N,N-Difluoro-O-trifluoromethyl-hydroxylamine, CF3ONF2: conformation and vibrational analysis studied by experimental and theoretical methods

Infrared spectra in the gas phase and in argon matrix and Raman spectra in the liquid phase were recorded for N,N-difluoro-Otrifluoromethyl- hydroxylamine, CF3ONF2. The presence of one single conformer could be demonstrated by heating the Ar/CF3ONF2 mixture at different temperatures between 20 and 245 8C with subsequent quenching of the mixture at 15 K as a matrix due to the absence of any change in the relative band intensities the IR matrix spectra. From quantum chemical calculations (B3LYP and B3PW91/6-311 þ G(3df) and MP2/6-311 þ G*), the syn conformation (syn orientation of the nitrogen lone pair with respect to the C–O bond, d(CON:) ¼ 08) is preferred. A second gauche inner form (d(CON:) ¼ 1658)) is calculated to be higher in energy by about 5 kcal/mol. The syn conformational preference is discussed in terms of the natural bond orbital population analysis. q 2004 Elsevier B.V. All rights reserved.