| abstract |
The invention relates to a diphosphine of the following formula: R?1>P-R2-PR3R4¿ wherein R2 represents a covalent bridging group, R1 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 ('2-PA' group), and wherein R?3 and R4¿ 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. |