# US 10,500,578 B2 · Catalyst compositions and their use for hydrogenation of nitrile rubber

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- Number: US 10,500,578 B2
- Document ID: US10500578B2
- Status: Granted
- Kind: B2
- Application number: 15/867,347
- Filed: 2018-01-10
- Published: 2018-10-18
- Granted: 2019-12-10
- Earliest claimed: 2011-10-21
- Assignees: Arlanxeo Deutschland GmbH
- Applicants: Lanxess Deutschland GmbH
- Inventors: Werner Obrecht; Sarah David; Qingchun Liu; Zhenli Wei
- Web page: https://patentgrep.com/patent/US10500578B2

## CPC

- B01J 31/2208: {Oxygen, e.g. acetylacetonates}
- B01J 31/0204: {Ethers}
- B01J 31/1805: {the ligands containing nitrogen}
- B01J 31/2273: {with only nitrogen as heteroatomic ring members, e.g. 1,3-diarylimidazoline-2-ylidenes}
- B01J 31/2278: {Complexes comprising two carbene ligands differing from each other, e.g. Grubbs second generation catalysts}
- B01J 31/2295: {Cyclic compounds, e.g. cyclopentadienyls}
- B01J 31/2404: {Cyclic ligands, including e.g. non-condensed polycyclic ligands, the phosphine-P atom being a ring member or a substituent on the ring}
- C08C 19/02: Hydrogenation
- B01J 2231/543: alkene metathesis
- B01J 2231/641: Hydrogenation of organic substrates, i.e. H2 or H-transfer hydrogenations, e.g. Fischer-Tropsch processes
- B01J 2231/645: of C=C or C-C triple bonds
- B01J 2531/821: Ruthenium
- B01J 2531/825: Osmium
- B01J 2540/22: comprising fluorine, e.g. trifluoroacetate
- B01J 2540/34: Sulfonyl groups
- B01J 2540/62: Activating groups
- C08C 19/00: Chemical modification of rubber
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C08C: TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS

## Abstract

This invention relates to novel catalyst compositions based on Ruthenium- or Osmium-based complex catalysts of the Grubbs-Hoveyda, Grela or Zhan type and specific co-catalysts comprising at least one vinyl group, pref. ethyl vinyl ether, and to a process for selectively hydrogenating nitrile rubbers in the presence of such catalyst compositions, preferably with a preceding metathesis step using the same complex catalyst as in the hydrogenation step.

## Claims

### Claim 1

A selective hydrogenation of nitrile rubber comprising selectively hydrogenating nitrile rubber in the presence of a catalyst composition obtained by contacting a complex catalyst with at least one co-catalyst in a molar ratio of the complex catalyst to the co-catalyst of 1:30 to 1:100, wherein:
the complex catalyst has the general formula (A)
where
M is ruthenium or osmium,
X1 and X2 are identical or different ligands,
L is an electron donating ligand, which can be linked or not linked with X1 to form a cyclic structure,
R1 is hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl,
R2, R3, R4 and R5 are identical or different and are each hydrogen or an organic or inorganic substituent,
R6 is H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R, —S(═O)R, or a group containing either a C═O or a C═S structural element adjacent to a carbon atom which is bound to Y,
n is 0 or 1,
wherein if n=1, then the element shall mean that Y and (E)n are linked either by a single bond or by a double bond, wherein
(i) if Y and (E)n are linked by a single bond, then
Y is oxygen (O), sulfur (S), N—R or P—R, and
E is CH2, or
(ii) if Y and (E)n are linked by a double bond, then
Y is N or P, and
E is CH, and
wherein if n=0, then
Y is oxygen (O), sulfur (S), N—R or P—R, and is directly linked by a single bond to the phenyl moiety depicted above in formula (A), and
wherein in all above occurrences of general formula (A), R is hydrogen or alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl; and
wherein the co-catalyst must contain at least one vinyl group, and has the general formula (1)
CH2═CRR′ (1)
in which R and R′ are identical or different and in the co-catalyst shall mean hydrogen, wherein R and R′ must not both represent hydrogen, or
OR1 wherein R1 shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl, C(═O)(R2), —C(═O)N(R2)2, —[(CH2)n—X]mR2, —[(CH2)n—X]m—CH═CH2, or —(CH2)p—C(R3)2R4, wherein
X is identical or different and means oxygen (O) or NR2
R2 are identical or different and represent H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl,
R3 are identical or different and represent C1-C8 alkyl or —(CH2)n′—O—CH═CH2,
R4 represents (CH2)p′—O—CH═CH2,
n is 1 to 5,
m is 1 to 10,
p is 0 to 5, or
where in the alternative, if R and R′ both represent a group OR1, both R1 may be linked to each other and together represent a divalent group —(C(R2)2)q—with q being 2, 3 or 4 and R2 being identical or different and having the above defined meanings, or
SR5, SOR5, SO2R5 wherein R5 represents alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl, or
N(R6R7), P(R6R7) wherein R6 and R7 are identical or different and shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, —C(═O)(R2), or where in the alternative R6 and R7 may form together with such N or P atom to which they both are linked at the same time a saturated, unsaturated or aromatic cyclic structure with 4 to 7 carbon atoms in the cyclic structure wherein one, two or three of said carbon atoms can be replaced by a moiety selected from oxygen, sulfur, nitrogen, N—R8 or P—R8 wherein R8 shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl; or
P(═O)(OR9)2 in which R9 are identical or different and shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl.

