The catalytic effect of [PtII2(NH3)4(C4H6NO)2]2+ (PtII2 dimer; C4H6NO = α-pyrrolidonate) in the O2 oxidation of hydroquinone to quinone is investigated at pH 5. Both the O2 oxidation of this dimer into [PtIII2(NH3)4(C4H6NO)2(L)2]4+ (PtIII2 dimer; L = OH2, OH-, SO42-, etc.) and the re-reduction of the PtIII2 dimer into the PtII2 dimer by hydroquinone were found to be thermodynamically favorable. With an excess of hydroquinone, the rate of the catalytic reaction exceeds that of the former reaction and is roughly linear to the hydroquinone concentration, suggesting that a certain intermediate formed in the reaction between the PtII2 dimer and O2 plays a major role in the present catalysis. In addition, hydrolysis equilibria for the axial aqua ligands on the PtIII2 dimer are investigated spectrophotometrically.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry