Crystal structure of [W(η-C6F6)2] synthesised together with other sandwich complexes of tungsten and molybdenum containing η6-C6F6 or η6-C6H3F3-1,3,5 ligands, from atoms of the metals

Abstract

Reaction of molybdenum or tungsten atoms with hexafluorobenzene or 1,3,5-trifluorobenzene or with mixtures of these ligands and benzene or 1,3,5-trimethylbenzene gave the new compounds [M(C₆F₆)₂], [M(C₆H₃F₃-1,3,5)₂], [M(C₆F₆)(C₆H₆)], [M(C₆F₆)(C₆H₃F₃-1,3,5)] and [M(C₆F₆)(C₆H₃Me₃-1,3,5)](M = Mo or W) in yields ranging from <1 to 5% as stable crystalline solids. A single-crystal X-ray study of [W(C₆F₆)₂] showed it to have the same symmetry as [Cr(C₆H₆)₂] and the same W–C bond lengths as in [W(C₆H₅Me)₂]. The ¹⁹F and ¹H NMR spectra of the mixed-ligand products show interring coupling with large coupling constants which make some of the spectra exceptionally easy to interpret.