### Claim 2 (depends on 1)

The selective hydrogenation according to claim 1, wherein the complex catalyst is contacted with one co-catalyst of the general formula (1) in which R is hydrogen and R′ shall mean,
OR1 wherein R1 shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, C6-C24-heteroaryl, —C(═O)(R2)2, —C(═O)N(R2)2, —[(CH2)nX]mR2, —[(CH2)nX]m—CH═CH2, or —(CH2)p—C(R3)2R41,
wherein
X is identical or different and is oxygen (O) or NR2,
R2 are identical or different and represent H, C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C3-C20-heteroaryl,
R3 are identical or different and represent C1-C4 alkyl or —(CH2)n—O—CH═CH2,
R4 represents (CH2)p—O—CH═CH2,
n is 1 to 4,
m is 1 to 5,
p is 0 to 5, or
SR5, SOR5, SO2R5 wherein R5 represents C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, or
N(R6R7), P(R6R7) wherein R6 and R7 are identical or different and shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, —C(═O)(R2), or where in the alternative R6 and R7 may form together with such N or P atom to which they both are linked at the same time a saturated, unsaturated or aromatic cyclic structure with 4 to 7 carbon atoms in the cyclic structure wherein one, two or three of said carbon atoms can be replaced by a moiety selected from oxygen, sulfur, nitrogen, N—R8 or P—R8 wherein R8 shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, or
P(═O)(OR9)2 in which R9 are identical or different and shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl.

### Claim 3 (depends on 1)

The selective hydrogenation according to claim 1, wherein the complex catalyst is contacted with one co-catalyst of the general formula (1) in which R and R′ are identical or different and shall mean
OR1 wherein R1 shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, C6-C24-heteroaryl, —C(═O)(R2), —C(═O)N(R2)2, —[(CH2)nX]mR2, —[(CH2)nX]m—CH═CH2, or —(CH2)p—C(R3)2R4,
wherein
X is identical or different and oxygen (O) or NR2,
R2 are identical or different and represent H, C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C3-C20-heteroaryl,
R3 are identical or different and represent C1-C4 alkyl or —(CH2)n—O—CH═CH2,
R4 represents (CH2)p—O—CH═CH2,
n is 1 to 4,
m is 1 to 5,
p is 0 to 5,
where in the alternative, if R and R′ both represent a group OR1, both R1 may be linked to each other and together represent a divalent group —(C(R2)2)q—with q being 2, 3 or 4, and R2 being identical or different and having the above defined meanings, or
SR5, SOR5, SO2R5 wherein R5 represents C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, or
N(R6R7), P(R6R7) wherein R6 and R7 are identical or different and shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, —C(═O)(R2), or where in the alternative R6 and R7 may form together with such N or P atom to which they both are linked at the same time a saturated, unsaturated or aromatic cyclic structure with 4 to 7 carbon atoms in the cyclic structure wherein one, two or three of said carbon atoms can be replaced by a moiety selected from oxygen, sulfur, nitrogen, N—R8 or P—R8 wherein R8 shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl, or
P(═O)(OR9)2 in which R9 are identical or different and shall mean C1-C16-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C6-C24-heteroaryl.

