Preparation and crystal structure of [WCl2(cp)2]+2[W4F18]2–(cp =η-C5H5) containing the new binary tungsten(IV) fluoride anion [W4F18]2–

Abstract

The metallocene [WCl₂(cp)₂](cp =η-C₅H₅) was treated with WF₆ in sulfur dioxide solution yielding the ionic complex species [WCl₂(cp)₂]⁺₂[W₄F₁₈]^2–1 and [WCl₂(cp)₂²⁺[WF₆]^–₂. Compound 1 was also obtained, in quantitative yield, from the reaction of elemental tungsten with two equivalents of [WCl₂(cp)₂] and three equivalents of WF₆. It crystallizes in the orthorhombic space group Pnma(no. 62) with cell parameters a= 13.625(5), b= 11.225(3) and c= 22.350(3)Å. The crystal data were collected at 23 °C and the final refinement values are R= 0.0308 and R′= 0.0341. The thermodynamics of the oxidation of [WCl₂(cp)₂] to give the tungsten(V) monocation in complex 1 are discussed on the basis of a Born–Haber cycle.