Synthesis of zerovalent bis(η-arene) compounds of zirconium, hafnium, niobium, tantalum, and tungsten using the metal vapours

Abstract

Co-condensation of the vapours of the metals niobium, tantalum, and tungsten, derived from a positive hearth electron-gun furnace, with an excess of arenes gives the bis(η-arene) compounds [M(η-arene)₂](M = Nb, Ta, or W). Similarly, zirconium and hafnium vapours with a mixture of arenes and trimethylphosphine give the bent bis(η-arene) compounds [M(η-arene)₂(PMe₃)](M = Zr and Hf). The bis(η-arene)tungsten compounds protonate readily in dilute aqueous acids to form the bent bis(η-arene)hydrido-cations [W(η-arene)₂H][PF₆]. Spectroscopic properties and other characterising data are presented for the new compounds.