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 PdII and CuII ions show nearly idealized square-planar S4 co-ordination, and the ZnII 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.