CEQUINOR (UNLP-CONICET, CCT-La Plata), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, 1900 La Plata, República Argentina.
J Phys Chem A. 2013 Jul 11;117(27):5597-606. doi: 10.1021/jp403549f. Epub 2013 Jul 2.
Chlorodifluoroacetyl isothiocyanate, ClF2CC(O)NCS, was synthesized by the reaction of ClF2CC(O)Cl with an excess of AgNCS. The colorless product melts at -85 °C, and its vapor pressure follows the equation ln p = -4471.1 (1/T) + 11.35 (p [atm], T [K]) in the range -38 to 22 °C. The compound has been characterized by IR (gas phase, Ar matrix, and matrix photochemistry), by liquid Raman, by (19)F and (13)C NMR, gas UV-vis, 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-Cl bond adopts a gauche orientation with respect to the C═O group; the C═O group is in syn- or anti-position with respect to the N═C double bond of the NCS group. The computed ΔG° difference between these two gauche-syn and gauche-anti forms is ΔG° = 0.63 kcal mol(-1) in the B3LYP/6-31G(d) approximation. The most significant gas-phase structural parameters for gauche-syn ClF2CC(O)NCS are re(NC═S) 1.559(2) Å, re(N═CS) 1.213(2) Å, re(N-C) 1.399(7) Å, re(C═O) 1.199(2) Å, and ∠e(CNC) 134.7(13)°. 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.
氯二氟乙酰基异硫氰酸酯，ClF2CC(O)NCS，是由 ClF2CC(O)Cl 与过量的 AgNCS 反应合成的。无色产物在-85°C 下熔化，其蒸气压在-38 至 22°C 范围内遵循 ln p = -4471.1 (1/T) + 11.35 (p [atm], T [K])的方程。该化合物已通过红外（气相、Ar 基质和基质光化学）、液体拉曼、(19)F 和(13)C NMR、气体紫外可见光谱和光电子能谱（PES）、光电离质谱（PIMS）和电子衍射（GED）进行了表征。ClF2CC(O)NCS 的构象特性已通过振动光谱、GED 和量子化学计算的联合应用进行了分析。在气相和液相中检测到两种构象的存在，其中 C-Cl 键相对于 C=O 基团呈 gauche 取向；C=O 基团与 NCS 基团的 N=C 双键处于顺式或反式位置。在 B3LYP/6-31G(d)近似值下，这两种 gauche-syn 和 gauche-anti 形式之间的计算ΔG°差为ΔG°=0.63 kcal mol(-1)。gauche-syn ClF2CC(O)NCS 的最重要气相结构参数为 re(NC═S) 1.559(2)Å、re(N═CS) 1.213(2)Å、re(N-C) 1.399(7)Å、re(C═O) 1.199(2)Å 和 ∠e(CNC) 134.7(13)°。使用 ArF 准分子激光器（193nm）光解 ClF2CC(O)NCS 主要生成 ClF2CNCS、CO 和 ClC(O)CF2NCS。使用 PES 和 PIMS 研究了标题化合物的价电子性质。实验得到的第一垂直电离能 10.43eV 主要对应于平面非键轨道上 NCS 基团的硫孤对电子的逐出。
