Stabilization of [WF5 ]+ by Bidentate N-Donor Ligands.

Transition-metal hexafluorides do not exhibit fluoride-ion donor properties in the absence of donor ligands. We report the first synthesis of donor-stabilized [MF5 ]+ derived from a transition-metal hexafluoride via fluoride-ion abstraction using WF6 (L) (L=2,2'-bipy, 1,10-phen) and SbF5 (OSO) in SO2 . The [WF5 (L)][Sb2 F11 ] salts and [WF5 (1,10-phen)][SbF6 ]⋅SO2 have been characterized by X-ray crystallography, Raman spectroscopy, and multinuclear NMR spectroscopy. The reaction of WF6 (2,2'-bipy) with an equimolar amount of SbF5 (OSO) reveals an equilibrium between [WF5 (2,2'-bipy)]+ and the [WF4 (2,2'-bipy)2 ]2+ dication, as determined by 19 F NMR spectroscopy. The geometries of the cations in the solid state are reproduced by gas-phase geometry optimizations (DFT-B3LYP), and NBO analyses reveal that the positive charges of the cations are stabilized primarily by compensatory σ-electron donation from the N-donor ligands.