Title of Invention	RUTHENIUM COMPLEXES HAVING (P-P)-COORDINATED DIPHOSPHORUS DONOR LIGANDS AND PROCESSES FOR PREPARING THEM
Abstract	The invention relates to ruthenium complexes which have a chiral diphosphorus donor ligand and in which the ruthenium has the oxidation state (+11) and the chiral diphosphorus donor ligand has bidentate P-P coordination to the ruthenium. The ruthenium complexes are present in two forms (cationic type A and uncharged type B), are cyclic and have a four- to six-membered ring incorporating the diphosphorus donor ligand. The chiral diphosphorus donor ligands are selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphosphonites and diazaphospholanes. Furthermore, processes for preparing the ruthenium complexes of types A and B, which are based on ligand exchange reactions, are described. The Ru complexes are used as catalysts for homogeneous asymmetric catalysis for preparing organic compounds.

Title of Invention

RUTHENIUM COMPLEXES HAVING (P-P)-COORDINATED DIPHOSPHORUS DONOR LIGANDS AND PROCESSES FOR PREPARING THEM

Abstract

The invention relates to ruthenium complexes which have a chiral diphosphorus donor ligand and in which the ruthenium has the oxidation state (+11) and the chiral diphosphorus donor ligand has bidentate P-P coordination to the ruthenium. The ruthenium complexes are present in two forms (cationic type A and uncharged type B), are cyclic and have a four- to six-membered ring incorporating the diphosphorus donor ligand. The chiral diphosphorus donor ligands are selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphosphonites and diazaphospholanes. Furthermore, processes for preparing the ruthenium complexes of types A and B, which are based on ligand exchange reactions, are described. The Ru complexes are used as catalysts for homogeneous asymmetric catalysis for preparing organic compounds.

