17O and 33S nuclear magnetic shielding of sulfur trioxides from the experimental measurements and theoretical calculations

Abstract

In a recent (17)O NMR spectra of liquid sulfur trioxide, several unexpected peaks appeared with the temperature-dependent integrated peak ratio. In order to interpret NMR spectra and assign peaks to possible molecular structures, the theoretical quantum mechanical density functional theory and Møller-Plesset second-order perturbation theory calculations were performed. It is suggested that in the liquid sulfur trioxide, apart from monomeric SO3, a significant amount of (SO3)3 cyclic trimers should appear. No theoretical data support hypothesis on (SO3)2 dimers formation.

Keywords: 17O and 33S; NMR spectra; ab initio shielding calculations; sulfur oxides.