An unexpected explanation for the unsymmetrically bridging alkyne ligand in [W2(η-C5H4Pri)2Br4(µ-C2Ph2)]

Abstract

Extended-Hückel molecular-orbital calculations have been performed for the recently reported alkyne complex [W₂(η-C₅H₄Prⁱ)₂Br₄(µ-C₂Ph₂)], in which the µ-C₂Ph₂ ligand is substantially distorted from the ideal perpendicular-bridging geometry by 26°. In contrast to other distorted µ-alkyne complexes for which the bonding has been analysed, the deviation of the alkyne ligand from perpendicularity does not arise from the anticipated second-order Jahn–Teller effect.