Synthesis of η-cyclopentadienyl-polyborane derivatives of molybdenum and tungsten

Abstract

The reaction of LiBH₄ with [Mo(η-C₅H₄Me)Cl₄] gives the dimetallaborane bicapped closo-[{Mo(η-C₅H₄R)}₂B₅H₉], which has been characterised by X-ray crystallography. The reaction of LiBH₄ with [W(η-C₅H₄R)Cl₄], for R = Me, gives closo-[{W(η-C₅H₄Me)H₂}₂B₃H₇] or, for R = Prⁱ, both closo-[{W(η-C₅H₄Prⁱ)H₂}₂}B₃H₇] and nido-[{W(η-C₅H₄Prⁱ)H₃}B₄H₈]. The reaction between [Mo(η-C₅H₄Me)(PMe₃)₂Cl₂] and LiBH₄ yields bicapped closo-[{Mo(η-C₅H₄Me)}₂B₅H₉] or nido-[{Mo(η-C₅H₄Me)(PMe₃)H}B₄H₈], depending on the reaction conditions. Also LiBH₄ reacts with [W(PMe₃)₃Cl₄] to give a mixture of nido-[{W(PMe₃)₂H₄}B₄H₈] and arachno-[{W(PMe₃)₃H₃}B₃H₈].