Full Text	Ruthenium complexes having (P-P)-coordinated disphosphorus donor ligands and processes for preparing them Description The present invention relates to ruthenium complexes for homogeneous catalysis, in particular P-P- coordinated cyclic ruthenium complexes having chiral diphosphorus donor ligands. The invention further provides processes for preparing them and also the use of these complexes as catalysts for homogeneous catalysis, in particular for enantioselective hydrogenation. Chiral diphosphorus donor ligands have been found to be valuable ligands for catalytically active metal complexes which are used in homogeneous catalysis for the enantioselective hydrogenation of organic compounds. Fields of use are the preparation of intermediates or active compounds, for example pharmaceuticals, pesticides, flavors or fragrances. In enantioselective hydrogenation, these diphosphorus donor ligands are used together with suitable noble metal complexes. Organometallic Ru compounds used in these hydrogenations are, for example, [Ru(COD)Y2]x, [Ru(NBD)Y2]x, [Ru(aromatic)Y2]x or [Ru(COD)2-methyl- allyl)2] (where X = 2; Y = halide, COD = 1,5-cyclo- octadiene, NBD = norbornadiene, aromatic = for example p-cumene or another benzene derivative). EP 1622920B1 discloses transition metal complexes having ferrocenyldiphosphine ligands. Complexes having specific P-P coordination of the phosphine ligands are Ru complexes having (P-P)-coordinated diphosphorus donor ligands are known from the literature. M. Sato and M. Asai (J. of Organometallic Chemistry 508 (1996) pp. 121-127) describe permethylcyclopentadienyl- Ru'(ll) complexes having dppf, BINAP and DIOP ligands. As a result of the permethylcyclopentadienyl radical, these complexes are very stable; use for catalytic hydrogenation is not described. C. Standfest-Hauser, C. Slugovc et al. (J. Chem. Soc. Dalton Trans., 2001, pp. 2989-2995) report cyclic Ru(II) semisandwich complexes which likewise have a cyclopentadienyl ligand and also chelating phosphino- amine ligands. These complexes contain a cyclopenta- dienyl ligand ("Cp ligand") and are not very suitable for use as catalysts for homogeneous asymmetric hydrogenation. They are normally used in a specific catalysis reaction (namely transfer hydrogenation), with the Cp ligand stabilizing the catalyst and having to be coordinated to the metal during catalysis. J.B. Hoke et al. (J. of Organomet. Chem., 1993, 455, pp. 193-196) describe ruthenium complexes in which BINAP ligands form a seven-member ed ring with the Ru. The complexes contain one cyclopentadienyl group. They are very stable but display little activity in catalytic hydrogenation and some of them are unselective since the Cp ligand is bound very strongly to the metal. P.S. Pregosin et al. (Organometallics, 1997, 16, pp. 537-543) have reported a ruthenium complex which bears the MeO-BIPHEP ligand and additionally has a cycloocta- dienyl radical. The complex can be prepared only by means of a complicated process and is very air- and moisture-sensitive. Use for catalytic hydrogenation is not described. A similar complex bearing the BINAP ligand has been described by S.H. Bergens et al. (Organometallics, 2004, 23, pp. 4564-4568). An aceto- nitrile complex was isolated in the synthesis and this is not very active in catalysis. A. Salzer et al. (Organometallics, 2000, 19, pp. 5471- 5476) have reported the preparation of a seven-membered BINAP-ruthenium complex from a (bispentadienyl)Ru compound as starting complex. D.A. Dobbs et al. (Angew. Chem. 2000, volume 112, pp. 2080-2083) describe a ruthenium-containing precatalyst having a P-P-coordinated DuPhos ligand. The cyclic compound is an Ru hybrid species and has an uncharged cyclooctatrienyl ligand. It is very sensitive and was prepared in a glove box (inert gas: Ar containing very suitable for industrial use. WO 00/37478 describes transition metal complexes which have a metal atom of transition group 7 or 8 and in which both P atoms of a diphosphine ligand are simultaneously coordinated to the central atom, but the complexes are neither isolated nor characterized. No preparative method is described; rather, the complexes are generated by combining the ligands and the appropriate transition metal salts in the reaction solvent shortly before use ("in-situ"). These in-situ processes are prior art. Few studies have hitherto been carried out on the structure of the metal complexes generated in-situ; the corresponding complexes were not isolated but instead used directly in the reaction mixture for homogeneous catalysis, in particular for catalytic hydrogenation. The mechanistic studies are carried out using model systems which do not correspond to the real active catalytic species. US 6,455,460 describes a ruthenium catalyst obtainable by a process which comprises putting together an appropriate Ru(II) complex, a chelating diphosphine and an acid comprising an non-coordinating anion. The reaction is performed under an oxygen-free atmosphere. Disadvantages of the catalytic hydrogenation processes described hitherto and the catalysts used therein are, in particular, the low reactivity, the low enantioselectivities and a high consumption of noble metal-containing catalyst, i.e. a low "substrate/catalyst" (S/C) ratio. Furthermore, long hydrogenation times are required. In addition, many of the complexes described are difficult to synthesize, are air-sensitive and are not very suitable for industrial use. It was therefore an object of the present invention to provide improved catalysts for homogeneous, asymmetric hydrogenation which overcome the abovementioned disadvantages. A further object was to provide suitable processes for preparing the catalysts of the invention. In particular, these processes should be able to be used in industry and be environmentally friendly and inexpensive. This object is achieved by the provision of the ruthenium complexes of the types A and B as claimed in claim 1 of the invention. Furthermore, processes for preparing the inventive complexes of types A and B are provided in claims 12 and 22. Preferred embodiments of the complexes and the processes are described in the respective dependent claims. The present invention describes ruthenium complexes having a chirai diphosphorus donor iigand of the P(1)-P(2) type for homogeneous catalysis. The complexes are of two different types (type A and type B) , with the ruthenium having the oxidation state +II and the diphosphorus donor ligands displaying bidentate P-P coordination to the Ru. The ruthenium complexes of the invention are cyclic and together with the diphosphorus donor ligand have a four- to six-membered ring. In the search for well-defined Ru complexes having these chiral diphosphorus donor ligands, it has surprisingly been found that simultaneous coordination of both P atoms of the diphosphorus donor ligands to a central Ru atom can be achieved under particular conditions. This gives cyclic Ru complexes which have a four- to six-membered ring in their structure and display very good catalytic activity in homogeneous catalysis. The effect of P-P coordination is obtained by use of diphosphorus donor ligands P(l)-P(2) which are sterically able to form a four- to six-membered ring with the central Ru atom. For the purposes of the present patent application, Ru complexes bearing ferrocenylphosphine ligands having phosphine groups on the different Cp rings have a six-membered ring. The ferrocene unit P-C-Fe-C-P makes available five ring atoms of the ring formed. The numbering of the ring members used here is shown schematically in figure 1. The chiral diphosphorus donor ligand P(l)-P(2) is generally selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphospho- nites and diazaphospholanes. Examples of suitable diphosphorus donor ligands for preparing four-membered cyclic Ru complexes are the ligands of the MiniPhos and Trichickenfootphos families. Examples of suitable diphosphorus donor ligands for preparing five-membered cyclic Ru complexes are the ligands of the families DIPAMP, Norphos, PROPHOS, DuPHOS, Chiraphos, Bis-P* family, DepyPhos (or DeguPhos), RoPhos, CATAXIUM, ButiPhane, (1,2-ethylene)- BinaPhane, (1,2-phenylene)-BinaPhane, Binapine, TangPhos, BPE, BasPhos, MalPhos, Me-KetalPhos, Helmchen ligands, PennPhos, UCAP, Hoge ligands and CNR-Phos. However, the use range of the invention is not restricted to these ligands. Examples of suitable diphosphorus donor ligands for preparing six-membered cyclic Ru complexes are the ligands of the families BDPP (or SKEWPHOS), BPPFOH, MandyPhos, JosiPhos, FerroTANE Me-f-KetalPhos, Ferrocelane, Trifer and (1,1'-ferrocene)-BinaPhane. However, the use range of the invention is not restricted to these ligands. A preferred embodiment of the invention comprises ruthenium complexes having five- or six-membered rings. Preferred ligand systems are the ligands of the DepyPhos (Deguphos) family which form five-membered rings and the Josiphos and Mandyphos ligands which lead to six-membered rings. The diphosphorus donor ligands indicated above can have axial, central and/or planar chirality and are in most cases commercially available. When these ligands are used in the preparative process of the invention, cyclic Ru complexes having a four- to six-membered ring in their structure are obtained. However, other chiral diphosphorus donor ligands are also suitable, as long as they make formation of a four- to six-membered ring possible. The present invention further provides a process for preparing the inventive ruthenium complexes of the types A and B, in which specific Ru starting compounds are reacted with a chiral diphosphorus donor ligand or the ruthenium complex of type A is reacted with a further ligand. The effect of P-P coordination in the ruthenium complexes of the invention is achieved in the present preparative process by use of a specific Ru starting compound in which the central Ru atom is in the oxidation state +11 and which has at least three uncharged ligands LD. It has the following general formula wherein - Ru is in the oxidation state +11, - n is an integer obeying n > 3, - LD is an uncharged ligand, - Z is a n-bonded anionic open pentadienyl ligand and - E" is the anion of an oxo acid or complex acid. The at least three uncharged ligands LD belong to the class of 2-electron doner ligands, for example secondary or tertiary phosphines (ligands of the PR2H or PR3 type, for example triphenylphosphine) or N-heterocyclic carbene ligands (known as NHC ligands). The ligands LD are preferably weakly bound to the central Ru atom. At least two of these ligands are replaced in the reaction with a chiral diphosphorus donor ligand. Examples of suitable ligands LD are ligands from the group consisting of nitriles, isonitriles, alcohols, ethers, amines, acid amides, lactams and sulfones; for example acetonitrile (CH3CN) , diethyl ether (DEE), water (H2O) or acetone. It is also possible to use cyclic ligands such as tetrahydrofuran (THF), dioxane, pyridine, imidazole or thiophene. Mixed systems comprising different types of ligands are also possible. However, solvent ligands from the group consisting of acetonitrile (CH3CN), diethyl ether, water and acetone are preferred. Furthermore, the Ru starting compound has a π-bonded anionic (i.e. singly negatively charged) ligand Z. Ligands Z encompass open (i.e. acyclic) pentadienyl ligands. Such ligands can be substituted or unsubstituted. They have a delocalized n-electron system. The substituted pentadienyl ligands can be monosubstituted, disubstituted or trisubstituted. Preferred substituted pentadienyl ligands Z are 1-methylpentadienyl, 2-methylpentadienyl, 3-phenyl- pentadienyl, 2,4-dimethylpentadienyl or 2,3,4-tri- methylpentadienyl. Closed, cyclic aromatic TC-systems such as substituted or unsubstituted cyclopentadienyl ligands are not suitable as ligands Z. It has been found that such cyclopentadienyl ligands are bound very strongly to the central Ru atom because of the high electron density of the aromatic π-electron system present. This hinders access of reactants during the catalysis reaction, for example in a catalytic hydrogenation. Thus, for example, the coordination of the compound to be hydrogenated to the Ru atom is made difficult in a hydrogenation reaction, as a result of which the corresponding Ru complex has a low reactivity as catalyst. The Ru starting compound used for the process of the invention is present in the form of a cation having a single positive charge and has, as further constituent, E" (the anion of an oxo acid or complex acid) as counterion. Examples of anions E" are HSO4-, CF3SO3", CIO4-, CF3COO-, CH3COO-, BF4-, B(aryl)4-, SbF6- or PF6-. Examples of suitable Ru starting compounds are [Ru(2,4-dimethylpentadienyl) (CH3CN)3]"BF4", [Ru(2,4-di- methylpentadienyl) (H2O)3]+BF4- and [Ru(2,4-dimethylpenta- dienyl) (acetone) 3]+BF4-. The Ru starting compound can firstly be prepared from known, commercially available Ru precursor compounds (e.g. bis(η5-(2, 4-dimethylpenta- dienyl)Ru) by reaction with the appropriate ligand LD according to process steps known from the literature. It has been found that the reaction of the above- described Ru starting compound with the suitable chiral diphosphorus donor ligands (hereinafter referred to as P(l)-P(2) for short) gives the Ru complexes of the invention. The formation of the complex of type A occurs by ligand exchange in the preparative process according to eq. (1): Equation (1): The inventive Ru complex of type A is obtained according to eq. (1). This complex is cationic, i.e. singly positively charged. In the preparation of the complex, the chiral diphosphorus donor ligand is reacted with the above-described Ru starting compound, with at least two of the ligands LD being replaced in the reaction. If the Ru starting compound has more than two ligands LD, the remaining ligands LD stay coordinated to the ruthenium. They can be replaced or eliminated in a subsequent step. This gives the inventive Ru complex of type B. The preparation of the Ru complexes of types A and B is preferably carried out under a protective gas atmosphere using the Schlenk technique and oxygen-free solvents. However, this is not necessary in all cases. To prepare type A, the diphosphorus donor ligands are typically reacted with the Ru starting compound in a suitable solvent at temperatures in the range from -80°C to 80°C, preferably in the range from 20 to 60°C and particularly preferably at room temperature (25°C) , while stirring. Suitable solvents are chlorinated hydrocarbons such as chloroform, methylene chloride, trichloroethane or dichloroethane. However, preference is given to using dipolar, aprotic solvents such as acetone, THF or dioxane. The reaction times are in the range from 1 hour to 48 hours, preferably in the range from 1 hour tc 24 hours. It can be advantageous to use the ligand in a small excess in the preparation of the Ru complexes of type A, with the excess being able to be in the range from 1 to 10 mol-% (based on the Ru starting compound). The subsequent isolation, washing and purification steps are well known to those skilled in the art. To remove solvent residues, the complexes ar,e dried under reduced pressure. The present invention further provides Ru complexes of type B. These complexes are overall electrically neutral and have a negatively charged ligand L2 in addition to the P-P-coordinated chiral diphosphorus donor ligand, the n-bonded anionic pentadienyl ligand Z and, if present, the ligand LD. This ligand Lz is introduced by replacement of one of the ligands LD by an anion, preferably a halide ion (fluoride, chloride, bromide or iodide) or a pseudohalide ion (e.g. CN-, SCN-, cyanate, isocyanate, etc.). The Ru complex of type B is preferably prepared from the complex of type A by ligand exchange, for example by replacement of an acetonitrile molecule by iodide (cf. example 2). Equation (2) describes