Vibrational spectra and normal coordinate analysis of CF 3 compounds : XXXIV. The bis(trifluoromethyl)difluoroborate anion: X-ray structure of Cs[(CF 3) 2BF 2

Abstract

The 10B and 11B IR and Raman spectra of the [(CF 3) 2BF 2] − anion are reported, assigned, and used to determine a quadratic local symmetry force field via a normal coordinate analysis. The crystal structure of Cs[(CF 3) 2BF 2] ( P2 1/ m, a 5.958(1), b 7.628(1), c 8.2997(9) Å, β 100.50(1)°, Z = 2, d c 2.863 g cm −3 has been determined by X-ray diffractometry. The most important force constants are f(BC) 3.68 × 10 2, f(BF) 4.17 × 10 2 and f(CF) 4.85 × 10 2 N/m, the respective mean bond lenghts being 1.618, 1.391 and 1.353 Å. The FBF and CBC bond angles are 108.1(4) and 113.6(5)°, respectively. Apparently because of Cs⋯F(B, C) interactions, one BC bond has a staggered and the other an eclipsed conformation in the solid state.