Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen, LXXXII. Zweikernige μ‐Benzylidin‐Komplexe mit Doppelbindung zwischen Rheniumatomen

Multiple Bonds Between Main‐Group Elements and Transition Metals, LXXXII. — Dinuclear p‐Benzylidyne Complexes Having a Double Bond between Rhenium Atoms The dialkylrhenium(V) complex (η⁵‐C₅Me₅)Re(O)(CH₂Ph)₂ (3) reacts with the organotitanium reagents (η⁵‐C₅H₅)TiX₃ (X  Cl, Br) to yield the dinuclear rhenium(IV) complexes (η⁵C₅Me₅)₂ Re₂X₃(CC₆H₅) (4a, b). According to a single‐crystal X‐ray diffraction analysis, 4a′ (C₅Me₄Et in place of C₅Me₅) represents one of the few known examples of μ‐alkylidyne complexes that have metal‐to‐metal multiple bonds. The molecule of C₂ symmetry has a planar four‐membered Re,Cl,Re′,C‐ring geometry and two trans‐oriented sets of ligands. Very small angles at the bridging chloro ligand and alkylidyne carbon atom result from the short metal‐metal distance (double bond).