TAUTOMERISM, PHOTOTAUTOMERISM AND INFRARED-SPECTRA OF MATRIX-ISOLATED2-QUINOLINETHIONE

The IR spectra of thione and thiol tautomers of 2-quinolinethione isol ated in Ar and Nz low-temperature matrices are reported. The UV-induce d photochemical reaction, transforming the initially abundant thione f orm into the thiol form, was used for separation of the spectra of the two tautomers. The ratio of the tautomers before UV irradiation of th e sample was estimated as [thione]/[thiol] = 7:1. The experimental spe ctra of 2(1H)-quinolinethione and 2-quinolinethiol were interpreted by comparison with the spectra calculated theoretically at the ab initio SCF/6-31G* level.