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Coordination in the oxidation of cobalt(II) compounds in aqueous solutions—I

1972; Pergamon Press; Volume: 34; Issue: 11 Linguagem: Inglês

10.1016/0022-1902(72)80246-x

1878-1225

Alessandro Bondoli, V. Carunchio,

Inorganic and Organometallic Chemistry

The cobalt(III)-diethylenetriaminepentaacetic acid (DTPA) system has been investigated after oxidizing the corresponding cobalt(II) solution by hydrogen peroxide. The variation of the absorption spectra registered during oxidation shows the pH dependence of the process and suggests that the cobalt(III) compound is formed through a peroxo-bridged dinuclear species. The composition of the identified mononuclear cobalt(III)-DTPA species was determined by several spectrophotometric methods, which are in accordance in indicating the complexation ratio ML = 1:1. The formation constant of the complex was calculated by the indirect method of Hughes and Martell and the obtained value is log K = 40·5.