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

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.