title: Structure and conformations of N-(fluoroformyl)imidosulfurous dichloride, FC(O)N=SCl2.
abstract: The IR (gas) and Raman (liquid) spectra of FC(O)NSCl(2) 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 SCl(2) 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 DeltaG degrees = G degrees (syn-anti) - G degrees (syn-syn) = 1.75(15) kcal/mol. This value is reproduced very well by quantum chemical calculations, which include electron correlation effects (DeltaG degrees = 1.28-1.56 kcal/mol). The HF approximation overestimates this energy difference (DeltaG degrees = 3.24 kcal/mol).
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Tübingen, 72076 Tübingen, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Leibold
authors.forename: Rosa M S
authors.initials: RM
authors.lastname: Alvarez
authors.forename: Edgardo H
authors.initials: EH
authors.lastname: Cutin
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Della Vedova
authors.forename: Heinz
authors.initials: H
authors.lastname: Oberhammer