Redox Reactions of Amidato-Bridged cis-Diammineplatinum(III) Dinuclear Complexes with Phenol

Kinetic studies of the redox reactions of the head-to-tail (HT) α-pyridonato-bridged cis-diammineplatinum(III) dinuclear complex and of the head-to-head (HH) α-pyridonato-bridged and α-pyrrolidonato-bridged cis-diammineplatinum(III) dinuclear complexes with phenol were performed in acidic aqueous solution. Reduction of the HH PtIII dinuclear complexes with phenol proceeded only at pH > 3, whereas that of the HT PtIII dinuclear complex with phenol proceeded even at a pH as low as zero. The kinetic evaluations revealed that the PtIII dinuclear complexes are not reduced by the phenol molecule but are reduced by the phenoxide ion, and the reduction reaction proceeds through an outer-sphere electron-transfer mechanism.