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 Pt ^III dinuclear complexes with phenol proceeded only at pH > 3, whereas that of the HT Pt ^III dinuclear complex with phenol proceeded even at a pH as low as zero. The kinetic evaluations revealed that the Pt ^III 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.