the replacement of the ligand LD by a negatively charged ligand Lz) : Equation (2): To carry out the reaction according to equation (2), the cationic Ru complex (type A) is reacted in suitable solvents such as chlorinated hydrocarbons (e.g. chloroform, methylene chloride, trichloroethane or dichloroethane), alcohols, ketones (e.g. acetone) or cyclic ethers (e.g. THF or dioxane). However, preference is given to using aqueous solvent mixtures, in particular a mixture of a dipolar, aprotic solvent with deionized water. Here, the cationic Ru complex (type A) is, for example, dissolved in acetone/water (2:1) and reacted with the ligand Lz at temperatures in the range from 0° to 50°C. The ligand Lz is preferably added in the form of a salt M+Lz, for example in the form of an alkali metal halide or ammonium halide. The product generally precipitates and can be separated off. The aqueous solvent mixtures are particularly suitable for industrial syntheses for reasons of environmental protection and occupational hygiene. It has surprisingly been found that the chlorinated hydrocarbons used hitherto can be replaced as solvents without decreases in yield. The inventive Ru complexes of type A and of type B where in each case - Ru is present in the oxidation state +II, - P(l)-P(2) is a chiral diphosphorus donor ligand, - n is an integer which obeys n ≥ 3, - LD is at least one uncharged ligand, - Z is a n-bonded anionic open pentadienyl ligand, - E- is an anion of an oxo acid or complex acid and - Lz is at least one anionic ligand, and the chiral diphosphorus donor ligand P(l)-P(2) has bidentate P-P coordination and forms a four- to six-membered ring with the ruthenium, are effective homogeneous catalysts for the asymmetric hydrogenation of prochiral organic compounds. A shared characteristic of the inventive Ru complexes of types A and B is the presence of the anionic open pentadienyl ligand in the complex. It has surprisingly been found that this gives a higher reactivity of the Ru complexes in catalysis, in particular in asymmetric hydrogenation. The open pentadienyl ligand is presumably easier to destabilize than closed ligand systems such as cyclopentadienyl and cyclooctadienyl, so that it can make available a coordination site for the substrate molecule to be hydrogenated. It has surprisingly been found that the ligands LD and/or Lz also play a very important role. They presumably block a coordination site so that the substrate can coordinate to the metal only in a particular way, as a result of which the enantioselectivity is increased. The inventive Ru complexes of types A and B are therefore used as catalysts for homogeneous asymmetric catalysis, for example for the enantioselective hydrogenation of multiple bonds. For the purposes of the present invention, multiple bonds are double bonds between a carbon atom and a further carbon atom (C=C) or oxygen atom (C=O) or nitrogen atom (C=N). Furthermore, the ruthenium complexes of the invention can also be used as catalysts for other asymmetric reactions. These include C-C, C-O, C-N, C-P, C-Si, C-B or C-halogen coupling reactions. Examples are asymmetric cyclization reactions, asymmetric oligomerizations and asymmetric polymerization reactions. The inventive ruthenium(II) complexes of types A and B are used as defined compounds. In comparison, Ru complexes which are used together with the diphosphorus donor ligands in in-situ processes display poorer catalytic properties. The following examples illustrate the invention without restricting its scope. EXAMPLES Example 1: Preparation of (η5-2,4-dimethylpentadienyl) (CH3CN)- (Josiphos-SL-J212-l)ruthenium(ll) tetrafluoroborate a) Preparation of (η4-2 , 4-dimethylpentadiene-η2- C, H) (η5-2, 4-dimethylpentadienyl) ruthenium tetra- fluoroborate In a 100 ml Schlenk tube provided with a magnetic stirrer, 1.1 g (3.77 mmol) of bis (η5-2,4-dimethylpenta- dienyl) ruthenium (UMICORE, Hanau) are dissolved in 50 ml of diethyl ether. 0.51 ml (3.77 mmol) of a 54% strength HBF4-Et2O solution (from Aldrich) is added dropwise at room temperature over a period of 10 minutes. After the addition is complete, the mixture is allowed to settle and the completeness of precipitation is tested by addition of a further drop of HBF4-Et2O. The supernatant solvent is taken off and the solid is washed twice with diethyl ether. The light-yellow residue is dried under reduced pressure. Yield: 1.43 g (100%). b) Preparation of the acetonitrile complex (T)5- 2, 4-dimethylpentadienyl) (CH3CN)3ruthenium(II) tetrafluoroborate (starting compound) 0.41 g (1.1 mmol) of (η4-2,4-dimethylpentadiene-η2- C,H) (η5-2, 4-dimethylpentadienyl) ruthenium tetrafluoro- borate prepared in step a) are admixed with 10 ml of acetonitrile. The orange solution is stirred for 10 minutes and the solvent is removed under reduced pressure to give an orange solid. Yield: 0.44 g (100%). c) Preparation of (T)5-2,4-dimethylpentadienyl)(CH3CN)- (Josiphos SL J212-1) ruthenium(II) tetrafluoroborate In a 50 ml round-bottomed flask provided with a magnetic stirrer, the acetonitrile complex (η5-2,4-di- methylpentadienyl) (CH3CN) 3ruthenium(II) tetrafluoro- borate is dissolved in 15 ml of methylene chloride and stirred with 200 mg (0.38 mmol) of Josiphos SL-J212-1 (from Solvias, Basle, CH) at room temperature for 6 hours. 50 ml of n-hexane are then added dropwise to the solution. A red-orange solid precipitates and is filtered off. The residual solvent is removed at room temperature under reduced pressure. This gives a product as a mixture of three diastereomers, yield: 95%. The P-P coordination of the ligand (and thus the presence of a 6-membered ring) is demonstrated by the 31P MMR spectrum. Characterization: 31P NMR (CD2Cl2)δ: 10.32 ppm (d, JPP=28.5 Hz), 11.80 ppm (d, JpP=31.0 Hz), 20.10 ppm (d, JPP=29.8 Hz), 75.79 ppm (d, JPP=31.0 Hz), 89.55 ppm (d, JPP=28.5 Hz), 94.75 ppm (d, crPP=29.8 Hz) . d) Use for catalytic hydrogenation The (η5-2, 4-dimethylpentadienyl) (CH3CN) (Josiphos-SL- J212-1)ruthenium(II) tetrafluoroborate complex prepared as described in example 1 is used for the asymmetric hydrogenation of E-2-methyl-2-butenoic acid. The hydrogenation is carried out in an autoclave under 50 bar of hydrogen; solvent: methanol, temperature: 50°C. After a reaction time of 20 hours, the hydrogen pressure is removed. The complex according to the invention gives very good results when used as catalyst for enantioselective catalytic hydrogenation. Example 2 (Josiphos SL-J212-l)ruthenium(II) In a 25 ml round-bottomed flask provided with a magnetic stirrer, the acetonitrile complex (TJ5 - 2, 4-dimethylpentadienyl) (SL-J212-1) (CH3CN)ruthenium(II) tetrafluoroborate prepared as described in example 1b) (1.50 mg, 0.18 mmol) is dissolved in 4 ml of acetone and 2 ml of water and stirred with lithium iodide (LiI, 28.5 mg, 0.21 mmol) at room temperature for 3 hours. The solution is evaporated to dryness at room temperature under reduced pressure. The residue is washed three times with 1 ml of water. This gives the product in the form of a diastereomerically pure compound. Yield: 90%. The P-P coordination of the SL-J-212-1 is demonstrated by the 31P-NMR spectrum. Characterization: 31P NMR (CD2Cl2)δ: 7.51 ppm (d, JPP=35.9 Hz), 84.30 ppm (d, JPP=35.9 Hz). Use for catalytic hydrogenation: The (Josiphos SL-J-212-1)(iodo)ruthenium(II) complex prepared as described in example 2 is used for the asymmetric hydrogenation of E-2-methyl-2-butenoic acid. The complex gives very good results as catalyst for enantioselective catalytic hydrogenation. Example 3 Preparation of (5-2,4-dimethylpentadienyl)(CH3CN)- ((R,R)-DepyPhos)ruthenium(II) tetrafluoroborate In a 50 ml Schlenk tube provided with a magnetic stirrer, the acetonitrile complex (η5-2,4-dimethyl- pentadienyl) (CH3CN)3ruthenium(II) tetraf luoroborate prepared as described in example 1b) is dissolved in 15 ml of methylene chloride and stirred with 25 mg (0.05 mmol) of (R,R) DcpyJThcs {from Digital Speciality Chemicals, Toronto, Canada) at room temperature for half an hour. 50 ml of n-hexane are then added dropwise to the solution. A yellow-orange solid precipitates and is filtered off. The residual solvent is removed at room temperature under reduced pressure. The product is obtained in the form of a diastereomerically pure compound, yield: 98%. The P-P coordination of the ligand (and thus the presence of a 5-membered ring) is demonstrated by the 31P NMR spectrum. Use for catalytic hydrogenation: The complex prepared as described in example 3 is used for the asymmetric hydrogenation of E-2-methyl- 2-butenoic acid. The hydrogenation is carried out in an autoclave under 50 bar of hydrogen; solvent: methanol, temperature: 50°C. After a reaction time of 20 hours, the hydrogen pressure is removed. The complex gives very good results as catalyst for enantioselective catalytic hydrogenation. We claim: 1. A ruthenium complex having a chiral diphosphorus donor ligand for homogeneous catalysis having the general formula or wherein - ruthenium is present in the oxidation state +11, - P(1)-P(2) is a chiral diphosphorus donor ligand, - n is an integer which obeys n > 3, - LD is at least one uncharged ligand, - Z is a π-bonded anionic open pentadienyl ligand, - E- is an anion of an oxo acid or complex acid and - Lz is at least one anionic ligand, and the chiral diphosphorus donor ligand P(1)-P(2) has bidentate P-P coordination and forms a four- to six-membered ring with the ruthenium. 2. The ruthenium complex as claimed in claim 1, wherein the chiral diphosphorus donor ligand P(1)-P(2) is selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphosphonites and diazaphospholanes. 3. The ruthenium complex as claimed in claim 1 or 2, wherein a four-membered ring is present and the chiral diphosphorus donor ligand P(1)-P(2) is selected from the group consisting of MiniPhos and Trichickenfootphos ligands. 4. The ruthenium complex as claimed in claim 1 or 2, wherein a five-membered ring is present and the chiral diphosphorus donor ligand P(1)-P(2) is selected from the group consisting of DIPAMP, Norphos, PROPHOS, DuPHOS, Chiraphos, Bis-P* family, DepyPhos (or DeguPhos), RoPhos, CATAXIUM, ButiPhane, (1,2-ethylene)-BinaPhane, (1,2-phenylene)-BinaPhane, Binapine, TangPhos, BPE, BasPhos, MalPhos, Me-KetalPhos, Helmchen ligands, PennPhos, UCAP, Hoge ligands and CNR-Phos ligands. 5. The ruthenium complex as claimed in claim 1 or 2, wherein a six-membered ring is present and the chiral diphosphorus donor ligand P(1)-P(2) is selected from the group consisting of BDPP (or SKEWPHOS), BPPFOH, MandyPhos, JosiPhos, FerroTANE Me-f-KetalPhos, Ferrocelane, Trifer and (1,1'-ferrocene)-BinaPhane ligands. 6. The ruthenium complex as claimed in any of claims 1 to 5, wherein LD is an uncharged 2-electron donor Iigand and is a solvent ligand from the group consisting of acetonitrile (CH3CN), diethyl ether, water, acetone, tetrahydrofuran, dixane, pyridine, imidazole and thiophene. 7. The ruthenium complex as claimed in any of claims 1 to 6, wherein Z is a substituted open pentadienyl ligand and is 1-methylpentadienyl, 2,4-dimethylpentadienyl or 2,3,4-trimethylpenta- dienyl. 8. The ruthenium complex as claimed in any of claims 1 to 7, wherein Z is 2,4-dimethylpenta- dienyl. 9. The ruthenium complex as claimed in any of claims 1 to 8, wherein E- is an anion from the group consisting of HSO4-, CF3SO3-, CF3CO2-, CH3CO2-, CIO4, BF4-, B(aryl)4-, SbF6- or PF6-. 10. The ruthenium complex as claimed in any of claims 1 to 9, wherein Lz is at least one anionic ligand from the group consisting of halides and pseudohalides. 11. The ruthenium complex as claimed in any of claims 1 to 10, wherein Lz is iodide, Z is 2, 4-dimethylpentadienyl and E" is BF4-. 12. A process for preparing the ruthenium complex (type A) as claimed in any of claims 1 to 9, wherein an Ru starting compound of the general formula wherein - Ru is in the oxidation state +II, - n is an integer obeying n > 3, - LD is an uncharged ligand, - Z is a π-bonded anionic open pentadienyl ligand and - E- is an anion of an oxo acid or complex acid, is reacted with a chiral diphosphorus donor ligand P(1)-P(2). 13.. The process as claimed in claim 12, wherein the chiral diphosphorus donor ligand P(1)-P(2) forms a four- to six-membered ring with the ruthenium. 14. The process as claimed in claim 12 or 13, wherein the chiral diphosphorus donor ligand P(1)-P(2) is selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphosphonites and diazaphospholanes. 15. The process as claimed in any of claims 12 to 14, wherein the chiral diphosphorus donor ligand P(l)-P(2) forms a four-membered ring with the ruthenium and is selected from the group consisting of MiniPhos and Trichickenfootphos ligands. 16. The process as claimed in any of claims 12 to 14, wherein the chiral diphosphorus donor ligand P(l)-P(2) forms a five-membered ring with the ruthenium and is selected from the group consisting of DIPAMP, Norphos, PROPHOS, DuPHOS, Chiraphos, Bis-P* family, DepyPhos (or DeguPhos), RoPhos, CATAXIUM, ButiPhane, (1,2-ethylene)- BinaPhane, (1, 2-phenylene)-BinaPhane, Binapine, TangPhos, BPE, BasPhos, MalPhos, Me-KetalPhos, Helmchen ligands, PennPhos, UCAP, Hoge ligands and CNR-Phos ligands. 17. The process as claimed in any of claims 12 to 14, wherein the chiral diphosphorus donor ligand P(l)-P(2) forms a six-membered ring with the ruthenium and is selected from the group consisting of BDPP (or SKEWPHOS) BPPFOH, MandyPhos, JosiPhos, FerroTANE Me-f-KetalPhos, Ferrocelane, Trifer and (1,1'-ferrocene)-BinaPhane ligands. 18.. The process as claimed in any of claims 12 to 17, wherein LD is at least one uncharged 2-electron donor ligand and is a solvent selected from the group consisting of acetonitrile (CH3CN) , diethyl ether, water, acetone, tetrahydrofuran, dioxane, pyridine, imidazole and thiophene. 19. The process as claimed in any of claims 12 to 18, wherein Z is a substituted open pentadienyl ligand and is 1-methylpentadienyl, 2,4-dimethylpenta- dienyl or 2,3,4-trimethylpentadienyl. 20. The process as claimed in any of claims 12 to 19, wherein E- is an anion from the group consisting of HSO4-, CF3SO3-, CF3CO2-, CH3CO2-, CIO4-, BF4-, B(aryl)4- , SbF6- or PF6-. 21. The process as claimed in any of claims 12 to 20, wherein dipolar, aprotic solvents such as acetone, THF or dioxane are used as solvents. 22. A process for preparing the ruthenium complex (type B) as claimed in any of claims 1 to 11, wherein the cationic ruthenium complex of type A is reacted with a negatively charged ligand Lz from the group consisting of halides and pseudohalides. 23. The process as claimed in claim 22, wherein an aqueous solvent mixture, in particular a mixture of a dipolar, aprotic solvent with water, is used as solvent 24. The use of the ruthenium complexes as claimed in any of claims 1 to 11 as catalysts for homogeneous asymmetric catalysis, in particular for the homogeneous asymmetric catalytic hydrogenation of organic compounds. 25. The use of the ruthenium complexes as claimed in any of claims 1 to 11 as catalysts for the enantioselective hydrogenation of C=C, C=0 or C=N multiple bonds. The invention relates to ruthenium complexes which have a chiral diphosphorus donor ligand and in which the ruthenium has the oxidation state (+11) and the chiral diphosphorus donor ligand has bidentate P-P coordination to the ruthenium. The ruthenium complexes are present in two forms (cationic type A and uncharged type B), are cyclic and have a four- to six-membered ring incorporating the diphosphorus donor ligand. The chiral diphosphorus donor ligands are selected from the group consisting of diphosphines, diphospholanes, diphosphites, diphosphonites and diazaphospholanes. Furthermore, processes for preparing the ruthenium complexes of types A and B, which are based on ligand exchange reactions, are described. The Ru complexes are used as catalysts for homogeneous asymmetric catalysis for preparing organic compounds.