### Claim 4 (depends on 1)

The selective hydrogenation according to claim 1, wherein the complex catalyst is contacted with one co-catalyst of the general formula (1) in which R is hydrogen and R′ represents
OR1 wherein R1 shall mean C1-C6-alkyl, C5-C6-cycloalkyl, C2-C6-alkenyl, C2-C6-alkynyl, phenyl, imidazolyl, triazolyl, or pyridinyl, —C(═O)(R2), —C(═O)N(R2)2, —[(CH2)nO]mR2, —[(CH2)nO]m—CH═CH2, or —(CH2)p—C(R3)2R4,
wherein
R2 are identical or different and represent H, C1-C6-alkyl, C5-C8-cycloalkyl, C2-C8-alkenyl, C2-C8-alkynyl, phenyl, imidazolyl, triazolyl, or pyridinyl,
R3 are identical or different and represent methyl, ethyl or —(CH2)n—O—CH═CH2,
R4 represents (CH2)p—O—CH═CH2,
n is 1, or 2,
m is 1, 2, or 3, and
p is 0, 1, or 3.

### Claim 5 (depends on 1)

The selective hydrogenation according to claim 1, wherein the co-catalyst is selected from the group consisting of formulae (cocat-1) to (cocat-31) and (cocat-33) to (cocat-38):

### Claim 6 (depends on 1)

The selective hydrogenation according to claim 1, wherein the complex catalyst is selected from the group consisting of:
(i) catalysts of general formula (A1),
wherein M, L, X1, X2, R2, R3, R4, R5, R6, n and E can have the meanings mentioned for the general formula (A) in claim 1,
(iii) catalysts of general formula (A3)
where
X1 and X2 are identical or different and shall mean hydrogen, halogen, pseudohalogen, straight-chain or branched C1-C30-alkyl, C6-C24-aryl, C1-C20-alkoxy, C6-C24-aryloxy, C3-C20-alkyldiketonate C6-C24-aryldiketonate, C1-C20-carboxylate, C1-C20-alkylsulfonate, C6-C24-arylsulfonate, C1-20-alkylthiol, C6-C24-arylthiol, C1-20-alkylsulfonyl or C1-C20-alkylsulfinyl,
L is an electron donating ligand, which can be linked or not linked with X1 to form a cyclic structure,
R3 is chloro, fluoro, bromo, —C(═O)R, —C(═O)OR, —OC(═O)R, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R, or —S(═O)R,
R4 is H, halogen, nitro, cyano, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, —Si(R)3, —O—Si(R)3, C6-C20 aryl, C6-C20 aryloxy, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R or —S(═O)R,
R2 and R5 are each H, bromo (Br), iodo (I), C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, —Si(R)3, —O—Si(R)3, C6-C20 aryloxy, C6-C20 aryl, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)OR, —C(═O)N(R)2, or —SO2N(R)2,
R6 is H, C1-C20 alkyl, C6-C20 aryl, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —SO2N(R)2, or —N(SO2—R)2, —S(═O)R, or —S(═O)2R, and
n is 0 or 1,
wherein if n=1, then the element
shall mean that Y and (E)r, are linked either by a single bond or by a double bond, wherein
(i) if Y and (E)r, are linked by a single bond, then
Y is oxygen (O), sulfur (S), N—R or P—R and
E is CH2,or
(ii) if Y and (E), are linked by a double bond, then
Y is N or P
E is CH,
wherein if n=0, then
Y is oxygen (O), sulfur (S), N—R or P—R and directly linked by a single bond to the phenyl moiety depicted above in formula (A3), and
wherein in all above occurrences in formula (A3) R is identical or different and shall mean H, C1-C20-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C2-C24-heteroaryl, or if two substituents R are bound to the same atom, such two substituents R may also form a saturated or unsaturated cyclic structure together with the atoms to which they are bound,
(iv) catalysts of general formula (A4)
wherein M, L, Y, X1, X2, R1, R2, R3, R4, R5, R6 and n have the meanings given for general formula (A), and
(vii) catalysts of general formula (A7)
where
X1 and X2 are identical or different and shall mean hydrogen, halogen, pseudohalogen, straight-chain or branched C1-C30-alkyl, C6-C24-aryl, C1-C20-alkoxy, C6-C24-aryloxy, C3-C20-alkyldiketonate C6-C24-aryldiketonate, C1-C20-carboxylate, C1-C20-alkylsulfonate, C6-C24-arylsulfonate, C1-C20-alkylthiol, C6-C24-arylthiol, C1-20-alkylsulfonyl or C1-C20-alkylsulfinyl,
L is an electron donating ligand, which can be linked or not linked with X1 to form a cyclic structure,
Y is NR or PR, preferably NR,
R3 is chloro, fluoro, bromo, —C(═O)R, —C(═O)OR, —OC(═O)R, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R, or —S(═O)R,
R4 is H, halogen, nitro, cyano, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, —Si(R)3, —O—Si(R)3, C6-C20 aryl, C6-C20 aryloxy, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R or —S(═O)R,
R2 and R5 are each H, bromo (Br), iodo (I), C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, —Si(R)3, —O—Si(R)3, C6-C20 aryloxy, C6-C20 aryl, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)OR, —C(═O)N(R)2, or —SO2N(R)2 ,
R6 is H, C1-C20 alkyl, C6-C20 aryl, C2-C20 heterocyclic, C2-C20 heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —SO2N(R)2, —N(SO2—R)2, —S(═O)R, or —S(═O)2R, and
wherein in all above occurrences in formula (A7) R is identical or different and shall mean H, C1-C20-alkyl, C3-C10-cycloalkyl, C2-C16-alkenyl, C2-C20-alkynyl, C6-C24-aryl, or C2-C24-heteroaryl, or if two substituents R are bound to the same atom, such two substituents R may also form a saturated or unsaturated cyclic structure together with the atoms to which they are bound.

