Transition metal complexes of dithioacetylacetone and diselenoacetylacetone: syntheses, properties, and infrared spectra

Abstract

The synthesis and properties of some cobalt(II) and nickel(II) complexes of dithioacetylacetone and diselenoacetylacetone are described. Unlike the corresponding acetylacetonates, the cobalt and nickel complexes are square-coordinated monomers with ground states of spin S = 1/2 and S = 0, respectively. For divalent nickel, the isolation of a mixed complex containing one monothioacetylacetonate and one dithioacetylacetonate bidentate ligand completes the NiS₂O₂, NiS₃O, NiS₄ series of diamagnetic monomers.   A tentative mechanism is proposed for the course of the reaction which leads to these compounds under the experimental conditions first formulated by Martin and Stewart. The infrared absorption spectra have been assigned on the basis of a normal coordinate analysis taken in conjunction with the unusually favourable circumstances offered by a closely related series of square-coordinated monomers [Cu(acac)₂], [Co(SacSac)₂], [Ni(SeacSeac)₂].