Full Text

Ruthenium complexes having (P-P)-coordinated
disphosphorus donor ligands and processes
for preparing them
Description
The present invention relates to ruthenium complexes
for homogeneous catalysis, in particular P-P-
coordinated cyclic ruthenium complexes having chiral
diphosphorus donor ligands. The invention further
provides processes for preparing them and also the use
of these complexes as catalysts for homogeneous
catalysis, in particular for enantioselective
hydrogenation.
Chiral diphosphorus donor ligands have been found to be
valuable ligands for catalytically active metal
complexes which are used in homogeneous catalysis for
the enantioselective hydrogenation of organic
compounds. Fields of use are the preparation of
intermediates or active compounds, for example
pharmaceuticals, pesticides, flavors or fragrances.
In enantioselective hydrogenation, these diphosphorus
donor ligands are used together with suitable noble
metal complexes.
Organometallic Ru compounds used in these
hydrogenations are, for example, [Ru(COD)Y2]x,
[Ru(NBD)Y2]x, [Ru(aromatic)Y2]x or [Ru(COD)2-methyl-
allyl)2] (where X = 2; Y = halide, COD = 1,5-cyclo-
octadiene, NBD = norbornadiene, aromatic = for example
p-cumene or another benzene derivative).
EP 1622920B1 discloses transition metal complexes
having ferrocenyldiphosphine ligands. Complexes having

