Synthesis, Characterization, and Lewis Acid Behavior of [W(NC6F5)F4] x and Computational Study of W(NR)F4 (R = H, F, CH3, CF3, C6H5, C6F5), W(NC6F5)F4(NCCH3), and W(NC6F5)F4(NC5H5) n ( n = 1, 2).

Amorphous [W(NC6F5)F4] x has been synthesized by the reaction of [C5H5NH][W(NC6F5)F5] with AsF5 in CH2Cl2. The reaction of [W(NC6F5)F4] x with CH3CN yields monomeric W(NC6F5)F4(NCCH3), whereas reaction with a sub-2-fold excess of C5H5N in CH3CN results in quantitative conversion to W(NC6F5)F4(NC5H5). Meanwhile, the reaction of W(NC6F5)F4(NCCH3) with a large excess of C5H5N results in the precipitation of W(NC6F5)F4(NC5H5)2. These compounds have been characterized in the solid state by Raman spectroscopy and in solution by multinuclear NMR spectroscopy. The crystal structures of W(NC6F5)F4(NCCH3) and W(NC6F5)F4(NC5H5), as well as improved structures of WOF4(NC5H5) n ( n = 1, 2), have been obtained at low temperatures. Furthermore, density functional theory (DFT-B3LYP) calculations have been conducted on the W(NR)F4 (R = H, F, CH3, CF3, C6H5, C6F5) series as well as W(NC6F5)F4(NCCH3) and W(NC6F5)F4(NC5H5) n ( n = 1, 2), providing optimized gas-phase geometries, vibrational frequencies, molecular orbitals, fluoride-ion affinities, and natural bond orbital (NBO) analyses.