Hydrostannylation of carbon dioxide by a hydridostannylene molybdenum complex.

Reaction of the aryltin(II) hydrides {ArSn(μ-H)} or {ArSn(μ-H)} (Ar = -CH-2,6-(CH-2,6-Pr), Ar = -CH-2,6-(CH-2,4,6-Pr)) with two equivalents of the molybdenum carbonyl [Mo(CO)(THF)] afforded the divalent tin hydride transition metal complexes, Mo(CO){Sn(Ar)H}, (1), or Mo(CO){Sn(Ar)(THF)H} (2), respectively. Complex 1 effects the facile hydrostannylation of carbon dioxide, to yield Mo(CO){Sn(Ar)(κ-O,O'-OCH)}, (3), which features a bidentate formate ligand coordinating the tin atom. Reaction of 3 with the pinacolborane, HBpin (pin = pinacolato) in benzene regenerated 1 in quantitative yield. All complexes were characterized by X-ray crystallography, as well as UV-visible, IR, and multinuclear NMR spectroscopies. The isolation of 1 and 2 is consistent with the existence of monomeric forms of {ArSn(μ-H)} and {ArSn(μ-H)} in solution. Regeneration of 1 from 3 reaction with pinacolborane as the hydrogen source shows the catalytic potential of 1 in the hydrogenation of CO.