenyl, 3-iso-Propylphenyl, 1-Butylphenyl, 2-Butylphenyl, 3-Butylphenyl, 1-iso- Butylphenyl, 2-iso-Butylphenyl, 3-iso-Butylphenyl, 1-sec-Butylphenyl, 2-sec-Butylphenyl, 3- sec-Butylphenyl, 1-tert-Butylphenyl, 2-tert-Butylphenyl, 3-tert-Butylphenyl, 1-(1- pentenyl)phenyl, 2-(1-pentenyl)phenyl, 3-(1-pentenyl)phenyl, 1-(2-pentenyl)phenyl, 2-(2- pentenyl)phenyl, 3-(2-pentenyl)phenyl, 1-(3-pentenyl)phenyl, 2-(3-pentenyl)phenyl, 3-(3- pentenyl)phenyl, 1-(1-(2-methylbutyl))phenyl, 2-(1-(2-methylbutyl))phenyl, 3-(1-(2- methylbutyl))phenyl, 1-(2-(2-methylbutyl))phenyl, 2-(2-(2-methylbutyl))phenyl, 3-(2-(2- methylbutyl))phenyl, 1-(3-(2-methylbutyl))phenyl, 2-(3-(2-methylbutyl))phenyl, 3-(3-(2- methylbutyl))phenyl, 1-(4-(2-methylbutyl))phenyl, 2-(4-(2-methylbutyl))phenyl, 3-(4-(2- methylbutyl))phenyl, 1-(1-(2,2-Dimethylpropyl))phenyl, 2-(1-(2,2-Dimethylpropyl))phenyl, 3- (1-(2,2-Dimethylpropyl))phenyl, 1-(1-hexenyl)phenyl, 2-(1-hexenyl)phenyl, 3-(1- hexenyl)phenyl, 1-(2-hexenyl)phenyl, 2-(2-hexenyl)phenyl, 3-(2-hexenyl)phenyl, 1-(3- hexenyl)phenyl, 2-(3-hexenyl)phenyl, 3-(3-hexenyl)phenyl, 1-(1-(2-Methylpentenyl))phenyl, 2- (1-(2-Methylpentenyl))phenyl, 3-(1-(2-Methylpentenyl))phenyl, 1-(2-(2- Methylpentenyl))phenyl, 2-(2-(2-Methylpentenyl))phenyl, 3-(2-(2-Methylpentenyl))phenyl, 1- (3-(2-Methylpentenyl))phenyl, 2-(3-(2-Methylpentenyl))phenyl, 3-(3-(2- Methylpentenyl))phenyl, 1-(4-(2-Methylpentenyl))phenyl, 2-(4-(2-Methylpentenyl))phenyl, 3- (4-(2-Methylpentenyl))phenyl, 1-(5-(2-Methylpentenyl))phenyl, 2-(5-(2- Methylpentenyl))phenyl, 3-(5-(2-Methylpentenyl))phenyl, 1-(1-(2,2-Dimethylbutenyl))phenyl, 2-(1-(2,2-Dimethylbutenyl))phenyl, 3-(1-(2,2-Dimethylbutenyl))phenyl, 1-(3-(2,2- Dimethylbutenyl))phenyl, 2-(3-(2,2-Dimethylbutenyl))phenyl, 3-(3-(2,2- Dimethylbutenyl))phenyl, 1-(4-(2,2-Dimethylbutenyl))phenyl, 2-(4-(2,2-Dimethylbutenyl))phenyl, 3-(4-(2,2-Dimethylbutenyl))phenyl and the like.

[0032] In a preferred embodiment, the present invention relates to iron carbonyl complexes of the general formula LFe(CO)3(I), where

[0033] L represents a chiral, bidentate bisphosphine ligand selected from

[0034] Compounds of the formula

[0035] enantiomers, where

[0036] R 1 and R 2 each independently represents an unbranched, branched or C1-C4-alkyl radical or

[0037] R 1 and R 2together or represent a C3-C7 alkanediyl radical, C3-C7 alkenediyl radical, C5-C7 cycloalkanediyl radical or a C5-C7 cycloalkenediyl radical, where the four aforementioned radicals are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl;

[0038] R 3 and R 4 each independently represents hydrogen or straight-chain or branched C1-C4 alkyl and

[0039] R 5 , R 6 , R 7 and R 8 stand for phenyl.

