STRUCTURES AND VIBRATIONAL-SPECTRA FOR PROTONATED CARBONYL SULFIDE

The HOCS+ form of protonated OCS was identified in 1987 using high-res olution difference frequency laser spectroscopy by assigning the vibra tional frequency (nu = 3435 cm(-1)) as the O-H stretch. The isomer HSC O+ was not detected in spite of a search of the S-H stretching region. Theoretical calculations indicate, however, that the S-protonated for m lies significantly lower than the O-protonated form. To resolve this apparent discrepancy between experiments and theoretical calculations , highly accurate ab initio studies of both species have been carried out. Our results indicate that the S-protonated form lies about 5 kcal /mol mol below the O-protonated one. The SH stretching frequency is pr edicted to be found around 2496 cm(-1). A. new search for the nu(1) ba nd of HSCO+ using a diode spectrometer showed no evidence of HSCO+.