Study of the Reaction of Platinum(IV) with Dimethylglyoxime by UV Spectrophotometry

Abstract

The complex formation of dimethylglyoxime and platinum(IV) in alkaline medium has been investigated by ultraviolet spectroscopy. This study has shown that more than one complex species exists in solution. The effects of pH variation of ammonia buffer solution from 6.0 to 13.0 were investigated with respect to the absorption spectra. The molar ratios method, the Job's method and the method of relative recovery of complex species were used. It was found that the stoichiometric ratio Pt(IV)/dimethylglyoxime was 1:1, 1:2 and 2:1. The molar absorptivity (log ε = 4.1 at 260 nm) and the formation constant of the complex (log K2,1 = 15.0) were obtained. The stability constants of the [Pt(Hdmg)2(NH3)2] complex determined by the molar ratios and Job's method were log β2 = 9.2 ± 0.2 and log β2 = 9.3 ± 0.2, respectively.