[ReH(SH)2(PMe3)4]: A Catalyst for Fundamental Transformations Involving H2 and H2S**

While sulfur is often described as a catalyst poison, many of nature s most remarkable enzymes feature metals embedded in a sulfur-rich coordination sphere. This is especially true for the biological processing of dihydrogen, dinitrogen, and carbon monoxide.[1±3] In the industrial sector, metal sulfides are used to activate H2 in the hydrodesulfurization (HDS) process.[4, 5] Inspired by these precedents, there is much interest in metal sulfides that interact with H2. Three types of metal complexes are known to do so,[6, 7] and one, [Cp2Mo2S4] (Cpˆ cyclopentadienyl), exhibits a range of catalytic properties.[8] Encouraged by rich organic chemistry of the [ReS4]ÿion[9] and [Re2S7] we have probed the activation of dihydrogen by rhenium sulfido complexes. Initial studies revealed that the reaction of [ReS4]ÿ ions with PMe3 affords diverse compounds because PMe3 serves as both a desulfurization agent and a trapping ligand. When MeCN solutions of [NEt4][ReS4] are allowed to react with excess PMe3 under an atmosphere of H2S, we obtained a 75 % isolated yield of beige crystals of [ReH(SH)2(PMe3)4] (1). The synthesis is proposed to proceed according to Equation (1).