Diphosphines

Abstract

The invention relates to a diphosphine of the following formula R.sup.1 >P-R.sup.2 -PR.sup.3 R.sup.4 wherein R.sup.2 represents a covalent bridging group, R.sup.1 represents a bivalent radical that together with the phosphorus atom to which it is attached is an optionally substituted 2-phospha-tricyclo[3.3.1.1{3,7}]decyl group or a derivative thereof in which one or more of the carbon atoms are replaced by heteroatoms ("6-PA" group), and wherein R.sup.3 and R.sup.4 independently represent univalent radicals of up to 20 atoms or jointly form a bivalent radical of up to 20 atoms; to carbonylation catalysts obtainable by combining: (i) a metal cation selected from the groups 8, 9 or 10 of the Periodic Table of Elements, and (ii) the new diphosphine; and furthermore to a process for carbonylating unsaturated compounds in the presence of the carbonylation catalyst.

Dependencies are inferred from the claim text.