Tetramethylammonium bifluoride, crystal structure and vibrational spectra

Abstract

Single crystals of [N(CH 3 ) 4 ]HF 2 were obtained as a by-product during the recrystallization of [N(CH 3 ) 4 ]ClF 4 from CH 3 CN solution. X-ray diffraction data show that [N(CH 3 ) 4 ]HF 2 crystallizes in the orthorhombic space group Pmn2 1 with Z = 2 and unit cell dimensions a = 6.611(5), b = 8.753(5), and c = 5.386(4) Å. The structure was solved by direct methods and refined by least squares to a final R = 0.055 by using 205 independent reflections. The HF 2 − anions are symmetric, exhibit an unusually short [Formula: see text] distance of 2.213(4) Å, and vibrational frequencies close to those of the free HF 2 − anion. Keywords: tetramethylammonium bifluoride, crystal structure, Raman spectrum.