specific P-P coordination of the phosphine ligands are
Ru complexes having (P-P)-coordinated diphosphorus
donor ligands are known from the literature.
M. Sato and M. Asai (J. of Organometallic Chemistry 508
(1996) pp. 121-127) describe permethylcyclopentadienyl-
Ru'(ll) complexes having dppf, BINAP and DIOP ligands.
As a result of the permethylcyclopentadienyl radical,
these complexes are very stable; use for catalytic
hydrogenation is not described.
C. Standfest-Hauser, C. Slugovc et al. (J. Chem. Soc.
Dalton Trans., 2001, pp. 2989-2995) report cyclic
Ru(II) semisandwich complexes which likewise have a
cyclopentadienyl ligand and also chelating phosphino-
amine ligands. These complexes contain a cyclopenta-
dienyl ligand ("Cp ligand") and are not very suitable
for use as catalysts for homogeneous asymmetric
hydrogenation. They are normally used in a specific
catalysis reaction (namely transfer hydrogenation),
with the Cp ligand stabilizing the catalyst and having
to be coordinated to the metal during catalysis.
J.B. Hoke et al. (J. of Organomet. Chem., 1993, 455,
pp. 193-196) describe ruthenium complexes in which
BINAP ligands form a seven-member ed ring with the Ru.
The complexes contain one cyclopentadienyl group. They
are very stable but display little activity in
catalytic hydrogenation and some of them are
unselective since the Cp ligand is bound very strongly
to the metal.
P.S. Pregosin et al. (Organometallics, 1997, 16, pp.
537-543) have reported a ruthenium complex which bears
the MeO-BIPHEP ligand and additionally has a cycloocta-

dienyl radical. The complex can be prepared only by
means of a complicated process and is very air- and
moisture-sensitive. Use for catalytic hydrogenation is
not described. A similar complex bearing the BINAP
ligand has been described by S.H. Bergens et al.
(Organometallics, 2004, 23, pp. 4564-4568). An aceto-
nitrile complex was isolated in the synthesis and this
is not very active in catalysis.
A. Salzer et al. (Organometallics, 2000, 19, pp. 5471-
5476) have reported the preparation of a seven-membered
BINAP-ruthenium complex from a (bispentadienyl)Ru
compound as starting complex.
D.A. Dobbs et al. (Angew. Chem. 2000, volume 112, pp.
2080-2083) describe a ruthenium-containing precatalyst
having a P-P-coordinated DuPhos ligand. The cyclic
compound is an Ru hybrid species and has an uncharged
cyclooctatrienyl ligand. It is very sensitive and was
prepared in a glove box (inert gas: Ar containing
very suitable for industrial use.
WO 00/37478 describes transition metal complexes which
have a metal atom of transition group 7 or 8 and in
which both P atoms of a diphosphine ligand are
simultaneously coordinated to the central atom, but the
complexes are neither isolated nor characterized. No
preparative method is described; rather, the complexes
are generated by combining the ligands and the
appropriate transition metal salts in the reaction
solvent shortly before use ("in-situ"). These in-situ
processes are prior art. Few studies have hitherto been
carried out on the structure of the metal complexes
generated in-situ; the corresponding complexes were not
isolated but instead used directly in the reaction
mixture for homogeneous catalysis, in particular for

catalytic hydrogenation. The mechanistic studies are
carried out using model systems which do not correspond
to the real active catalytic species.
US 6,455,460 describes a ruthenium catalyst obtainable
by a process which comprises putting together an
appropriate Ru(II) complex, a chelating diphosphine and
an acid comprising an non-coordinating anion. The
reaction is performed under an oxygen-free atmosphere.
Disadvantages of the catalytic hydrogenation processes
described hitherto and the catalysts used therein are,
in particular, the low reactivity, the low
enantioselectivities and a high consumption of noble
metal-containing catalyst, i.e. a low
"substrate/catalyst" (S/C) ratio. Furthermore, long
hydrogenation times are required. In addition, many of
the complexes described are difficult to synthesize,
are air-sensitive and are not very suitable for
industrial use.
It was therefore an object of the present invention to
provide improved catalysts for homogeneous, asymmetric
hydrogenation which overcome the abovementioned
disadvantages. A further object was to provide suitable
processes for preparing the catalysts of the invention.
In particular, these processes should be able to be
used in industry and be environmentally friendly and
inexpensive.
This object is achieved by the provision of the
ruthenium complexes of the types A and B as claimed in
claim 1 of the invention. Furthermore, processes for
preparing the inventive complexes of types A and B are
provided in claims 12 and 22. Preferred embodiments of
the complexes and the processes are described in the
respective dependent claims.

The present invention describes ruthenium complexes
having a chirai diphosphorus donor iigand of the
P(1)-P(2) type for homogeneous catalysis. The complexes
are of two different types (type A and type B) , with
the ruthenium having the oxidation state +II and the
diphosphorus donor ligands displaying bidentate P-P
coordination to the Ru. The ruthenium complexes of the
invention are cyclic and together with the diphosphorus
donor ligand have a four- to six-membered ring.
In the search for well-defined Ru complexes having
these chiral diphosphorus donor ligands, it has
surprisingly been found that simultaneous coordination
of both P atoms of the diphosphorus donor ligands to a
central Ru atom can be achieved under particular
conditions. This gives cyclic Ru complexes which have a
four- to six-membered ring in their structure and
display very good catalytic activity in homogeneous
catalysis.
The effect of P-P coordination is obtained by use of
diphosphorus donor ligands P(l)-P(2) which are
sterically able to form a four- to six-membered ring
with the central Ru atom. For the purposes of the
present patent application, Ru complexes bearing
ferrocenylphosphine ligands having phosphine groups on
the different Cp rings have a six-membered ring. The
ferrocene unit P-C-Fe-C-P makes available five ring
atoms of the ring formed. The numbering of the ring
members used here is shown schematically in figure 1.

The chiral diphosphorus donor ligand P(l)-P(2) is
generally selected from the group consisting of
diphosphines, diphospholanes, diphosphites, diphospho-
nites and diazaphospholanes.
Examples of suitable diphosphorus donor ligands for
preparing four-membered cyclic Ru complexes are the
ligands of the MiniPhos and Trichickenfootphos
families.
Examples of suitable diphosphorus donor ligands for
preparing five-membered cyclic Ru complexes are the
ligands of the families DIPAMP, Norphos, PROPHOS,
DuPHOS, Chiraphos, Bis-P* family, DepyPhos (or
DeguPhos), RoPhos, CATAXIUM, ButiPhane, (1,2-ethylene)-
BinaPhane, (1,2-phenylene)-BinaPhane, Binapine,
TangPhos, BPE, BasPhos, MalPhos, Me-KetalPhos, Helmchen
ligands, PennPhos, UCAP, Hoge ligands and CNR-Phos.
However, the use range of the invention is not
restricted to these ligands.
Examples of suitable diphosphorus donor ligands for
preparing six-membered cyclic Ru complexes are the
ligands of the families BDPP (or SKEWPHOS), BPPFOH,
MandyPhos, JosiPhos, FerroTANE Me-f-KetalPhos,
Ferrocelane, Trifer and (1,1'-ferrocene)-BinaPhane.
However, the use range of the invention is not
restricted to these ligands.
A preferred embodiment of the invention comprises
ruthenium complexes having five- or six-membered rings.
Preferred ligand systems are the ligands of the
DepyPhos (Deguphos) family which form five-membered
rings and the Josiphos and Mandyphos ligands which lead
to six-membered rings.

