Structural and spectroscopic properties of complexes formed between HNCS and SO2 in low temperature matrices.

ABSTRACT

Matrix isolation FTIR spectroscopy has been combined with quantum chemical calculations in the aim to characterize complexes of isothiocyanic acid HNCS with SO2. The geometries of the 11, 12 and 21 complexes were optimized at the MP2 and DFT (B3LYPD3) levels of theory with the 6-311++G(3df,3pd) basis set. Five different HNCS⋯SO2 structures of the 11 stoichiometry were optimized. Three of them involve a weak NH⋯O hydrogen bond whereas two other geometries are stabilized by van der Waals interactions of various types. The HNCS/SO2/Ar spectra analysis evidences that at least one of the three hydrogen bonded structure is present after deposition of the matrices whereas the most stable van der Waals HNCS⋯SO2 structure as well as complexes of the 12 stoichiometry were detected upon annealing.