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Matrix photochemical study and conformational analysis of CH 3C(O)NCS and CF3C(O)NCS

Abstract:

The vapor of acetyl isocyanide, CH<inf>3</inf>C(O)NCS, and trifluoroacetyl isocyanide, CF<inf>3</inf>C(O)NCS, were isolated in solid Ar at 15 K. The existence of rotational isomerism was confirmed when the matrixes were irradiated with broad-band UV-vis light (200 ≤ λ ≤ 800 nm) and also by temperature-dependent Ar-matrix IR spectroscopy. The initial spectra showed the vapor of CH<inf>3</inf>C(O)NCS and CF<inf>3</inf>C(O)NCS consist of two conformers syn-syn and syn-anti (with the C-O bond syn with respect to the C-H or C-F bond and syn or anti with respect to the N-C double bond). When CH <inf>3</inf>C(O)NCS is irradiated, simultaneously with the randomization process, H<inf>2</inf>CCO and HSCN are produced. In the case of the photolysis of CF<inf>3</inf>C(O)NCS, the main products are CF<inf>3</inf>NCS and CO. The assignment of the IR bands to the different photoproducts was made on the basis of the usual criteria, taking account reported antecedents in the literature. © 2013 American Chemical Society.