The unusual structure of the novel [Mo2Cp2Cl5]– ion (Cp = C5H5)

Abstract

The novel [Mo₂Cp₂Cl₅]^– ion (Cp = C₅H₅), obtained as the salt of the bis(triphenylphosphine)iminium (PPN) cation on reacting MoCpCl₂ with PPN⁺Cl^– in CH₂Cl₂, contains two equivalent molybdenum centres at a distance of 2.413(1)Å, which are bonded to two terminal Cl atoms and one η⁵-C₅H₅ group and are bridged by a single Cl ligand; the electronic structure indicates a metal-metal triple bond, which is little perturbed by the bridging chloride ligand; the molecule provides a bridge between two diverse structures of M₂(η⁵-C₅H₄Prⁱ)₂Cl₄(M = Mo: quad ruply-bridged, Mo–Mo single bond; M = W: unbridged, W–W triple bond).