Polynuclear complex formation and peroxodisulphate oxidation of copper(II)–dimethylglyoximate complexes
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 8,p. 744-751
- https://doi.org/10.1039/dt9770000744
Abstract
The interaction of copper(II) with dimethylglyoxime (H2dmg) has been studied potentiometrically in the range pH 2.5–11.0. For H2dmg : CuII= 2 : 1, only [Cu(Hdmg)2] is present in solution; no [Cu(Hdmg)]+ has been detected. At H2dmg : CuII= 1 : 1, the predominant species at pH 5 is still [Cu(Hdmg)2], but at higher pH (5–6.5) there is evidence that the predominant species is a tetramer. This complex. and its glyoxime analogue. can be isolated and spectroscopic data and elemental analysis indicatean empirical formula [{Cu(Hdmg)(OH)}4], for which a hydroxo-bridged structure retaining two [CuN4] units is suggested. The same structure is retained in solution. The kinetics of oxidation of alkaline solutions of H2dmg : CuII= 1 : 1 have been studied. The reactions proceed by interaction of the tetramer with peroxodisulphate to give two molecules of a dimer having mixed oxidation states for the metal. It is suggested that oxidation occurs preferentially at the hydroxo-bridges of the tetramer.Keywords
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