MG12 15min4:38
THE GROUND-STATE OF PROTONATED CARBONYL SULFIDE, HOCS+ OR OCSH+?.

MARIA M. SANZ, CHANGHONG XIA, STEPHEN C. FOSTER AND SVEIN SAEBO, Department of Chemistry, Mississippi State University Mississippi State, MS 39762-9573.

Ab initio calculation by Scarlett and Taylor predicted that S-protonated OCS is more stable than the O-protonated isomer. Experimental evidence appears to contradict this finding. Nakanaga and Amano observed a band of protonated OCS at 3435 cm-1 and assigned it to the O-H stretching vibration. Although they also searched near 2500 cm-1, they didn't observe any spectrum which could be attributed to an S-protonated isomer.

We have carried out ab initio calculation at the MP2/6-311G++(2df,2pd) and QCISD levels and have confirmed the conclusions of Scarlett and Taylor. The S-protonated form is predicted to be more than 4 kcal/mol more stable than the O-protonated isomer. This calculation and the results of our experimental search for the S-protonated will be reported.