Patent ID: 7161043

Claim:
A bidentate diphosphine composition wherein more than 60% w/w of bidentate diphosphine present has the general formula II X 1 —R—X 2 (II) wherein X 1 and X 2 independently represent an optionally substituted symmetrical phosphabicycloalkyl group, having at least 5 ring atoms; and R represents a bivalent organic bridging group, connecting both phosphorus atoms, with the proviso that the bidentate diphosphine is not 1,3-PP′bis(9phosphabicyclo[3.3.1]nonyl)propane; and wherein the remainder of the bidentate diphosphine composition is a bidentate diphosphine which has the general formula II wherein at least one of X 1 and X 2 independently represents an optionally substituted asymmetrical phosphabicycloalkyl group, having at least five ring atoms; and R represents a bivalent organic bridging group, connecting both phosphorus atoms.