Catalyst comprising a complex of a metal from subgroup VIII based on a bidentate phosphonite ligand, and method for producing nitriles

A catalyst composition comprising a complex of a metal of group VIII, and a bidentate phosphonite ligand of the formula I

• where
• A is a C2- to C7-alkylene bridge which may have 1, 2 or 3 double bonds and/or 1, 2 or 3 substituents which are selected from alkyl, cycloalkyl and aryl, it being possible for the aryl substituent additionally to carry 1, 2 or 3 substituents which are selected from alkyl, alkoxy, halogen, trifluoromethyl, nitro, alkoxycarbonyl and cyano, and/or the C2- to C7-alkylene bridge may be interrupted by 1, 2 or 3 non-neighboring, unsubstituted or substituted heteroatoms, and/or the C2- to C7-alkylene bridge may be fused with one, two or three aryl and/or hetaryl groups, it being possible for the fused aryl and hetaryl groups each to carry 1, 2 or 3 substituents which are selected from alkyl, cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy, acyl, halogen, trifluoromethyl, nitro, cyano, carboxyl, alkoxycarbonyl and NE1E2, where E1 and E2 are identical or different and are each alkyl, cycloalkyl or aryl,
• R1 and R1′, independently of one another, are each alkyl, cycloalkyl, aryl or hetaryl, each of which may carry 1, 2 or 3 substituents which are selected from alkyl, cycloalkyl and aryl,
• R2 and R2′, independently of one another, are each alkyl, cycloalkyl, aryl or hetaryl, it being possible for the aryl and hetaryl groups each to carry 1, 2 or 3 substituents which are selected from alkyl, cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy, acyl, halogen trifluoromethyl, nitro, cyano, carboxyl, alkoxycarbonyl and NE1E2, where E1 and E2 may have the abovementioned meanings, or a salt or mixture thereof.