Vibrational Spectra, Crystal Structures, Constitutional and Rotational Isomerism of FC(O)SCN and FC(O)NCS

Abstract:

Fluorocarbonyl thio- and isothiocyanate, FC(O)SCN and FC(O)NCS, were fully characterized by IR (gas, Ar and N2 matrixes), Raman (liquid and solid), UV (gas), and 13C NMR (liquid) spectroscopy, as well as single-crystal X-ray diffraction. Their vibrational and conformational properties were analyzed using matrix isolation techniques guided by quantum chemical calculation at the ab initio [MP2 and CCSD(T)], density functional theory B3LYP, and CBS-QB3 levels of theory. A complete assignment of the fundamental modes of FC(O)SCN was performed. In both the gas and liquid states, FC(O)SCN and FC(O)NCS were found to exist as two conformers (Cs symmetry), in which the carbonyl double bond (CO) adopts a synperiplanar (syn) and an antiperiplanar (anti) orientation with respect to either the SCN or NCS group. For FC(O)SCN, the conformational enthalpy difference, ΔH° = H°(anti) − H°(syn), was …

Año de publicación:

2010

Keywords:

Fuente:

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