Syntheses and Characterization of W(NC6F5)F5- and W2(NC6F5)2F9- Salts and Computational Studies of the W(NR)F5- (R = H, F, CH3, CF3, C6H5, C6F5) and W2(NC6F5)2F9- Anions.

Abstract

Convenient preparative routes to fluorido[(pentafluorophenyl)imido]tungstate(VI) salts have been developed. The reaction of WF6·NC5H5 or [N(CH3)4][WF7] with C6F5NH2 results in quantitative formation of the C5H5NH+ or N(CH3)4+ salt of the W(NC6F5)F5- anion, respectively. The dissolution of [C5H5NH][W(NC6F5)F5] in anhydrous HF results in the formation of [C5H5NH][W2(NC6F5)2F9]. These salts have been comprehensively characterized in the solid state by X-ray crystallography and Raman spectroscopy and in solution by 19F and 1H NMR spectroscopy. The crystal structures of the W(NC6F5)F5- salts reveal conformational differences in the anions, and the 19F NMR spectra of these salts in CH3CN reveal coupling of the axial fluorido ligand to the 14N nucleus of the imido ligand. In addition, density functional theory (DFT-B3LYP) calculations have been performed on a series of W(NR)F5- anions (R = H, F, CH3, CF3, C6H5, C6F5) and the W2(NC6F5)2F9- anion, including gas-phase geometry optimizations, vibrational frequencies, molecular orbitals, and natural bond orbital (NBO) analyses.