Chlorodifluoroacetyl Isothiocyanate, ClF2CC(O)NCS: Preparation and Structural and Spectroscopic Studies

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• 作者：Luis A. Ramos ; Sonia E. Ulic ; Rosana M. Romano ; Yury V. Vishnevskiy ; 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：2013
• 出版时间：July 11, 2013
• 年：2013
• 卷：117
• 期：27
• 页码：5597-5606
• 全文大小：424K
• 年卷期：v.117,no.27(July 11, 2013)
• ISSN：1520-5215

文摘

Chlorodifluoroacetyl isothiocyanate, ClF₂CC(O)NCS, was synthesized by the reaction of ClF₂CC(O)Cl with an excess of AgNCS. The colorless product melts at 鈭?5 掳C, and its vapor pressure follows the equation ln p = 鈭?471.1 (1/T) + 11.35 (p [atm], T [K]) in the range 鈭?8 to 22 掳C. The compound has been characterized by IR (gas phase, Ar matrix, and matrix photochemistry), by liquid Raman, by ¹⁹F and ¹³C NMR, gas UV鈥搗is, and photoelectron spectroscopy (PES), by photoionization mass spectrometry (PIMS), and by gas electron diffraction (GED). The conformational properties of ClF₂CC(O)NCS have been analyzed by joint application of vibrational spectroscopy, GED and quantum chemical calculations. The existence of two conformers has been detected in the gas and liquid phases, in which the C鈥揅l bond adopts a gauche orientation with respect to the C鈺怬 group; the C鈺怬 group is in syn- or anti-position with respect to the N鈺怌 double bond of the NCS group. The computed 螖G掳 difference between these two gauche鈥搒yn and gauche鈥揳nti forms is 螖G掳 = 0.63 kcal mol^鈥? in the B3LYP/6-31G(d) approximation. The most significant gas-phase structural parameters for gauche鈥搒yn ClF₂CC(O)NCS are r_e(NC鈺怱) 1.559(2) 脜, r_e(N鈺怌S) 1.213(2) 脜, r_e(N鈥擟) 1.399(7) 脜, r_e(C鈺怬) 1.199(2) 脜, and _e(CNC) 134.7(13)掳. Photolysis of ClF₂CC(O)NCS using an ArF excimer laser (193 nm) mainly yields ClF₂CNCS, CO, and ClC(O)CF₂NCS. The valence electronic properties of the title compound were studied using PES and PIMS. The experimental first vertical ionization energy of 10.43 eV corresponds to the ejection primarily of the sulfur lone-pair electrons of the in-plane nonbonding orbital on the NCS group.