Polarography of coordinated oximes

Abstract

The polarographic reduction of dimethylglyoxime, cyclohexane-1,2-dione dioxime (nioxime), α-furil dioxime, and salicylaldoxime chelated to cobalt(II) and iron(II) has been investigated. Unlike the parent ligand, the reduction of the coordinated ligand proceeds in two equal steps in acid solutions. The intermediate half-way stage is suggested to be the hydroxylamine of the oxime. Results of the controlled potential electrolysis of the cobalt(II)-dimethylglyoxime chelate also supports this view. In alkaline solution reduction stops at the half- way stage since the product of half-way reduction, presumably the corresponding hydroxylamine, is not further reduced in the available potential range. The first step of reduction occurs invariably at a potential less negative than that of the parent ligand.