AB-INITIO STUDY OF NUCLEAR MAGNETIC SHIELDINGS AND ULTRAVIOLET-SPECTRA FOR HYPOTHIOCYANITE AND ITS ISOMERS - THE MOLECULAR-STRUCTURE OF HYPOTHIOCYANITE

The C-13, N-15, O-17, and S-33 chemical shieldings for three optimized structures of hypothiocyanite have been calculated at the SCF, MP2, a nd CCSD levels using the gauge-including atomic-orbital approach. The first few excitation energies for the corresponding hypothiocyanous ac ids have been obtained using the equation-of-motion CCSD and the CI si ngles methods. Comparison of the calculated N-15 chemical shifts and o f the excitation spectra with experimental data suggests that hypothio cyanite has a bent OSCN- structure with C-s symmetry, even though the linear SNCO- isomer is 86 kJ/mol lower in energy. The linear ONCS- str ucture is 146 kJ/mol above SNCO-. No other low-lying structures were f ound.