A New Entry into Molybdenum/Tungsten Sulfur Chemistry: Synthesis and Reactions of Mononuclear Sulfido Complexes of Pentamethylcyclopentadienyl−Molybdenum(VI) and −Tungsten(VI)

Abstract

A series of mononuclear thio complexes of pentamethylcyclopentadienyl−molybdenum(VI) and −tungsten(VI) have been synthesized via C−S bond-cleaving reactions of thiolates. Use of Li2S2 for sulfurization of Cp*MoCl4 resulted in the known dinuclear complex, anti-Cp*2Mo2(S)2(μ-S)2 (1), while the analogous reaction of Cp*WCl4 gave rise to anti-Cp*2W2(S)2(μ-S)2 (2) and (PPh4)[Cp*W(S)3] (3), the latter of which was isolated after the subsequent cation exchange reaction with PPh4Br. In contrast, the reaction of Cp*WCl4 with Li2edt (edt = SCH2CH2S) followed by treatment with PPh4Br generated 3 as the sole isolable product in high yield. A similar reaction between Cp*WCl4 and LiStBu afforded Cp*W(S)2(StBu) (6), which turned out to be thermally unstable in solution and gradually degraded to 2. In these reactions of Cp*WCl4 with lithium thiolates, a facile C−S bond cleavage took place and the tungsten atom was oxidized from W(V) to W(VI). On the other hand, the Mo(IV) thiolate complexes, Cp*Mo(StBu)3 (4) and (PPh4)[C...