[0040] In this embodiment, the chiral, bidentate bisphosphine ligand L is particularly preferably a compound of the general formula (II). Particularly preferred iron complexes of the general formula LFe(CO)3(I) are listed in the table below: The most preferred iron complexes are A-1 and A-2. The iron carbonyl complex A-1, (Fe(CO)3(R,R-Chiraphos), crystallizes in an orthorhombic unit cell, space group P212121. Fig. 1 shows the asymmetric unit of the crystal structure of Fe(CO)3(R,R-Chiraphos). Fig. 2 shows the crystal structure of Fe(CO)3(R,R-Chiraphos). The iron complex exhibits axial-equatorial coordination of R,R-Chiraphos to the central atom. The present invention also relates to the use of the above-described iron carbonyl complexes of the general formula (I) as catalysts, in particular the use of the iron carbonyl complexes of the general formula (I) for the preparation of an organic compound by hydrogenation of an unsaturated organic compound, such as an unsaturated carbonyl compound, an alkene, or imine.with hydrogen. The iron carbonyl complex can advantageously be used to prepare an optically active compound by asymmetric hydrogenation of a prochiral, unsaturated compound with hydrogen. The present invention is also directed to processes for preparing a compound by hydrogenation of an unsaturated compound with hydrogen in the presence of at least one iron carbonyl complex of the general formula (I). In an advantageous embodiment of the present invention, the process according to the invention has at least one or all of the following features a - h: a) carrying out the hydrogenation at a hydrogen pressure of 5 to 200 bar, in particular at a hydrogen pressure of 10 to 100 bar; b) carrying out the process batchwise or continuously; c) in-situ generation of the iron carbonyl complex before or during the hydrogenation by reacting an achiral iron precursor compound with a chiral,bidentate bisphosphine ligand L and optionally CO; d) pretreating the catalyst prior to hydrogenation with a gas mixture containing carbon monoxide or carbon monoxide / hydrogen; e) carrying out the hydrogenation in the presence of carbon monoxide additionally added to the reaction mixture; f) carrying out the hydrogenation with hydrogen having a carbon monoxide content in the range from 50 to 3000 ppm, in particular in the range from 100 to 2000 ppm; g) carrying out the hydrogenation in a gas circulation reactor; h) carrying out the hydrogenation in a gas circulation reactor, wherein the unsaturated compound and the hydrogen are introduced into the gas circulation reactor by means of a two-fluid nozzle. The unsaturated organic compound is preferably a doubly or trisubstituted, prochiral or non-prochiral, unsaturated organic compound, in particular a prochiral or non-prochiral, unsaturated carbonyl compound.in particular a prochiral or non-prochiral, α,β-unsaturated ketone or a prochiral or non-prochiral α,β-unsaturated aldehyde. Examples of preferred unsaturated organic compounds are compounds of the general formula, , where R 12 and R 13 are the same or different from each other and each represents hydrogen, C6-C 10 - aryl, C3-C9-hetaryl, an unbranched, branched or cyclic hydrocarbon radical having 1 to 25 carbon atoms, which is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and which is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10 -aryl and C3-C9-hetaryl; R 12 together with R 13 or R 15forms an optionally substituted 5- or 6-membered ring; R 13 together with R 12 or R 15 forms an optionally substituted 5- or 6-membered ring; R 14 represents hydrogen, C1-C6-alkoxy or an unbranched, branched or cyclic hydrocarbon radical having 1 to 25 carbon atoms, which is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and which is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10 -Aryl and C3-C9-Hetaryl; or R 14 together with one of the residues R 12 or R 13 may also be a 3 to 25-membered alkylene group, in which 1, 2, 3 or 4 non-adjacent CH2 groups are replaced by O or NR 16cmay be replaced, wherein the alkylene group is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and wherein the alkylene group is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C1-C4 alkyl, C6-C 10 -aryl and C3-C9-hetaryl, where two substituents can also together represent a 2 to 10-membered alkylene group, where the 2- to 10-membered alkylene group is saturated or has one or more, e.g. 1, 2, 3 or 4, non-conjugated ethylenic double bonds, and where the 2- to 10-membered alkylene group is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10-Aryl and C3-C9-Hetaryl; where R 15 and R 17 for hydrogen, C1-C6 alkyl, C1-C6 alkenyl, C6-C 10 -aryl, C3-C9-hetaryl, C7-C 12 - Aralkyl or C7-C 12 -alkylaryl; R 16a and R 16b each independently hydrogen, C1- to C6-alkyl, C6- to C 10 -aryl, C7- to C 12 -aralkyl or C7- to C 12 -alkylaryl; or R 16a and R 16b together may also represent an alkylene chain having 2 to 5 carbon atoms, which may be interrupted by N or O; and R 16c for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12-Alkylaryl. Examples of compounds of the general formulas (VI) or (VII) are cyclohexene, 1-butene, 1-octene, 3,3-dimethylbutene, 2,3,3-dimethylbutene, CH2=CH(Ph)CH(CH3)2, (Ph)CH=CH(Ph), (Ph)CH=C(Ph), dimethyl itaconic acid, isophorone, pseudoionone, α-ionone, β-ionone, (+)-limonene, and β-pinene. The prochiral α,β-unsaturated carbonyl compound is preferably a prochiral, α,β-unsaturated ketone or, in particular, a prochiral, α,β-unsaturated aldehyde. Accordingly, the process according to the invention is preferably suitable for the preparation of optically active aldehydes or ketones by asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes or ketones. The process according to the invention is particularly preferably suitable for the preparation of optically active aldehydes by asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes.In a preferred embodiment of the process according to the invention, the prochiral α,β-unsaturated carbonyl compound is selected