The diphosphorus donor ligands indicated above can have
axial, central and/or planar chirality and are in most
cases commercially available. When these ligands are
used in the preparative process of the invention,
cyclic Ru complexes having a four- to six-membered ring
in their structure are obtained. However, other chiral
diphosphorus donor ligands are also suitable, as long
as they make formation of a four- to six-membered ring
possible.
The present invention further provides a process for
preparing the inventive ruthenium complexes of the
types A and B, in which specific Ru starting compounds
are reacted with a chiral diphosphorus donor ligand or
the ruthenium complex of type A is reacted with a
further ligand.
The effect of P-P coordination in the ruthenium
complexes of the invention is achieved in the present
preparative process by use of a specific Ru starting
compound in which the central Ru atom is in the
oxidation state +11 and which has at least three
uncharged ligands LD.
It has the following general formula

wherein
- Ru is in the oxidation state +11,
- n is an integer obeying n > 3,
- LD is an uncharged ligand,
- Z is a n-bonded anionic open pentadienyl ligand
and
- E" is the anion of an oxo acid or complex acid.

The at least three uncharged ligands LD belong to the
class of 2-electron doner ligands, for example
secondary or tertiary phosphines (ligands of the PR2H or
PR3 type, for example triphenylphosphine) or
N-heterocyclic carbene ligands (known as NHC ligands).
The ligands LD are preferably weakly bound to the
central Ru atom. At least two of these ligands are
replaced in the reaction with a chiral diphosphorus
donor ligand. Examples of suitable ligands LD are
ligands from the group consisting of nitriles,
isonitriles, alcohols, ethers, amines, acid amides,
lactams and sulfones; for example acetonitrile (CH3CN) ,
diethyl ether (DEE), water (H2O) or acetone. It is also
possible to use cyclic ligands such as tetrahydrofuran
(THF), dioxane, pyridine, imidazole or thiophene. Mixed
systems comprising different types of ligands are also
possible. However, solvent ligands from the group
consisting of acetonitrile (CH3CN), diethyl ether, water
and acetone are preferred.
Furthermore, the Ru starting compound has a π-bonded
anionic (i.e. singly negatively charged) ligand Z.
Ligands Z encompass open (i.e. acyclic) pentadienyl
ligands. Such ligands can be substituted or
unsubstituted. They have a delocalized n-electron
system. The substituted pentadienyl ligands can be
monosubstituted, disubstituted or trisubstituted.
Preferred substituted pentadienyl ligands Z are
1-methylpentadienyl, 2-methylpentadienyl, 3-phenyl-
pentadienyl, 2,4-dimethylpentadienyl or 2,3,4-tri-
methylpentadienyl.
Closed, cyclic aromatic TC-systems such as substituted
or unsubstituted cyclopentadienyl ligands are not
suitable as ligands Z. It has been found that such
cyclopentadienyl ligands are bound very strongly to the

central Ru atom because of the high electron density of
the aromatic π-electron system present. This hinders
access of reactants during the catalysis reaction, for
example in a catalytic hydrogenation. Thus, for
example, the coordination of the compound to be
hydrogenated to the Ru atom is made difficult in a
hydrogenation reaction, as a result of which the
corresponding Ru complex has a low reactivity as
catalyst.
The Ru starting compound used for the process of the
invention is present in the form of a cation having a
single positive charge and has, as further constituent,
E" (the anion of an oxo acid or complex acid) as
counterion. Examples of anions E" are HSO4-, CF3SO3",
CIO4-, CF3COO-, CH3COO-, BF4-, B(aryl)4-, SbF6- or PF6-.
Examples of suitable Ru starting compounds are
[Ru(2,4-dimethylpentadienyl) (CH3CN)3]"BF4", [Ru(2,4-di-
methylpentadienyl) (H2O)3]+BF4- and [Ru(2,4-dimethylpenta-
dienyl) (acetone) 3]+BF4-. The Ru starting compound can
firstly be prepared from known, commercially available
Ru precursor compounds (e.g. bis(η5-(2, 4-dimethylpenta-
dienyl)Ru) by reaction with the appropriate ligand LD
according to process steps known from the literature.
It has been found that the reaction of the above-
described Ru starting compound with the suitable chiral
diphosphorus donor ligands (hereinafter referred to as
P(l)-P(2) for short) gives the Ru complexes of the
invention. The formation of the complex of type A
occurs by ligand exchange in the preparative process
according to eq. (1):

Equation (1):

The inventive Ru complex of type A is obtained
according to eq. (1). This complex is cationic, i.e.
singly positively charged. In the preparation of the
complex, the chiral diphosphorus donor ligand is
reacted with the above-described Ru starting compound,
with at least two of the ligands LD being replaced in
the reaction. If the Ru starting compound has more than
two ligands LD, the remaining ligands LD stay
coordinated to the ruthenium. They can be replaced or
eliminated in a subsequent step. This gives the
inventive Ru complex of type B.
The preparation of the Ru complexes of types A and B is
preferably carried out under a protective gas
atmosphere using the Schlenk technique and oxygen-free
solvents. However, this is not necessary in all cases.
To prepare type A, the diphosphorus donor ligands are
typically reacted with the Ru starting compound in a
suitable solvent at temperatures in the range from
-80°C to 80°C, preferably in the range from 20 to 60°C
and particularly preferably at room temperature (25°C) ,
while stirring.
Suitable solvents are chlorinated hydrocarbons such as
chloroform, methylene chloride, trichloroethane or
dichloroethane. However, preference is given to using
dipolar, aprotic solvents such as acetone, THF or
dioxane. The reaction times are in the range from

1 hour to 48 hours, preferably in the range from 1 hour
tc 24 hours. It can be advantageous to use the ligand
in a small excess in the preparation of the Ru
complexes of type A, with the excess being able to be
in the range from 1 to 10 mol-% (based on the Ru
starting compound). The subsequent isolation, washing
and purification steps are well known to those skilled
in the art. To remove solvent residues, the complexes
ar,e dried under reduced pressure.
The present invention further provides Ru complexes of
type B. These complexes are overall electrically
neutral and have a negatively charged ligand L2 in
addition to the P-P-coordinated chiral diphosphorus
donor ligand, the n-bonded anionic pentadienyl ligand Z
and, if present, the ligand LD. This ligand Lz is
introduced by replacement of one of the ligands LD by an
anion, preferably a halide ion (fluoride, chloride,
bromide or iodide) or a pseudohalide ion (e.g. CN-,
SCN-, cyanate, isocyanate, etc.).
The Ru complex of type B is preferably prepared from
the complex of type A by ligand exchange, for example
by replacement of an acetonitrile molecule by iodide
(cf. example 2). Equation (2) describes the replacement
of the ligand LD by a negatively charged ligand Lz) :
Equation (2):

To carry out the reaction according to equation (2),
the cationic Ru complex (type A) is reacted in suitable

solvents such as chlorinated hydrocarbons (e.g.
chloroform, methylene chloride, trichloroethane or
dichloroethane), alcohols, ketones (e.g. acetone) or
cyclic ethers (e.g. THF or dioxane). However,
preference is given to using aqueous solvent mixtures,
in particular a mixture of a dipolar, aprotic solvent
with deionized water. Here, the cationic Ru complex
(type A) is, for example, dissolved in acetone/water
(2:1) and reacted with the ligand Lz at temperatures in
the range from 0° to 50°C. The ligand Lz is preferably
added in the form of a salt M+Lz, for example in the
form of an alkali metal halide or ammonium halide. The
product generally precipitates and can be separated
off.
The aqueous solvent mixtures are particularly suitable
for industrial syntheses for reasons of environmental
protection and occupational hygiene. It has
surprisingly been found that the chlorinated
hydrocarbons used hitherto can be replaced as solvents
without decreases in yield.
The inventive Ru complexes of type A

and of type B

where in each case
- Ru is present in the oxidation state +II,

- P(l)-P(2) is a chiral diphosphorus donor ligand,
- n is an integer which obeys n ≥ 3,
- LD is at least one uncharged ligand,
- Z is a n-bonded anionic open pentadienyl ligand,
- E- is an anion of an oxo acid or complex acid and
- Lz is at least one anionic ligand,
and the chiral diphosphorus donor ligand P(l)-P(2)
has bidentate P-P coordination and forms a four-
to six-membered ring with the ruthenium,
are effective homogeneous catalysts for the asymmetric
hydrogenation of prochiral organic compounds.
A shared characteristic of the inventive Ru complexes
of types A and B is the presence of the anionic open
pentadienyl ligand in the complex. It has surprisingly
been found that this gives a higher reactivity of the
Ru complexes in catalysis, in particular in asymmetric
hydrogenation. The open pentadienyl ligand is
presumably easier to destabilize than closed ligand
systems such as cyclopentadienyl and cyclooctadienyl,
so that it can make available a coordination site for
the substrate molecule to be hydrogenated. It has
surprisingly been found that the ligands LD and/or Lz
also play a very important role. They presumably block
a coordination site so that the substrate can
coordinate to the metal only in a particular way, as a
result of which the enantioselectivity is increased.
The inventive Ru complexes of types A and B are
therefore used as catalysts for homogeneous asymmetric
catalysis, for example for the enantioselective
hydrogenation of multiple bonds. For the purposes of
the present invention, multiple bonds are double bonds
between a carbon atom and a further carbon atom (C=C)
or oxygen atom (C=O) or nitrogen atom (C=N).

