Structure and Conformations of N-(Fluoroformyl)imidosulfurous Dichloride, FC(O)NSCl2

• Published in: Inorganic chemistry 2003-06, Vol.42 (13), p.4071-4075
• Main Authors: Leibold, Christiane, Alvarez, Rosa M. S, Cutin, Edgardo H, Della Vedova, Carlos O, Oberhammer, Heinz
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic030058p

The IR (gas) and Raman (liquid) spectra of FC(O)NSCl2 demonstrate the presence of a conformational mixture in both phases. According to a gas electron diffraction study, the main conformer (94(8)%) possesses a syn−syn structure (C(O)F group synperiplanar with respect to the SCl2 bisector and the CO bond synperiplanar to the NS bond). Quantum chemical calculations (HF, B3LYP and MP2 with 6-31G* basis set, and MP2/6-311(2df)) predict a syn−anti structure for the second conformer. Analysis of the IR (gas) spectrum results in a contribution of 5(1)% of the minor form, corresponding to a Gibbs free energy difference ΔG° = G°(syn−anti) − G°(syn−syn) = 1.75(15) kcal/mol. This value is reproduced very well by quantum chemical calculations, which include electron correlation effects (ΔG° = 1.28−1.56 kcal/mol). The HF approximation overestimates this energy difference (ΔG° = 3.24 kcal/mol).