Mono(maleonitriledithiolene)molybdenum(IV) and Bis(μ‐sulfido)‐Bridged Dimolybdenum(V) Complexes with MoS Moiety

Abstract

Mono(maleonitriledithiolene)sulfidomolybdenum(IV) complex, [MoS(S(4))(mnt)](2-) (2; mnt=maleonitriledithiolene) was synthesized by the substitution reaction of a tetrasulfido ligand of the known [MoS(S(4))(2)](2-) (1) upon reaction with one or even excess equivalent of Na(2)(mnt) in aqueous MeCN solution in air. Surprisingly, 2 undergoes dimerization on treatment with alkyl halide such as MeI and PhCH(2)Br to form bis(μ-sulfido)dimolybdenum(V) species, [{MoS(mnt)}(2)(μ-S)(2)](2-) (3). These complexes have been characterized by IR, UV/VIS spectroscopy, cyclic voltammetry, elemental analysis, and by X-ray crystal-structure analysis. Differences in the relative stability and electrochemical behavior of 1, 2, and 3 have been correlated with theoretical calculations at DFT level.

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“…Complex 2 showed two irreversible oxidations typical for sulfur rich species. ,,, The low potential oxidation at E pa = 0.24 V is tentatively assigned for the oxidation of coordinated tetrasulfido moiety, and the oxidation at the higher potential of above 0.7 V is related to the oxidation of the dithiolene ligand; such value is common to all other dithiolene complexes. , The first irreversible reduction at E pc = −0.78 V (Figure ) may be related to the reduction of the tetrasulfido moiety in forming a radical ion. For all the complexes an irreversible reduction at around E pc = −1.85 V (Figure ) may be related to the reduction of coordinated maleonitriledithiolene ligand. , The assignments of these electrochemical data are tentative and based on the reported work of similar complexes and were not characterized spectroscopically.…”