The production of class-II mixed-valence complexes in the redox reaction between dithiomalonamide and platinum(IV) or palladium(IV)

Abstract

Due to its joint reducing and complexing properties, dithiomalonamide (HL) reacts with [PtX₆]^2– and [PdX₆]^2– ions to afford two types of complexes which, on the basis of microanalytical data, may be formulated as M(HL)X₃ and M(HL)₂X₃ respectively. A detailed investigation of their behaviour in solution (¹H, ¹³C, and ¹⁹⁵Pt n.m.r.) and in the solid state (i.r., visible, x.p.s., and electrical conductivity measurements) has been performed. The experimental data show the two types of complexes to be mixed-valence compounds which are best formulated as [M^II(HL)₂][M^IVX₆] and [M^II(HL)₂][M^IV(HL)₂X₂]X₄ respectively. In these complexes, dithiomalonamide co-ordinates to palladium and platinum either via SN or S₂ donation. They are recognised as semiconductors with electrical conductivities up to –10^–4Ω^–1 cm^–1.