VIBRO-CONFORMATIONAL STUDY OF F2S(O)NCN - FTIR, PRERESONANCE RAMAN EFFECT, FORCE-FIELD AND THEORETICAL CALCULATIONS

The FTIR spectrum for vapour and the Raman spectrum for the liquid of difluorosulphenilimine cyanide (F2S(O)NCN) are presented. C-S symmetry is suggested for the main conformer in the liquid phase. Vibrational assignments are made for all but the torsional fundamental mode. The s ymmetry force constants were calculated using an approximate value for the torsion. The study was complemented by theoretical calculations a t various levels of sophistication. According to the ab initio methods (HF/3-21G, HF/6-31G*, MP2/6-31G*) two stable conformations of the co mpound exist in the gas phase. The main form possesses C-S symmetry (d elta(OSNC) = 180 degrees, trans), whilst for the less stable rotamer C -1 symmetry (delta(OSNC) = 4 to 26 degrees, near-cis) is predicted.