from compounds of the general formula. , where R 12 and R 13 are different from each other and each represents an unbranched, branched or cyclic hydrocarbon radical having 1 to 25 carbon atoms, which is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and which is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10 -aryl and C3-C9-hetaryl; R 14represents hydrogen or an unbranched, branched or cyclic hydrocarbon radical having 1 to 25 carbon atoms, which is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and which is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10 -Aryl and C3-C9-Hetaryl; or R 14 together with one of the residues R 12 or R 13 may also be a 3 to 25-membered alkylene group, in which 1, 2, 3 or 4 non-adjacent CH2 groups are replaced by O or NR 16cmay be replaced, wherein the alkylene group is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and wherein the alkylene group is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C1-C4 alkyl, C6-C 10 -aryl and C3-C9-hetaryl, where two substituents can also together represent a 2 to 10-membered alkylene group, where the 2- to 10-membered alkylene group is saturated or has one or more, e.g. 1, 2, 3 or 4, non-conjugated ethylenic double bonds, and where the 2- to 10-membered alkylene group is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6-C 10-Aryl and C3-C9-Hetaryl; where R 17 for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl; R 16a , R 16b each independently hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 - Aralkyl or C7-C 12 -alkylaryl or R 16a and R 16b together may also represent an alkylene chain having 2 to 5 carbon atoms, which may be interrupted by N or O; and R 16c for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl. In the definitions of the radicals R 12 , R 13 and R 14 The unbranched, branched or cyclic hydrocarbon residues with 1 to 25 carbon atoms mentioned above are usually unbranched C1-C 25 -alkyl groups, unbranched C2-C 25 - Alkenyl groups, unbranched C4-C 25-alkadienyl groups, branched C3-C 25 -alkyl groups, branched C3-C 25 -alkenyl groups, branched C5-C 25 -alkadienyl groups and C3-C 25 - cycloalkyl groups or C3-C 24-Cycloalkyl groups which are substituted by one or more, e.g., 1, 2, 3, or 4, C1-C4-alkyl groups, as defined above. Cyclic hydrocarbon radicals also include those cyclic hydrocarbon radicals which have a phenyl ring which optionally carries one or more, e.g., 1, 2, 3, 4, 5, or 6, C1-C4-alkyl groups, where the phenyl ring is bonded directly to the ethylenically unsaturated double bond or the carbonyl group in formula (II) or is bonded via a C1-C6-alkylene group. An alkenyl group is understood to mean a linear or branched aliphatic hydrocarbon radical which is monounsaturated. An alkdienyl group is understood to mean a linear or branched aliphatic hydrocarbon radical which is diunsaturated. In the radicals R defined 14 The 3- to 25-membered alkylene groups mentioned, which are saturated, are generally unbranched or branched C3-C25 -alkylene groups, as defined above. In the case of the radicals R 14 The 3- to 25-membered alkylene groups mentioned, which have one or more, e.g. 1, 2, 3 or 4, non-conjugated ethylenic double bonds, are generally unbranched or branched C3-C 25 -alkenylene groups, as defined above. Preferably, one of the radicals R 12 and R 13 represents methyl or ethyl, in particular methyl, and the other radical represents an unbranched, branched or cyclic hydrocarbon radical having 3 to 25 carbon atoms, which is saturated or has one or more, e.g. 1, 2, 3, 4 or 5, preferably non-conjugated ethylenic double bonds, and which is unsubstituted or carries one or more, e.g. 1, 2, 3 or 4, identical or different substituents selected from OR 17 , NR 16a R 16b , halogen, C6 to C 10-aryl and C3- to C9-hetaryl. In particular, one of the radicals R 12 and R 13 represents methyl or ethyl, in particular methyl, and the other radical represents a straight-chain, branched, or cyclic hydrocarbon radical having 3 to 25 carbon atoms, which is saturated or has one or more, e.g., 1, 2, or 3, preferably non-conjugated, ethylenic double bonds. R 14 represents in particular hydrogen. In a very preferred embodiment of the process according to the invention, the prochiral α,β-unsaturated carbonyl compound is selected from compounds of the general formula , where R 12 and R 13each represent an unbranched or branched hydrocarbon radical having 2 to 25, in particular 3 to 20, carbon atoms, which is saturated or has 1, 2, 3, 4 or 5 non-conjugated ethylenic double bonds, such as, for example, neral / geranial. Accordingly, the process according to the invention can be used to prepare the corresponding α,β-saturated aldehydes or ketones of the formula (VIII), such as, for example, citronellal, in optically active form by asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes or ketones of the general formulas (VIII), (VIIIa) and (VIIIb), wherein the carbon atom which forms the radicals R 12 and R 13 represents the center of asymmetry created by hydrogenation. In the formula, R 12 , R 13 U.N 14 d R has the meanings given for formula (VIII), in particular the meanings given for formulas (VIIIa) and (VIIIb). The corresponding α,β-saturated aldehydes are accessible through the inventive asymmetric, i.e., enantioselective hydrogenation of the α,β-unsaturated aldehydes of formulas (VIIIa) or (VIIIb). The compounds of formulas (VIIIa) and (VIIIb) represent E / Z double bond isomers of each other. In principle, the corresponding optically active aldehydes are accessible starting from both double bond isomers of formulas (VIIIa) and (VIIIb). Depending on the choice of the enantiomeric form of the catalyst, i.e., depending on the choice of the (+)- or (-)-enantiomer of the catalyst or the (+)- or (-)-enantiomer of the chiral ligand used, one of the enantiomers of the optically active aldehyde is preferably obtained from the E- or Z-double bond isomer used in the inventive manner. The same applies to the aforementioned substrates or

