Vibrational properties of some elusive members of the R-N=S=O family: CF3-N=S=O and SF5-N=S=O

ANDREA FLORES ANTOGNINI; HEINZ OBERHAMMER; EDGARDO HUGO CUTIN; NORMA LIS ROBLES

JOURNAL OF MOLECULAR STRUCTURE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 1023 p. 75 - 80

0022-2860

The vibrational spectra of N-(trifluoromethyl)sulfinylamine, CF3-N=S=O and N-(pentafluorsulfanyl)sulfinylamine,SF5-N=S=O have been recorded and assigned. According to quantum chemical calculations (B3LYP and MP2 with 6-31G(d) and 6-311+G(df) basis sets) the sterically unfavorable syn (Z-) conformers are 2.6?4.1 kcal/mol (CF3-N=S=O) and 3.1?4.6 kcal/mol (SF5-N=S=O) lower in free energy than the anti conformers. Such DeltaG° values determine an equilibrium of 98.8% (syn) and 1.2% (anti) for CF3-N=S=O, and 99% (syn) and < 1% (anti) for SF5-N=S=O (B3LYP and MP2 with 6-311+G(df) basis set). The presence of a single conformer is confirmed by the vibrational spectra. The syn structure of R-N=S=O compounds is stabilized by strong anomeric effects between the N and S electron lone pairs and the opposite N-R and S=O sigma* bonds. The bonding properties of some R-N=S=O and R-N=S=(O)F2 compounds are compared.