Furthermore, the ruthenium complexes of the invention
can also be used as catalysts for other asymmetric
reactions. These include C-C, C-O, C-N, C-P, C-Si, C-B
or C-halogen coupling reactions. Examples are
asymmetric cyclization reactions, asymmetric
oligomerizations and asymmetric polymerization
reactions.
The inventive ruthenium(II) complexes of types A and B
are used as defined compounds. In comparison, Ru
complexes which are used together with the diphosphorus
donor ligands in in-situ processes display poorer
catalytic properties.
The following examples illustrate the invention without
restricting its scope.

EXAMPLES
Example 1:
Preparation of (η5-2,4-dimethylpentadienyl) (CH3CN)-
(Josiphos-SL-J212-l)ruthenium(ll) tetrafluoroborate
a) Preparation of (η4-2 , 4-dimethylpentadiene-η2-
C, H) (η5-2, 4-dimethylpentadienyl) ruthenium tetra-
fluoroborate
In a 100 ml Schlenk tube provided with a magnetic
stirrer, 1.1 g (3.77 mmol) of bis (η5-2,4-dimethylpenta-
dienyl) ruthenium (UMICORE, Hanau) are dissolved in
50 ml of diethyl ether. 0.51 ml (3.77 mmol) of a 54%
strength HBF4-Et2O solution (from Aldrich) is added
dropwise at room temperature over a period of
10 minutes. After the addition is complete, the mixture
is allowed to settle and the completeness of
precipitation is tested by addition of a further drop
of HBF4-Et2O. The supernatant solvent is taken off and
the solid is washed twice with diethyl ether. The
light-yellow residue is dried under reduced pressure.
Yield: 1.43 g (100%).
b) Preparation of the acetonitrile complex (T)5-
2, 4-dimethylpentadienyl) (CH3CN)3ruthenium(II)
tetrafluoroborate (starting compound)
0.41 g (1.1 mmol) of (η4-2,4-dimethylpentadiene-η2-
C,H) (η5-2, 4-dimethylpentadienyl) ruthenium tetrafluoro-
borate prepared in step a) are admixed with 10 ml of
acetonitrile. The orange solution is stirred for
10 minutes and the solvent is removed under reduced
pressure to give an orange solid. Yield: 0.44 g (100%).

c) Preparation of (T)5-2,4-dimethylpentadienyl)(CH3CN)-
(Josiphos SL J212-1) ruthenium(II) tetrafluoroborate
In a 50 ml round-bottomed flask provided with a
magnetic stirrer, the acetonitrile complex (η5-2,4-di-
methylpentadienyl) (CH3CN) 3ruthenium(II) tetrafluoro-
borate is dissolved in 15 ml of methylene chloride and
stirred with 200 mg (0.38 mmol) of Josiphos SL-J212-1
(from Solvias, Basle, CH) at room temperature for
6 hours. 50 ml of n-hexane are then added dropwise to
the solution. A red-orange solid precipitates and is
filtered off. The residual solvent is removed at room
temperature under reduced pressure. This gives a
product as a mixture of three diastereomers, yield:
95%. The P-P coordination of the ligand (and thus the
presence of a 6-membered ring) is demonstrated by the
31P MMR spectrum.
Characterization:
31P NMR (CD2Cl2)δ: 10.32 ppm (d, JPP=28.5 Hz), 11.80 ppm
(d, JpP=31.0 Hz), 20.10 ppm (d, JPP=29.8 Hz), 75.79 ppm
(d, JPP=31.0 Hz), 89.55 ppm (d, JPP=28.5 Hz), 94.75 ppm
(d, crPP=29.8 Hz) .
d) Use for catalytic hydrogenation
The (η5-2, 4-dimethylpentadienyl) (CH3CN) (Josiphos-SL-
J212-1)ruthenium(II) tetrafluoroborate complex prepared
as described in example 1 is used for the asymmetric
hydrogenation of E-2-methyl-2-butenoic acid. The
hydrogenation is carried out in an autoclave under
50 bar of hydrogen; solvent: methanol, temperature:
50°C. After a reaction time of 20 hours, the hydrogen
pressure is removed. The complex according to the
invention gives very good results when used as catalyst
for enantioselective catalytic hydrogenation.

Example 2
(Josiphos SL-J212-l)ruthenium(II)
In a 25 ml round-bottomed flask provided with a
magnetic stirrer, the acetonitrile complex (TJ5 -
2, 4-dimethylpentadienyl) (SL-J212-1) (CH3CN)ruthenium(II)
tetrafluoroborate prepared as described in example 1b)
(1.50 mg, 0.18 mmol) is dissolved in 4 ml of acetone and
2 ml of water and stirred with lithium iodide (LiI,
28.5 mg, 0.21 mmol) at room temperature for 3 hours.
The solution is evaporated to dryness at room
temperature under reduced pressure. The residue is
washed three times with 1 ml of water. This gives the
product in the form of a diastereomerically pure
compound. Yield: 90%. The P-P coordination of the
SL-J-212-1 is demonstrated by the 31P-NMR spectrum.
Characterization:
31P NMR (CD2Cl2)δ: 7.51 ppm (d, JPP=35.9 Hz), 84.30 ppm
(d, JPP=35.9 Hz).
Use for catalytic hydrogenation:
The (Josiphos SL-J-212-1)(iodo)ruthenium(II) complex
prepared as described in example 2 is used for the
asymmetric hydrogenation of E-2-methyl-2-butenoic acid.
The complex gives very good results as catalyst for
enantioselective catalytic hydrogenation.
Example 3
Preparation of (5-2,4-dimethylpentadienyl)(CH3CN)-
((R,R)-DepyPhos)ruthenium(II) tetrafluoroborate
In a 50 ml Schlenk tube provided with a magnetic
stirrer, the acetonitrile complex (η5-2,4-dimethyl-
pentadienyl) (CH3CN)3ruthenium(II) tetraf luoroborate
prepared as described in example 1b) is dissolved in

15 ml of methylene chloride and stirred with 25 mg
(0.05 mmol) of (R,R) DcpyJThcs {from Digital Speciality
Chemicals, Toronto, Canada) at room temperature for
half an hour. 50 ml of n-hexane are then added dropwise
to the solution. A yellow-orange solid precipitates and
is filtered off. The residual solvent is removed at
room temperature under reduced pressure. The product is
obtained in the form of a diastereomerically pure
compound, yield: 98%. The P-P coordination of the
ligand (and thus the presence of a 5-membered ring) is
demonstrated by the 31P NMR spectrum.
Use for catalytic hydrogenation:
The complex prepared as described in example 3 is used
for the asymmetric hydrogenation of E-2-methyl-
2-butenoic acid. The hydrogenation is carried out in an
autoclave under 50 bar of hydrogen; solvent: methanol,
temperature: 50°C. After a reaction time of 20 hours,
the hydrogen pressure is removed. The complex gives
very good results as catalyst for enantioselective
catalytic hydrogenation.

We claim:
1. A ruthenium complex having a chiral diphosphorus
donor ligand for homogeneous catalysis having the
general formula

or

wherein
- ruthenium is present in the oxidation state +11,
- P(1)-P(2) is a chiral diphosphorus donor
ligand,
- n is an integer which obeys n > 3,
- LD is at least one uncharged ligand,
- Z is a π-bonded anionic open pentadienyl
ligand,
- E- is an anion of an oxo acid or complex acid
and
- Lz is at least one anionic ligand,
and the chiral diphosphorus donor ligand P(1)-P(2)
has bidentate P-P coordination and forms a four-
to six-membered ring with the ruthenium.

