Syntheses and Structure of Ni(III) Complexes with 1-Toulene-3,4-dithiole. Bond-Valence Approach to the Oxidation State of the Central Atom

The complex compounds of the formula (R)[NiIII(tdt)2], R = Met4N (I), Et4N (II), Pr4N (III), MePh3P (IV), Ph4P (V); tdt = 1-toluene-3,4-dithiole have been synthesized. The crystal structures of the compounds III and IVwere determined by X-rays studies. Bond valence as a function of inter-nuclear distance for Ni-S bonds was estimated. On the basis of physico-chemical measurements and bond-valence sum model, the formal oxidation state III of Ni atoms for both structures was proposed.