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Matrix photochemistry at low temperatures and spectroscopic properties of γ-butyrothiolactone

Abstract:

The five-membered heterocyclic γ-butyrothiolactone was isolated in a low-temperature, inert Ar matrix, and the UV-visible (200-800 nm)-induced photochemistry was studied. On the basis of the IR spectra, the formation of ethylketene (CH3CH2CH-C-O) was identified as the main channel of photodecomposition. The valence electronic structure was investigated by He(I) photoelectron spectroscopy assisted by quantum chemical calculations at the outer valence Green's function/6-311++G(d,p) level of theory. The first three bands at 9.54, 9.69, and 11.89 eV are assigned to the nS, nO, and C-O orbitals, respectively, denoting the importance of the-SC(O)- group in the outermost electronic properties. The conventional ring strain energy was determined to be 3.8 kcal mol-1 at the G2MP2 level of calculation within the hyperhomodesmotic model. © 2010 American Chemical Society.