2. The ruthenium complex as claimed in claim 1,
wherein the chiral diphosphorus donor ligand
P(1)-P(2) is selected from the group consisting of
diphosphines, diphospholanes, diphosphites,
diphosphonites and diazaphospholanes.
3. The ruthenium complex as claimed in claim 1 or 2,
wherein a four-membered ring is present and the
chiral diphosphorus donor ligand P(1)-P(2) is
selected from the group consisting of MiniPhos and
Trichickenfootphos ligands.
4. The ruthenium complex as claimed in claim 1 or 2,
wherein a five-membered ring is present and the
chiral diphosphorus donor ligand P(1)-P(2) is
selected from the group consisting of DIPAMP,
Norphos, PROPHOS, DuPHOS, Chiraphos, Bis-P*
family, DepyPhos (or DeguPhos), RoPhos, CATAXIUM,
ButiPhane, (1,2-ethylene)-BinaPhane,
(1,2-phenylene)-BinaPhane, Binapine, TangPhos,
BPE, BasPhos, MalPhos, Me-KetalPhos, Helmchen
ligands, PennPhos, UCAP, Hoge ligands and CNR-Phos
ligands.
5. The ruthenium complex as claimed in claim 1 or 2,
wherein a six-membered ring is present and the
chiral diphosphorus donor ligand P(1)-P(2) is
selected from the group consisting of BDPP (or
SKEWPHOS), BPPFOH, MandyPhos, JosiPhos, FerroTANE
Me-f-KetalPhos, Ferrocelane, Trifer and
(1,1'-ferrocene)-BinaPhane ligands.
6. The ruthenium complex as claimed in any of
claims 1 to 5, wherein LD is an uncharged
2-electron donor Iigand and is a solvent ligand
from the group consisting of acetonitrile (CH3CN),

diethyl ether, water, acetone, tetrahydrofuran,
dixane, pyridine, imidazole and thiophene.
7. The ruthenium complex as claimed in any of
claims 1 to 6, wherein Z is a substituted open
pentadienyl ligand and is 1-methylpentadienyl,
2,4-dimethylpentadienyl or 2,3,4-trimethylpenta-
dienyl.
8. The ruthenium complex as claimed in any of
claims 1 to 7, wherein Z is 2,4-dimethylpenta-
dienyl.
9. The ruthenium complex as claimed in any of
claims 1 to 8, wherein E- is an anion from the
group consisting of HSO4-, CF3SO3-, CF3CO2-, CH3CO2-,
CIO4, BF4-, B(aryl)4-, SbF6- or PF6-.
10. The ruthenium complex as claimed in any of
claims 1 to 9, wherein Lz is at least one anionic
ligand from the group consisting of halides and
pseudohalides.
11. The ruthenium complex as claimed in any of
claims 1 to 10, wherein Lz is iodide, Z is
2, 4-dimethylpentadienyl and E" is BF4-.
12. A process for preparing the ruthenium complex
(type A) as claimed in any of claims 1 to 9,
wherein an Ru starting compound of the general
formula

wherein
- Ru is in the oxidation state +II,
- n is an integer obeying n > 3,
- LD is an uncharged ligand,

- Z is a π-bonded anionic open pentadienyl ligand
and
- E- is an anion of an oxo acid or complex acid,
is reacted with a chiral diphosphorus donor ligand
P(1)-P(2).
13.. The process as claimed in claim 12, wherein the
chiral diphosphorus donor ligand P(1)-P(2) forms a
four- to six-membered ring with the ruthenium.
14. The process as claimed in claim 12 or 13, wherein
the chiral diphosphorus donor ligand P(1)-P(2) is
selected from the group consisting of
diphosphines, diphospholanes, diphosphites,
diphosphonites and diazaphospholanes.
15. The process as claimed in any of claims 12 to 14,
wherein the chiral diphosphorus donor ligand
P(l)-P(2) forms a four-membered ring with the
ruthenium and is selected from the group
consisting of MiniPhos and Trichickenfootphos
ligands.
16. The process as claimed in any of claims 12 to 14,
wherein the chiral diphosphorus donor ligand
P(l)-P(2) forms a five-membered ring with the
ruthenium and is selected from the group
consisting of DIPAMP, Norphos, PROPHOS, DuPHOS,
Chiraphos, Bis-P* family, DepyPhos (or DeguPhos),
RoPhos, CATAXIUM, ButiPhane, (1,2-ethylene)-
BinaPhane, (1, 2-phenylene)-BinaPhane, Binapine,
TangPhos, BPE, BasPhos, MalPhos, Me-KetalPhos,
Helmchen ligands, PennPhos, UCAP, Hoge ligands and
CNR-Phos ligands.
17. The process as claimed in any of claims 12 to 14,
wherein the chiral diphosphorus donor ligand

P(l)-P(2) forms a six-membered ring with the
ruthenium and is selected from the group
consisting of BDPP (or SKEWPHOS) BPPFOH,
MandyPhos, JosiPhos, FerroTANE Me-f-KetalPhos,
Ferrocelane, Trifer and (1,1'-ferrocene)-BinaPhane
ligands.
18.. The process as claimed in any of claims 12 to 17,
wherein LD is at least one uncharged 2-electron
donor ligand and is a solvent selected from the
group consisting of acetonitrile (CH3CN) , diethyl
ether, water, acetone, tetrahydrofuran, dioxane,
pyridine, imidazole and thiophene.
19. The process as claimed in any of claims 12 to 18,
wherein Z is a substituted open pentadienyl ligand
and is 1-methylpentadienyl, 2,4-dimethylpenta-
dienyl or 2,3,4-trimethylpentadienyl.
20. The process as claimed in any of claims 12 to 19,
wherein E- is an anion from the group consisting of
HSO4-, CF3SO3-, CF3CO2-, CH3CO2-, CIO4-, BF4-, B(aryl)4-
, SbF6- or PF6-.
21. The process as claimed in any of claims 12 to 20,
wherein dipolar, aprotic solvents such as acetone,
THF or dioxane are used as solvents.
22. A process for preparing the ruthenium complex
(type B) as claimed in any of claims 1 to 11,
wherein the cationic ruthenium complex of type A
is reacted with a negatively charged ligand Lz from
the group consisting of halides and pseudohalides.
23. The process as claimed in claim 22, wherein an
aqueous solvent mixture, in particular a mixture

of a dipolar, aprotic solvent with water, is used
as solvent
24. The use of the ruthenium complexes as claimed in
any of claims 1 to 11 as catalysts for homogeneous
asymmetric catalysis, in particular for the
homogeneous asymmetric catalytic hydrogenation of
organic compounds.
25. The use of the ruthenium complexes as claimed in
any of claims 1 to 11 as catalysts for the
enantioselective hydrogenation of C=C, C=0 or C=N
multiple bonds.

The invention relates to ruthenium complexes which have
a chiral diphosphorus donor ligand and in which the
ruthenium has the oxidation state (+11) and the chiral
diphosphorus donor ligand has bidentate P-P
coordination to the ruthenium. The ruthenium complexes
are present in two forms (cationic type A and uncharged
type B), are cyclic and have a four- to six-membered
ring incorporating the diphosphorus donor ligand. The
chiral diphosphorus donor ligands are selected from the
group consisting of diphosphines, diphospholanes,
diphosphites, diphosphonites and diazaphospholanes.
Furthermore, processes for preparing the ruthenium
complexes of types A and B, which are based on ligand
exchange reactions, are described. The Ru complexes are
used as catalysts for homogeneous asymmetric catalysis
for preparing organic compounds.

Documents:

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Patent Number

278514

Indian Patent Application Number

3646/KOLNP/2010

PG Journal Number

54/2016

Publication Date

30-Dec-2016

Grant Date

23-Dec-2016

Date of Filing

30-Sep-2010

Name of Patentee

UMICORE AG & CO. KG

Applicant Address

RODENBACHER CHAUSSEE 4 63457 HANAU-WOLFGANG GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	RIVAS-NASS, ANDREAS	EDELSTEINSTRASSE 42, 69198 SCHRIESHEIM GERMANY
2	KARCH, RALF	BAHNHOFSTRASSE 33D, 63801 KLEINOSTHEIM GERMANY
3	WINDE, ROLAND	HUEHNERWEG 18, 60599 FRANKFURT GERMANY
4	DOPPIU, ANGELINO	JAKOBSTRASSE 20, 63500 SELIGENSTADT GERMANY
5	SCHNEIDER, TINA	WASSERGASSE 15D, 63505 LANGENSELBOLD GERMANY

PCT International Classification Number

C07F 15/00

PCT International Application Number

PCT/EP2009/002204

PCT International Filing date

2009-03-26

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	08006674.9	2008-04-01	EPO
2	61/086,319	2008-08-05	EPO