[Mo₂O₂S₂]-Based Oxothiomolybdates and Their Reactivity with Pyrazole and Triazole

Extending the family of oxothiomolybdates, the interaction of the cyclic anion [Mo₈O₈S₈(OH)₈(C₂O₄)]²⁻ and the complex [Mo₄O₄S₄(C₂O₄)₅]⁶⁻ with organic compounds of the azole series—pyrazole (pzH) and 1,2,4-triazole (trzH) in water solution and in the melt of ligands was investigated. In water solution pyrazole plays only the role of cation (upon protonation) to form the complex (pzH₂)₂[Mo₂O₂S₂(C₂O₄)₂(H₂O)₂]. While in the reaction in melt of pzH in the case of the initial cyclic anion, the resulting anionic product [Mo₆O₆S₆(pz)₆(MoO₄)]²⁻ represents a pioneering example of a cyclic oxothiometalate {Mo₆} anchored by the coordination of six bridging pyrazolates (pz), complemented by a MoO₄²⁻ core. At the same time, the interaction of [Mo₄O₄S₄(C₂O₄)₅]⁶⁻ with pzH and trzH melts yields the binuclear clusters [Mo₂O₂S₂(C₂O₄)₂L₂]²⁻, where L = pzH or trzH. The composition and structures of the compounds were determined using a variety of physicochemical methods, including single-crystal X-ray diffraction analysis.