Synthesis of [PPh4](2)[Mo(SPh)(2)(S2C2(CN)(2))(2)] (2) from [PPh4](2)[MoO(S2C2(CN)(2))(2)] (1) has been achieved to mimic the postulated {Mo(S)(6)} core of polysulfide reductase with two thiolates and two bis(ene-dithiolate) ligands. Compound 2 reacts with polysulfide to yield H2S, modeling the function of polysulfide reductase. The facile conversion of 2 back to 1 in moist solvent suggests that the interconversion of the {Mo-IV=O} and {Mo-IV-X} (X = O-Ser, S-Cys, Se-Cys) moieties might occur in the DMSO reductase class of enzymes under appropriate hydrophobic/hydrophilic conditions.