INFRARED MATRIX-ISOLATION AND THEORETICAL-STUDIES OF SO2-HNO3 AND SO2-HONO SYSTEMS

Argon matrix infrared spectra of sulphur dioxide complexes with nitric or nitrous acid indicate formation of hydrogen-bonded structures. The red shifts of the OH stretching modes are equal to ca. 179, 51 and 40 cm(-1) in SO2-HNO3, SO2-HONO-trans and SO2-HONO-cis complexes, respec tively. Theoretical studies of the structure and spectral characterist ics of the title complexes were carried out on the electron correlatio n level with 6-31G(d) basis set. For all studied systems only one stab le structure was found with the OH group interacting with one oxygen a tom of the sulphur dioxide molecule. The calculated infrared spectra r eproduce well the frequencies and the intensities of the measured spec tra. (C) 1998 Elsevier Science B.V.