Syntheses and molecular structure of bis(1-substituted, 2.4-dithiobiuretato)- nickel(II) complexes

Abstract

Bis(1-substituted, 2.4-dithiobiuretato)nickel(II) complexes, where 1-substituted groups = C₂H₅, n-C₃H₇, iso-C₃H₇, o-tolyl and p-anisidine, have been prepared and characterized on the basis of elemental analyses, magnetic moments at room temperature and electronic spectra. The crystal structure of bis(1-isopropyl-2,4-dithiobiuretato)nickel(II)·2(dimethylformamide) has been determined from 1446 X-ray diffraction data. The crystals are monoclinic, space group P2₁/c, with two formula units in a unit cell of dimensions a = 8.008(2), b = 14.460(5), c = 12.059(5) Å and β = 106.45(3)°. The structure was solved by conventional Patterson and Fourier methods, and block-diagonal least-squares refinements led to a final discrepancy index 0.038. The structure consists of discrete bis(1-isopropyl-2,4-dithiobuiretato)nickel(II) and dimethylformamide molecules, and the former molecule is centrosymmetric with the two bidentate ligands of isopropyl- 2,4-ditiobuiretato chelating to the central nickel atom through the two sulfur atoms. Examination of the bond distances and the planarity of the molecule revealed that the π-conjugation system extends over the 2,4-dithiobiuretato moiety.