[0041] Product classes. In principle, mixtures of the two double bond isomers can also be reacted according to the invention. This yields mixtures of the two enantiomers of the desired target compound.

[0042] The preparation process according to the invention is carried out in the presence of an optically active iron carbonyl complex of the general formula (I) which is soluble in the reaction mixture or of an iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO (I') or LFeCO (I").

[0043] The present invention also relates to a process for the preparation of an iron carbonyl complex of the general formula (I) comprising the reaction of a chiral, bidentate bisphosphine ligand L, which is preferably selected from compounds

[0044] enantiomers, with an iron precursor compound, where R 1 , R 2 , R 3 , R 4 , R 5 , R6 , R 7 and R 8 have the meaning given above.

[0045] The iron precursor compound is preferably a compound of the formula Fe(COT)(CO)3(Va) or Fe(CO)5(Vb), where COT is cyclooctatetraene. Fe(COT)(CO)3(Va) is preferably reacted with the chiral, bidentate bisphosphine ligand L at a temperature of 20 to 120 °C. Fe(CO)5(Vb) can also be reacted directly with the bidentate bisphosphine ligand L. Alternatively, an Fe(II) source can be used under reductive conditions. For example, FeBr2 or FeCl2 can be treated with the bidentate bisphosphine ligand L and subsequently reacted with CO, H2 / CO, or CO and a reducing agent.

[0046] The iron carbonyl complex can be generated in-situ by reacting an achiral iron precursor compound with a chiral, bidentate bisphosphine ligand L and optionally CO before or during hydrogenation.

[0047] In this context, the term "in situ" means that the iron carbonyl complex is generated directly before or at the beginning of the hydrogenation. Preferably, the catalyst is generated before the hydrogenation.

