Conformational stability of (chloromethyl) phosphonothioic difluoride fromtemperature-dependent infrared spectra of rare gas solutions and r(0) structural parameters

Variable temperature (-55 to - 150 degreesC) studies of the infrared spectr a (3500-400 cm(-1)) of (chloromethyl)phosphonothioic difluoride (ClCH2P(S)F -2) dissolved in liquid xenon and krypton have been recorded. From these da ta, the enthalpy difference has been determined to be 244 +/- 16 cm(-1) (2. 92 +/- 0.19 kJ mol(-1)) with the trans conformer being the more stable rota mer. Complete vibrational assignments are presented for both conformers, wh ich are consistent with the predicted wavenumbers obtained from ab initio M P2/6-31G(d) calculations utilizing two scaling factors. The optimized geome tries, conformational stabilities. harmonic force fields, infrared intensit ies, Raman activities and depolarization ratios have been obtained from RHF /6-31)(d) and/or MP2/6-31G(d) ab initio calculations. Hybrid density functi on theory (DFT) calculations to obtain the structural parameters and confor mational stability by the B3LYP/6-31G(d) method were also carried out. Thes e quantities are compared to the corresponding experimental quantities when appropriate as well as with some corresponding results for some similar mo lecules. The lb structural parameters have been obtained from a combination of the previously reported microwave rotational constants and ab initio MP 2/6-311+ G(d,p) predicted parameters. The results are compared to some corr esponding quantities for some similar molecules. (C) 2001 Elsevier Science B.V. All rights reserved.