Platinum complexes having ferrocene diphosphine ligands for catalysis of the hydroxycarbonylation of ethylenically unsaturated compounds

A process comprising:

• a) adding an ethylenically unsaturated compound to form a reaction mixture;
• b) adding to the reaction mixture a platinum complex having a ferrocene-diphosphine ligand of formula (I)
• where
• R1, R2, R, and R4 are each independently selected from —(C1-C12)-alkyl, —(C6-C20)— or heteroaryl or
• adding to the reaction mixture the ligand of formula (I) and a Pt compound;
• c) adding to the reaction mixture an acid;
• d) feeding into the reaction mixture CO;
• e) heating the reaction mixture formed from a) to d), to convert the ethylenically unsaturated compound to a carboxylic acid.