[0048] The iron carbonyl complex (= catalyst) can be pretreated with a gas mixture containing carbon monoxide and hydrogen before hydrogenation and / or the hydrogenation can be carried out in the presence of carbon monoxide additionally added to the reaction mixture. This means that the iron carbonyl complex used is either pretreated with a gas mixture containing carbon monoxide and hydrogen before hydrogenation (i.e., a so-called preformation is carried out), or the hydrogenation is carried out in the presence of carbon monoxide additionally added to the reaction mixture, or a preformation is carried out and then the hydrogenation is carried out in the presence of carbon monoxide additionally added to the reaction mixture. In this preferred embodiment, the iron carbonyl complex is preferably pretreated with a gas mixture containing carbon monoxide and hydrogen, and the hydrogenation is carried out in the presence of carbon monoxide additionally added to the reaction mixture.In this preferred embodiment, the aforementioned pretreatment of the iron carbonyl complex is carried out with a gas mixture comprising 20 to 90 vol.% carbon monoxide, 10 to 80 vol.% hydrogen and 0 to 5 vol.% of other gases, the aforementioned volume fractions adding up to 100 vol.%, at a pressure of 5 to 100 bar. In addition, excess carbon monoxide is separated from the catalyst thus obtained before use in the hydrogenation. The term excess carbon monoxide is understood to mean carbon monoxide that is present in the resulting reaction mixture in gaseous or dissolved form and is not bound to the iron carbonyl complex. Accordingly, the excess carbon monoxide not bound to the iron carbonyl complex is at least largely removed, i.e. to an extent that any residual amounts of dissolved carbon monoxide do not have a disruptive effect on the subsequent hydrogenation.This is usually ensured if about 90%, preferably about 95% or more, of the carbon monoxide used for preformation is removed. The excess carbon monoxide is preferably removed completely from the iron carbonyl complex obtained by preformation. The excess carbon monoxide can be separated from the reaction mixture containing the iron carbonyl complex in various ways. Preferably, the iron carbonyl complex or the iron carbonyl complex is depressurized.the mixture containing the iron carbonyl complex obtained by preformation to a pressure of up to about 5 bar (absolute), preferably, especially when carrying out the preformation in the pressure range from 5 to 10 bar, to a pressure of less than 5 bar (absolute), preferably to a pressure in the range from about 1 bar to about 5 bar, preferably 1 to less than 5 bar, particularly preferably to a pressure in the range from 1 to 3 bar, very particularly preferably to a pressure in the range from about 1 to about 2 bar, especially preferably to atmospheric pressure, so that gaseous, unbound carbon monoxide escapes from the preformation product. The above-mentioned depressurization of the preformed catalyst can be carried out, for example, using a high-pressure separator, as is known per se to the person skilled in the art.Such separators, in which the liquid is in the continuous phase, are described, for example, in: Perry's Chemical Engineers' Handbook, 1997, 7th ed., McGraw-Hill, pp. 14.95 and 14.96; the prevention of possible droplet entrainment is described on pages 14.87 to 14.90. The expansion of the preformed iron carbonyl complex can be carried out in one or two stages until the desired pressure in the range from 1 bar to about 5 bar is reached, the temperature usually falling to 10 to 40°C. Alternatively, the removal of excess carbon monoxide can be achieved by so-called stripping of the iron carbonyl complex or the mixture containing the iron carbonyl complex with a gas, advantageously with a gas that is inert under the reaction conditions. The term stripping is understood by those skilled in the art to mean the introduction of a gas into the iron carbonyl complex or the mixture containing the iron carbonyl complex.The reaction mixture containing the iron carbonyl complex is described, for example, in WRA Vauck, HA Müller, "Grundoperationenchemischer Verfahrenstechnik" (Unitary Operations of Chemical Process Engineering), Deutscher Verlag für Grundstoffchemie Leipzig, Stuttgart, 10th edition, 1984, page 800. Examples of suitable inert gases include: hydrogen, helium, neon, argon, xenon, nitrogen, and / or CO2, preferably hydrogen, nitrogen, or argon. The subsequent hydrogenation is preferably carried out with hydrogen having a carbon monoxide content in the range of 50 to 3000 ppm, in particular in the range of 100 to 2000 ppm, especially in the range of 200 to 1000 ppm, and most especially in the range of 400 to 800 ppm.The hydrogenation is advantageously carried out at a pressure of about 5 to about 200 bar, in particular from about 10 to about 100 bar, especially at about 60 to about 100 bar, and a temperature of generally about 0°C to about 120°C, preferably about 20°C to about 110°C, in particular at about 50°C to about 100°C. The choice of solvent to be used to carry out the hydrogenation is not critical. Suitable solvents that are inert under the reaction conditions include, for example, ethers, alcohols (such as ethanol, methanol, iPrOH, nPrOH, n-BuOH, and cyclohexanol), tetrahydrofuran, methyltetrahydrofuran, toluene, xylenes, chlorobenzene, octadecanol, biphenyl ether, Texanol, Marlotherm, Oxo-oil 9N (hydroformylation products from isomeric octenes, BASF SE), and the like. The substrate to be reacted, the product, or any high-boiling by-products that may arise during the reaction can also serve as the solvent medium.Suitable reaction vessels for carrying out the