Platinum complexes of heteroannularly bridged heterobidentate ferrocenyl diphosphine ligands: their molecular structure and their use in catalytic carbonylation reactions

Platinum complexes PtCl2(L) and PtCl(SnCl3)(L) of the ferrocenyl diphosphine ligands (L) (R,R)-1-diphenylphosphino-2,1′-[(1-diphenylphosphino)-1,3-propanediyl]-ferrocene (1), (R,R)-1-diphenylphosphino-2,1′-[(1-dicyclohexylphosphino)-1,3-propanediyl]-ferrocene (2), (R,R)-1-bis(4-fluorophenyl)phosphino-2,1′-[(1-diphenylphosphino)-1,3-propanediyl]-ferrocene (3), have been synthesised. Complexes PtCl2(1) and PtCl2(2) have been structurally characterised by X-ray diffraction. Both the ‘preformed’ and the in situ catalysts have been used in hydroformylations of styrene. At low temperature (below 70°C) and with use of the platinum catalysts the prevailing formation of (R)-2-phenyl-propanal was observed, while at higher temperatures the formation of the (S)-enantiomer was favoured. The palladium catalysts proved to be rather inactive in the hydromethoxycarbonylation of styrene. In the presence of ligand 2 the predominant formation of the linear regioisomer was observed.