| Abstract
| - The reaction of [NH4]2MoS4 and PMe3 produces MoS2(PMe3)4, which reacts with H2S and organic thiols to produce dimetallic and tetrametallic derivatives. [Et4N]2MoS4 does not react with PMe3 but efficiently catalyzes the reaction of H2S and PMe3 to produce H2 and SPMe3.
- The reactivity of [MoS4]2- (1) toward PMe3 was explored in the presence and absence of proton donors. WhereasMeCN solutions of (Et4N)2[MoS4] and PMe3 are stable, in the presence of H2S such solutions catalyze formationof H2 and SPMe3. Addition of NH4+ to such solutions afforded MoS2(PMe3)4 (2), which can be prepared directlyfrom (NH4)2[1]. Compound 2 is reactive toward thiols via a process proposed to involve the initial dissociation ofone PMe3 ligand, a hypothesis supported by the relative inertness of trans-MoS2(dmpe)2. Benzene solutions of 2react with EtSH to give Mo2(μ-S)(μ-SH)(PMe3)4(SEt)3 (3Et). Analogous reactions with thiocresol (MeC6H4SH) andH2S gave Mo2(μ-S)(μ-SH)(PMe3)4(SR)3 (R = tol, H). Crystallographic analyses of 3Et, 3H, and 3tol indicate dinuclearspecies with seven terminal ligands and a Mo2(μ-SR)(μ-S) core (rMo-Mo = 2.748(1) Å). From reaction mixturesleading to 3Et from 2, we obtained the intermediate MoIV2(μ-S)2(SEt)4(PMe3)2 (4), an edge-shared bis(trigonalpyramidal) structure. Compounds 3H and 3Et react further with H2S to give Mo4(μ2-S)4(μ3-S)2(PMe3)6(SH)2 (5H)and Mo4(μ2-S)4(μ3-S)2(PMe3)6(SEt)2 (5Et), respectively. Analogously, W4(μ2-S)4(μ3-S)2(PMe3)6(SH)2 was synthesized from a methanol solution of (NH4)2WS4 with H2S and PMe3. A highly accurate crystallographic analysis of(NH4)2MoS4 (R1 = 0.0193) indicates several weak NH···S interactions.
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