hydrogenation according to the invention are in principle all those which allow reactions under the stated conditions, in particular pressure and temperature, and are suitable for hydrogenation reactions, such as, for example, autoclaves, tubular reactors, bubble columns, etc. If the hydrogenation is carried out using high-boiling, generally viscous solvents, as described above (for example the solvents octadecanol, biphenyl ether, Texanol, Marlotherm. ®, oxo oil 9N) or if the hydrogenation is carried out without the additional use of solvent but with the accumulation of high boilers which are formed to a small extent as by-products (such as, for example, dimers or trimers which are formed by reactions of the reactants or products and subsequent reactions), it can be advantageous to ensure good gas introduction and good mixing of the gas phase and condensed phase. This can be achieved, for example, by carrying out the hydrogenation step of the process according to the invention in a gas circulation reactor. Gas circulation reactors are known per se to the person skilled in the art and are described, for example, in P. Trambouze, J.-P. Euzen, Chemical Reactors, Ed. Technip, 2004, pp. 280-283 and P. Zehner, R. Benfer, Chem. Eng. Sci. 1996, 51, 1735-1744 and, for example, in EP 1140349. When using a gas circulation reactor as mentioned above, it has proven particularly advantageous to use the gas orA gas mixture (hydrogen containing carbon monoxide) is introduced into the gas circulation reactor by means of a simple nozzle or a two-fluid nozzle in parallel with the reactants introduced into the reactor and / or the circulating reaction mixture or the catalyst. The two-fluid nozzle is characterized in that the liquid and gas introduced into the reactor pass under pressure through two separate, nested tubes to the nozzle mouth and are combined there. The process according to the invention can be carried out successfully with or without the addition of tertiary amines. Instead of tertiary amines, alkoxides, carbonates or hydrogen carbonates can also be added. The process according to the invention is preferably carried out in the absence, i.e. without the addition of additional tertiary amines or in the presence of only catalytic amounts of additional tertiary amines.The amount of amine used can be between 0.5 and 500 mol equivalents based on the amount of metal used, but preferably 1 to 100 mol equivalents based on the amount of metal used. The choice of tertiary amine is not critical. In addition to short-chain alkylamines, such as triethylamine, long-chain alkylamines, such as tridodecylamine, can also be used. In a preferred embodiment, the hydrogenation process according to the invention is carried out in the presence of a tertiary amine, preferably tridodecylamine, in an amount of about 2 to 30 mol equivalents, preferably about 5 to 20 mol equivalents and particularly preferably 5 to 15 mol equivalents based on the amount of transition metal used. The reaction is advantageously stopped when the target compound has been obtained in the desired yield and, where appropriate, the desired optical activity, iewith the desired enantiomeric excess (ee) is present in the reaction mixture, as can be determined by a person skilled in the art through routine investigations, for example by means of chromatographic methods. The hydrogenation is usually complete after about 1 to about 150 hours, often after about 2 to about 24 hours. The process according to the invention makes it possible to provide hydrogenated olefins, optically active carbonyl compounds, in particular optically active aldehydes, in high yields and enantiomeric excesses. The desired asymmetrically hydrogenated compounds are usually obtained in an enantiomeric excess of at least 80% ee, often with an enantiomeric excess of about 85 to about 99% ee. It should be noted that the maximum achievable enantiomeric excess can depend on the purity of the substrate used, in particular with regard to the isomeric purity of the double bond to be hydrogenated.Accordingly, particularly suitable starting substances are those which have an isomer ratio of at least about 90:10, preferably at least about 95:5 with regard to the E / Z double bond isomers. The homogeneous catalysts used can be stabilized by the preformation and / or by the carbon monoxide additionally introduced into the reaction system, which on the one hand significantly increases the service life of the catalysts and on the other hand enables the homogeneous catalysts to be reused. For example, the reaction product obtained can be removed from the reaction mixture by processes known to those skilled in the art, such as distillation, and the remaining catalyst can be used in further reactions, if appropriate after further preformation. The process according to the invention can accordingly be carried out either discontinuously (batchwise) orcan be operated both semi-continuously and continuously and is particularly suitable for reactions on an industrial scale. In a preferred embodiment of the process according to the invention, the organic, unsaturated compound is converted into the desired organic compound in the presence of an iron precursor compound which is soluble in the reaction mixture, for example Fe(COT)(CO)3(Va) or Fe(COT)(CO)3(Va). The catalyst is preferably preformed under the above-mentioned conditions and the asymmetric hydrogenation is then carried out in the presence of hydrogen which contains in particular 50 to 3000 ppm of carbon monoxide. In the preferred embodiment, the addition of solvents is advantageously dispensed with and the said reactions are carried out in the substrate to be reacted or the product and, if