Chlorodifluoroacetyl Isocyanate, ClF2CC(O)NCO: Preparation and Structural and Spectroscopic Studies

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• 作者：Luis A. Ramos ; Sonia E. Ulic ; Rosana M. Romano ; Yury V. Vishnevskiy ; Raphael J. F. Berger ; Norbert W. Mitzel ; Helmut Beckers ; Helge Willner ; Shengrui Tong ; Maofa Ge ; Carlos O. Della V茅dova
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：November 29, 2012
• 年：2012
• 卷：116
• 期：47
• 页码：11586-11595
• 全文大小：456K
• 年卷期：v.116,no.47(November 29, 2012)
• ISSN：1520-5215

文摘

Chlorodifluoroacetyl isocyanate, ClF₂CC(O)NCO, was prepared by the reaction of ClF₂CC(O)Cl with excess of AgNCO. The colorless compound melts at 鈭?3 掳C and the vapor pressure follows the equation ln p = 鈭?868.3 (1/T) + 10.89 (p [Atm], T [K]) in the range 鈭?8 to +22 掳C, extrapolated bp ca. 82 掳C. It has been characterized by IR (gas phase, Ar matrix), liquid Raman, ¹⁹F and ¹³C NMR, gas UV鈥搗is spectrum, photoelectron spectroscopy (PES), photoionization mass spectrometry (PIMS), and gas electron diffraction (GED). The matrix photochemistry has been studied and the conformational properties of ClF₂CC(O)NCO have been analyzed by joint application of vibrational spectroscopy, GED, and quantum chemical calculations. Two conformers were detected in gaseous and liquid phases, in which the C鈥揅l bond adopts a gauche orientation with respect to the C鈺怬 group, whereas this group can be in syn or anti orientation with respect to the N鈺怌 bond of the NCO group. An enthalpy difference 螖H_exp^掳 = 1.3 卤 0.2 kcal mol^鈥? between the most stable syn鈥揼auche and the less stable anti-gauche form was derived using the van鈥檛 Hoff equation, which is in reasonable agreement with the computed difference of 螖H掳 = 0.8 kcal mol^鈥? (B3LYP/6-311+G(3df) approximation). The most significant gas phase structural parameters for gauche鈥搒yn ClF₂CC(O)NCO are r_e(NC鈺怬) = 1.157(1) 脜, r_e(N鈺怌O) = 1.218(1) 脜, r_e(N鈥揅) = 1.378(9) 脜, r_e(C鈺怬) = 1.195(1) 脜, _e(CNC) = 128.6(19)掳. Photolysis of ClF₂CC(O)NCO using an ArF excimer laser (193 nm) mainly yield ClF₂CNCO along with some ClF₂CC(O)N nitrene. The valence electronic properties of the title compound were studied using the PES and PIMS. The experimental first vertical ionization energy of 11.54 eV corresponds to the ejection of a carbonylic oxygen lone pair electron.