Synthesis, oxidation and acid reactions of dinuclear cyclopentadienylrhodium carbonyl phosphine compounds

Article abstract of DOI:10.1016/0022-328X(89)88053-2

The dinuclear rhodium compounds (η⁵:η⁵-C10H8)2, CH2<η⁵-C5H4Rh(CO)2>2 and CH2<η⁵-C5H4Rh(CO)>2-μ-CO react with triphenylphosphine to give rhodium carbonyl phosphine derivatives.Reactions of (η⁵:η⁵-C10H8)2 with bis(diphenylphosphino)methane and either CH2<η⁵-C5H4Rh(CO)2>2 or CH2<η⁵-C5H4Rh(CO)>2-μ-CO with tetramethyldiphosphine give products in which the diphosphine ligand links the two metal atoms.CH2<η⁵-C5H4Rh(CO)<(C6H5)3P>>2 reacts with acids to form a stable, doubly protonated dication and does not give an identifiable product upon oxidation with ferrocinium hexafluorophosphate.In contrast, (η⁵:η⁵-C10H8)2-μ-<(C6H5)2P>2CH2 and CH2<η⁵-C5H4Rh(CO)>2-μ-(CH3)4P2 react both with acids and ferrocinium hexafluoroborate to give stable, diamagnetic dications which must possess Rh-Rh bonds.Reactions with acids are accompanied by dihydrogen evolution.Similarly, oxidations of (η⁵:η⁵-C10H8)2 and CH2<η⁵-C5H4Rh(CO)2>2 with ferrocinium hexafluoroborate yield diamagnetic, dicationic products.Analogous results have been previously reported for interactions of (η⁵:η⁵-C10H8)>2 with acids and with ferrocinium hexafluoroborate.