appropriate, in high-boiling by-products as the solvent medium. Particular preference is given to continuous reaction with reuse orRecycling of the homogeneous catalyst stabilized according to the invention. The following examples serve to illustrate the invention without limiting it in any way: Examples Example 1: Preparation of Fe(CO)3(R,R-Chiraphos) Under a protective gas atmosphere, Fe(COT)(CO)3 (885 mg, 3.63 mmol) is dissolved in absolute toluene (20 mL) at room temperature, and R,R-Chiraphos (1.65 g, 3.87 mmol) is added. The dark red solution is stirred at 105°C for 96 h. The solution is filtered through silica gel and washed with toluene (20 mL). The filtrate is concentrated in vacuo and then redissolved in toluene (10 mL). It is cooled to -20°C, which leads to the precipitation of a yellow solid. This is separated from the solution by decantation. Washing with pentane (10 mL) and drying in vacuo afforded Fe(CO)3(R,R-Chiraphos) as a yellow solid (1.02 g, 1.8 mmol, 50% yield). 1H NMR (500 MHz, CD2Cl2) δ = 7.7-7.5 (m, 10 H), 7.3-7.4 (m, 10 H), 2.16 (s, CH, 2 H), 0.99 (s, CH3, 6 H); 13 C NMR (125 MHz, C6D6) δ = 221 (CO), 136.7, 134.6, 133.8, 132.0, 130.4, 130.2, 129.1, 128.1 (Ar-C) 40.5 (CH), 35.7 (CH) ppm; 31 P NMR (203 MHz, CD2Cl2) δ = 96 ppm; MS (LIFDI) C 31 H 28 FeO3P2([M] + ): Calculated: 566; Found: 566; IR (KBr): δ (CO) = 1977, 1906, 1883 cm -1 ; Drehwert (Jasco P-2000 polarimeter): [ α]D 25= -278 (c = 0.54 in toluene). The iron carbonyl complex A-1, (Fe(CO)3(R,R-Chiraphos), crystallizes in an orthorhombic unit cell, space group P212121 (see Fig. 1 and 2). The structure of Fe(CO)3(R,R-Chiraphos) was determined by single crystal X-ray diffraction: details can be found in Tables 1, 2 and 3. Table 1: Crystal structure data of Error! Reference source not found.. Formula C31H28FeO3P2 Molar mass 566.32 g / mol Temperature 120(2) K Wavelength 1.54178 Å Crystal 0.055 x 0.083 x 0.180 mm Habit clear, yellow crystal Crystal system orthorhombic Space group P212121 Unit cell a = 8.9637(3) Å α = 90° b = 16.3629(5) Å β = 90° c = 18.8569(6) Å γ = 90° volume 2765.78(15) Å 3 Z 4 Density (calculated) 1,360 g / cm 3 Absorption coefficient 5.709 mm -1F(000) 1176 Table 2: Measurement parameters and structure solution of Error! Reference source not found.. Theta 3.58 to 74.60° Reflections measured 28185 of which independent 5520 [R(int) = 0.0626] Structure solution Direct method Structure solution program XT, VERSION 2018 / 2 Refinement method Full-matrix least-squares on F 2 Refinement program SHELXL-2019 / 1 (Sheldrick, 2019) Goodness-of-fit regarding F2 0.978 Δ / σmax 0.001 R Indices 4989 data; R1 = 0.0330, wR2 = 0.0745 I>2σ(I) all data R1 = 0.0377, wR2 = 0.0765 Flack parameter 0.049(3) max. residual electron density between 0.439 and -0.265 eÅ -3 Instrument / Radiation Bruker D8 diffractometer with a PHOTON-II CCD detector with φ and ω-scans with Cu-Kα radiation (λ = 1.54178 Å) Table 3: Coordinates and isotropic atomic deflection parameters (Å 2) x / a y / b z / c U(eq) Fe1 0.32820(5) 0.55049(3) 0.69962(2) 0.02755(12) P1 0.54979(9) 0.51461(5) 0.74271(4) 0.02947(16) P2 0.43184(9) 0.51782(4) 0.59609(4) 0.02915(16) O1 0.0389(3) 0.57334(16) 0.63139(12) 0.0424(5) O2 0.3265(3) 0.71543(14) 0.76005(14) 0.0476(6) x / a y / b z / c U(eq) O3 0.1730(3) 0.43712(15) 0.79410(14) 0.0470(5) C1 0.5460(4) 0.46560(18) 0.82956(15) 0.0318(6) C20.5221(4) 0.3813(2) 0.83528(17) 0.0349(7) C3 0.5044(4) 0.3464(2) 0.90197(18) 0.0396(7) C4 0.5085(4) 0.3936(2) 0.96207(17) 0.0390(7) C50.5291(4) 0.4776(2) 0.95678(17) 0.0379(7) C6 0.5486(4) 0.5134(2) 0.89064(16) 0.0363(6) C70.4626(4) 0.59812(18) 0.52964(15) 0.0307(6) C8 0.5886(4) 0.6016(2) 0.48679(18) 0.0398(7) C9 0.6006(4) 0.6608(2) 0.43373(18) 0.0414(7) C10 0.4874(4) 0.7156(2) 0.42284(16) 0.0368(7) C11 0.3622(4) 0.7135(2) 0.46520(17) 0.0403(7) C12 0.3502(4) 0.6553(2) 0.51898(16) 0.0354(7) C13 0.6935(4) 0.59338(19) 0.75272(16) 0.0334(6) C14 0.6797(4) 0.66626(19) 0.71472(16) 0.0352(6) C15 0.7842(4) 0.7285(2) 0.72273(18) 0.0388(7) C16 0.9040(5) 0.7177(2) 0.7674(2) 0.0453(8) C17 0.9214(4) 0.6449(2) 0.8042(2) 0.0466(8) C18 0.8169(4) 0.5829(2) 0.79708(18) 0.0401(7) C19 0.6337(4) 0.43778(19) 0.68269(16) 0.0340(6) C20 0.6227(4) 0.47189(19) 0.60680(16) 0.0341(6) C21 0.6637(5) 0.4082(2) 0.55123(18) 0.0435(7) C22 0.1543(4) 0.56570(19) 0.65681(15) 0.0336(6) C23 0.3332(4) 0.65092(19) 0.73449(16) 0.0351(6) C24 0.2401(4) 0.47893(19) 0.75624(17) 0.0343(6) C25 0.3295(4) 0.44128(19) 0.54327(16) 0.0368(6)C26 0.2551(6) 0.3784(2) 0.5785(2) 0.0516(10) C27 0.1812(8) 0.3182(3) 0.5401(3) 0.0696(14) C28 0.1781(7) 0.3212(2) 0.4672(2) 0.0599(11) C29 0.2508(5) 0.3829(2) 0.4319(2) 0.0448(8) C30 0.3267(4) 0.4429(2) 0.46944(16) 0.0376(6) C31 0.7919(4) 0.4110(2) 0.7022(2) 0.0412(7) Example 2: Hydrogenation with Fe(CO)3(R,R-Chiraphos) as catalyst Fe(CO)3(R,R-Chiraphos) (70 mg, 0.12 mmol) and cyclohexene (5.0 g, 61 mmol) are placed in toluene (10 ml, Sigma-Aldrich) in a 60 ml steel autoclave (V2A steel, manufacturer Premex, magnetically coupled gassing stirrer, 1000 rpm) and adjusted to 60 bar hydrogen pressure. The temperature is increased to the values ​​specified in the table below. Once the desired reaction temperature is reached, a hydrogen pressure of 80 bar is set. After 20 h, the reaction mixture is cooled to room temperature and decompressed. The reaction mixture is analyzed by GC using a VF-Wax column (30 mx 0.25 mm / 0.5 μm; 5 min at 60°C, then at 20°C / min to 250°C; flow rate: 2.0 mL / min; H2 as carrier gas). Conversion is determined using GC area %. a) Conversion after 20 hours (GC), b) Procedure as in Example 2, except that 5 g of another reactant are used instead of 5 g of cyclohexene, c) Addition of 1 mol% KOtBu, d) Product: N-(1-phenylethyl)aniline.

