Reactions of Heterometallic Phosphinidene-Bridged MoMn and MoRe Complexes with Sulfur and Selenium: From Chalcogenophosphinidene- to Trithiophosphonate-Bridged Derivatives

[Image: see text] Reactions of [MoReCp(μ-PR*)(CO)(6)] with S(8) were strongly dependent on experimental conditions (R* = 2,4,6-C(6)H(2)(t)Bu(3)). When using 1 equiv of sulfur, complex [MoReCp(μ-η(2):κ(1)(S)-SPR*)(CO)(6)] was slowly formed at 313 K, with a thiophosphinidene ligand unexpectedly bridging the dimetal center in the novel μ-κ(1)(S):η(2) coordination mode, as opposed to the μ-κ(1)(P):η(2) mode usually found in related complexes. The latter underwent fast decarbonylation at 363 K to give [MoReCp(μ-η(2):η(2)-SPR*)(CO)(5)], with a six-electron donor thiophosphinidene ligand rearranged into the rare μ-η(2):η(2) coordination mode. Depending on reaction conditions, reactions with excess sulfur involved the addition of two or three S atoms to the phosphinidene ligand to give new complexes identified as the dithiophosphinidene-bridged complex [MoReCp(μ-η(2):κ(2)(S,S′)-S(2)PR*)(CO)(5)], its dithiophosphonite-bridged isomer [MoReCp(μ-κ(2)(S,S′):κ(2)(S,S′)-S(2)PR*)(CO)(5)], or the trithiophosphonate-bridged derivative [MoReCp(μ-κ(2)(S,S′):κ(2)(S,S′)-S(3)PR*)(CO)(5)], all of them displaying novel coordination modes of their PRS(2) and PRS(3) ligands, as determined by X-ray diffraction studies. In contrast, the related MoMn complex yielded [MoMnCp(μ-η(2):η(2)-SPR*)(CO)(5)] under most conditions. A similar output was obtained in reactions with gray selenium for either MoRe or MoMn phosphinidene complexes, which under different conditions only gave the pentacarbonyl complexes [MoMCp(μ-η(2):η(2)-SePR*)(CO)(5)] (M = Re, Mn), these providing a new coordination mode for selenophosphinidene ligands.