### Claim 7 (depends on 1)

The selective hydrogenation according to claim 1, wherein the complex catalyst is selected from the group consisting of the below shown formulae, wherein Mes is in each case 2,4,6-trimethylphenyl, Ph is phenyl,

### Claim 8 (depends on 1)

The selective hydrogenation according to claim 1, further comprising:
a) preparing the catalyst composition according to claim 1 by contacting the complex catalyst according to claim 1 with the at least one co-catalyst according to claim 1 in a molar ratio of the complex catalyst to the co-catalyst of 1:30 to 1:100, and thereafter
b) hydrogenating nitrile rubber in the presence of the catalyst composition formed in step a).

### Claim 9 (depends on 8)

The selective hydrogenation according to claim 8, wherein step a) is performed at a temperature of −20° C. to 160° C.

### Claim 10 (depends on 9)

The selective hydrogenation according to claim 9, wherein the hydrogenation in step b) is carried out at a temperature of 60° C. to 200° C., and at a hydrogen pressure of 0.5 MPa to 35 MPa.

### Claim 11 (depends on 1, 8)

The selective hydrogenation according to claim 8, wherein the nitrile rubber is subjected to a molecular weight degradation in a metathesis reaction first comprising contacting the nitrile rubber in the absence or presence of a co-olefin with the complex catalyst according to claim 1, then
a) contacting the complex catalyst which is present in the reaction mixture obtained after the metathesis reaction with at least one co-catalyst having at least one vinyl group in a molar ratio of the complex catalyst to the co-catalyst of 1:30 to 1:100, to form a catalyst composition, and thereafter
b) hydrogenating the nitrile rubber in the presence of the catalyst composition.

### Claim 12 (depends on 1)

The selective hydrogenation according to claim 1, wherein the catalyst has the general formula (A2)
wherein M, L, X1, X2, R1, R2, R4, R5, R6, n and E have the meanings mentioned for the formula (A) in claim 1.

### Claim 13 (depends on 1)

The selective hydrogenation according to claim 1, wherein the catalyst is selected from the group consisting of
catalysts of general formula (A6)
where
M is ruthenium or osmium,
Z is oxygen (O) or sulfur (S),
Y is oxygen (O), sulfur (S), N—R7 or P—R7, where R7 is alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl which may each be optionally substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents,
X1 and X2 are identical or different ligands,
R1 is H, alkyl, alkenyl, alkynyl or aryl,
R2, R3, R4 and R5 are identical or different and are each hydrogen, organic or inorganic substituents,
R61 is H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl, each of which may optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents,
R62 is alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl, each of which may optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents, or, in the alternative R61 and R62 form a cyclic structure together with the two adjacent carbon atoms to which they are bound,
L is a ligand, and
n is 0 or 1.