Claims

Patent claims 1. Iron carbonyl complex of the general formula LFe(CO)3(I), where L represents a chiral, bidentate bisphosphine ligand, which is preferably selected from compounds of the formula and their enantiomers, where R 1 and R 2 each independently of one another represents an unbranched, branched or cyclic hydrocarbon radical having 1 to 20 carbon atoms, which is saturated or may have one or more, generally 1 to about 4, non-conjugated, ethylenic double bonds and which is unsubstituted or carries one or more, generally 1 to 4, identical or different substituents selected from OR 9 , NR 10 R 11 , halogen, C6-C 10 -aryl and C3-C9-hetaryl, or R 1 and R 2together may also represent a 2 to 10-membered alkylene group or a 3 to 10-membered cycloalkylene group, in which 1, 2, 3 or 4 non-adjacent CH2 groups are replaced by O or NR 9c may be replaced, wherein the alkylene group and the cycloalkylene group are saturated or have one or two non-conjugated ethylenic double bonds, and wherein the alkylene group and the cycloalkylene group are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl; R 3 and R 4 each independently represents hydrogen or straight-chain or branched C1-C4 alkyl and R 5 , R 6 , R 7 and R 8 are the same or different and for C6-C 10 -aryl which is unsubstituted or carries one or more substituents selected from C1-C6 alkyl, C3-C6 cycloalkyl, C6-C 10-Aryl, C1-C6 alkoxy and amino; R 9c for hydrogen, C1-C6 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, R 9 , R 10 and R 11 each independently hydrogen, C1-C4 alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, where R 10 and R 11 together may also represent an alkylene chain with 2 to 5 carbon atoms, which may be interrupted by N or O.

2. Iron carbonyl complex according to claim 1, wherein R 1 and R 2 each independently represents an unbranched, branched or C1-C4-alkyl radical or R 1 and R 2together or represent a C3-C7 alkanediyl radical, C3-C7 alkenediyl radical, C5-C7 cycloalkanediyl radical or a C5-C7 cycloalkenediyl radical, where the four aforementioned radicals are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl; R 3 and R 4 each independently of one another denotes hydrogen or straight-chain or branched C1-C4-alkyl; and wherein in the C3-C7-alkanediyl radical, 1 or 2 non-adjacent CH2 groups may additionally be replaced by O or one CH2 group may be replaced by N-CH2Ph; and R 5 , R 6 , R 7 and R 8 stand for phenyl.

3. Iron carbonyl complex according to claim 1, wherein the chiral, bidentate Bisphosphine ligand L is a compound of formulas (1) to (91):

4. Iron carbonyl complex according to claim 1 or 2, wherein the chiral, bidentate bisphosphine ligand L is a compound of general formula (II).

5. Iron carbonyl complex according to claim 4, wherein the chiral, bidentate Bisphosphine ligand from compounds of the general formula where Ph is phenyl and Bn is benzyl.

6. Iron carbonyl complex according to claim 5, wherein the chiral, bidentate Bisphosphine ligand either the compound of formula (IIa) or Formula (IIb), where Ph is phenyl.

7. An iron carbonyl complex according to claim 6, namely Fe(CO)3(R,R-Chiraphos), which crystallizes in an orthorhombic unit cell, space group P212121.

8. A process for preparing an organic compound by hydrogenating an unsaturated organic compound with hydrogen in the presence of at least one iron carbonyl complex according to any one of claims 1 to 7 or an iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO(I') or LFeCO2(I'').

9. Use of an iron carbonyl complex according to any one of claims 1 to 7 or an iron carbonyl complex formed therefrom, containing a fragment of the formula LFeCO(I') or LFeCO2(I''), for preparing an organic compound by hydrogenating an unsaturated organic compound with molecular hydrogen.The process according to claim 8, or the use according to claim 9, wherein the unsaturated organic compound is a disubstituted or trisubstituted, prochiral or non-prochiral, unsaturated organic compound, in particular a prochiral or non-prochiral, unsaturated carbonyl compound.

11. The process or use according to claim 8, wherein the unsaturated compound is a prochiral or non-prochiral, α,β-unsaturated ketone or a prochiral or non-prochiral α,β-unsaturated aldehyde. 12.Process according to one of claims 8, 10 and 11, which has at least one or all of the following features a - h: a) carrying out the hydrogenation at a hydrogen pressure of 5 to 200 bar, in particular at a hydrogen pressure of 10 to 100 bar; b) carrying out the process batchwise or continuously; c) in-situ generation of the iron carbonyl complex before or during the hydrogenation by reacting an achiral iron precursor compound with a chiral, bidentate bisphosphine ligand L and optionally CO; d) pretreating the catalyst before the hydrogenation with a gas mixture containing carbon monoxide or carbon monoxide / hydrogen;. e) carrying out the hydrogenation in the presence of carbon monoxide additionally added to the reaction mixture; f) carrying out the hydrogenation with hydrogen having a carbon monoxide content in the range from 50 to 3000 ppm, in particular in the range from 100 to 2000 ppm; g) carrying out the hydrogenation in a gas circulation reactor; h) carrying out the hydrogenation in a gas circulation reactor, wherein the unsaturated compound and the hydrogen are introduced into the gas circulation reactor by means of a two-component nozzle.

13. A process for the preparation of an iron carbonyl complex according to one of the Claims 1 to 7, comprising the reaction of a chiral, bidentate Bisphosphine ligand L, which is preferably selected from compounds of formula and their enantiomers, with an achiral iron precursor bond and optionally CO, where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R7 and R 8 have the meaning given in claim 1.

14. The process according to claim 13, wherein the iron precursor compound is a compound of the formula Fe(COT)(CO)3(Va) or Fe(CO)5(Vb), where COT is cyclooctatetraene.

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