Pentafluoroethyl Derivatives of Sulfur(IV) Fluorides and the Diazabicyclo[2.2.2]octane-SF4 Lewis-Acid-Base System

Abstract

Pentafluoroethyl derivatives of sulfur(IV) fluorides were synthesized by reacting Me3SiC2F5 with SF4 and SOF2 forming SF3C2F5, SF2(C2F4)2, SOFC2F5, and SO(C2F5)2, all of which were modelled by B3LYP/aug-cc-PVTZ calculations and characterized by high-resolution fluorine-19 NMR spectroscopy including simulations of their complicated 19F NMR spectra. The X-ray crystal structures of SO(C2F5)2, Me3SiC2F5, and [S(OC2H5)3][H3F4] were determined, the latter being formed by the low-temperature alcoholysis of some sulfur(IV) species. The diazabicyclo[2.2.2]octane-SF4 Lewis acid-base system was investigated using Raman spectroscopy, including the formation of C6H12N2•2SF4 that was characterized by X-ray crystallography. When precipitated at low temperature, the DABCO-SF4 system incorporates additional non-adducted SF4 in the solid. Removing some SF4 under dynamic vacuum at –25 °C still left SF4 in the sample, presumably yielding the DABCO•SF4 adduct, based on Raman spectroscopy. The DABCO-SF4 system can be solvolysed by HF that is produced by the hydrolysis of SF4, forming crystals of [C6H12N2H]2F[SF5]•6SF4.