Complexes of thiazoles. Part III. Complexes of thiazole with cobalt(II), nickel(II), copper(II), zinc(II), and palladium(II) salts

Abstract

The following complexes of thiazole (t) have been prepared and characterised by magnetic and spectroscopic techniques: [M(t)₆](ClO₄)₂, where M = Co or Zn; M(t)₄X₂ where M = Co, X = Br, I, or NCS; M = Ni, X = Cl, Br, I, NCS, or ClO₄; M = Cu or Zn, X = NO₃ or ClO₄^–; M(t)₂X₂, where M = Co, X = Cl, Br, or I; M = Ni, X = Cl, Br, or NCS; M = Cu, X = Cl or Br; M = Zn, X = Cl, Br, or I; M = Pd, X = Cl; and M(t)X₂ where M = Co, X = Cl or Br and M = Cu, X = Cl. All these complexes are six co-ordinate in the solid state with bridging groups where necessary, except for Pd(t)₂Cl₂, Zn(t)₂X₂, Co(t)₂I₂ and Cu(t)Cl₂, and possibly Zn(t)₄(ClO₄)₂, but we have also been able to prepare tetrahedral Co(t)₂Br₂. We have also examined a number of equilibria in solution. The electronic spectra of the 1 :4 nickel(II) complexes (D_4h symmetry) are discussed and the complexes are compared with the analogous 1 :2 species which, apart from Ni(t)₂(NCS)₂, appear to be less distorted. The overall results are discussed in terms of the donor–acceptor properties of thiazole as a ligand.