### Claim 14

A selective hydrogenation of nitrile rubber in the presence of a catalyst composition obtained by contacting a complex catalyst with at least one co-catalyst in a molar ratio of the complex catalyst to the co-catalyst of 1:30 to 1:100, wherein:
the complex catalyst has the general formula (A5)
where
Y is oxygen (O) or —NR, with R representing hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl,
W is oxygen (O) or NR7, with R7 being hydrogen or straight chain or branched C1-C10 alkyl,
R15 represents straight chain or branched alkyl,
R16, R17, R18 and R19 are identical or different and represent hydrogen, halogen, alkyl, cycloalkyl, alkoxy, alkenyl, alkynyl, aryl or heteroaryl,
M is ruthenium or osmium,
X1 and X2 are identical or different ligands,
L is an electron donating ligand, which can be linked or not linked with X1 to form a cyclic structure,
R1 is hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl,
R2, R3, R4 and R5 are identical or different and are each hydrogen or an organic or inorganic substituent; and
wherein the co-catalyst must contain at least one vinyl group and has the general formula (1)
CH2═CRR′ (1)
in which R and R′ are identical or different and in the co-catalyst shall mean hydrogen, wherein R and R′ must not both represent hydrogen, or
OR1 wherein R1 shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl, C(═O)(R2), —C(═O)N(R2)2, —[(CH2)m—X]mR2, —[(CH2)n—X]m—CH═CH2, or —(CH2)p—C(R3)2R4, wherein
X is identical or different and means oxygen (O) or NR2
R2 are identical or different and represent H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl,
R3 are identical or different and represent C1-C8 alkyl or —(CH2)n′—O—CH═CH2,
R4 represents (CH2)p—O—CH═CH2,
n is 1 to 5,
m is 1 to 10,
p is 0 to 5, or
where in the alternative, if R and R′ both represent a group OR1, both R1 may be linked to each other and together represent a divalent group —(C(R2)2)q—with q being 2, 3 or 4 and R2 being identical or different and having the above defined meanings, or
SR5, SOR5, SO2R5 wherein R5 represents alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl, or
N(R6R7), P(R6R7) wherein R6 and R7 are identical or different and shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, —C(═O)(R2), or where in the alternative R6 and R7 may form together with such N or P atom to which they both are linked at the same time a saturated, unsaturated or aromatic cyclic structure with 4 to 7 carbon atoms in the cyclic structure wherein one, two or three of said carbon atoms can be replaced by a moiety selected from oxygen, sulfur, nitrogen, N—R8 or P—R8 wherein R8 shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl; or
P(═O)(OR9)2 in which R9 are identical or different and shall mean alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl.

### Claim 15 (depends on 14)

The selective hydrogenation according to claim 14, wherein the complex catalyst is selected from the group consisting of the below shown formulae, wherein Mes is in each case 2,4,6-trimethylphenyl, Ph is phenyl,

### Claim 16

A selective hydrogenation of nitrile rubber in the presence of a catalyst composition obtained by contacting a complex catalyst with at least one co-catalyst in a molar ratio of the complex catalyst to the co-catalyst of 1:30 to 1:100, wherein:
the complex catalyst has the general formula (A)
where
M is ruthenium or osmium,
X1 and X2 are identical or different ligands,
L is an electron donating ligand, which can be linked or not linked with X1 to form a cyclic structure,
R1 is hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl,
R2, R3, R4 and R5 are identical or different and are each hydrogen or an organic or inorganic substituent,
R6 is H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, —C(═O)R, —C(═O)OR, —C(═O)N(R)2, —C(═S)R, —C(═S)SR, —C(═S)OR, —C(═S)N(R)2, —S(═O)2N(R)2, —S(═O)2R, —S(═O)R, or a group containing either a C═O or a C═S structural element adjacent to a carbon atom which is bound to Y,
n is 0 or 1,
wherein if n=1, then the element
shall mean that Y and (E)n, are linked either by a single bond or by a double bond, wherein
(i) if Y and (E)n are linked by a single bond, then
Y is oxygen (O), sulfur (S), N—R or P—R, and
E is CH2, or
(ii) if Y and (E)n are linked by a double bond, then
Y is N or P, and
E is CH and
wherein if n=0, then
Y is oxygen (O), sulfur (S), N—R or P—R, and is directly linked by a single bond to the phenyl moiety depicted above in formula (A), and
wherein in all above occurrences of general formula (A), R is hydrogen or alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl; and
wherein the co-catalyst is of formula (cocat-32)