Chromium, molybdenum and tungsten carbonyl derivatives of distibinomethane ligands†

Abstract

Substituted Group 6 carbonyl complexes of the distibinomethane ligands Ph₂SbCH₂SbPh₂ (dpsm) and Me₂SbCH₂SbMe₂ (dmsm) of types [M(CO)₅(η¹-dpsm)] (M = Cr, Mo or W), [(OC)₅M(µ-dpsm)M(CO)₅] (M ≠ Mo), [(OC)₅M(µ-dmsm)M(CO)₅], [(OC)₄M(µ-dpsm)₂M(CO)₄], [(OC)₄M(µ-dmsm)₂M(CO)₄] and fac-[M(CO)₃(η¹-dpsm)₃] have been isolated and characterised by chemical analysis, IR, NMR (¹H, ¹³C-{¹H}, ⁹⁵Mo) spectroscopy and FAB mass spectrometry. The crystal structures of [W(CO)₅(dpsm)], [{W(CO)₅}₂(dpsm)], [{W(CO)₄(dpsm)}₂] and [{W(CO)₄(dmsm)}₂] have been determined. Complexes of η¹-dmsm have been observed but are too unstable to isolate in a pure state. Both the ligands function as monodentate or bridging bidentates in the complexes characterised, but no examples with chelated distibinomethanes have been prepared. Comparisons are drawn with complexes of related diphosphine ligands.