Dithio-oxamides as ligands: crystal structures and vibrational analyses of bis(N,N′-dicyclohexyldithio-oxamidato)palladium(II), bis(N,N′-dibenzyldithio-oxamide) copper(II) diperchlorate, and dichloro(N,N′-dimethyldithio-oxamide) zinc(II) and the carbon-13 nuclear magnetic resonance spectra of related compounds

Abstract

Three N,N′-disubstituted dithio-oxamide metal complexes [Pd(Hdcdto)₂], [Cu(H₂dbzdto)₂][ClO₄]₂, and [Zn(H₂dmdto)Cl₂](H₂dcdto, H₂dbzdto, and H₂dmdto =N,N′-dicyclohexyl-, N,N′-dibenzyl-, and N,N′-dimethyl-dithio-oxamide respectively) have been prepared and their crystal and molecular structures determined for the first time. In all cases the N,N′-disubstituted dithio-oxamides act as S,S′-chelating ligands. The Pd^II and Cu^II ions show nearly idealized square-planar S₄ co-ordination, and the Zn^II ion a distorted tetrahedral S₂Cl₂ co-ordination geometry. The co-ordination ability of the organic ligands and the conformations of their chelate rings are discussed. The i.r. spectra of the complexes are discussed and compared with analogous compounds. The ¹³C n.m.r. spectra of related complexes have been recorded in the solid state and in solution. E.s.r. spectra of a series of copper(II) complexes are also discussed in the light of the covalent strength of the ligands.