Zeng Xiaoqing, Ge Maofa, Sun Zheng, Wang Dianxun
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
J Phys Chem A. 2006 May 4;110(17):5685-91. doi: 10.1021/jp061050e.
Bis(trifluoroaceto) disulfide CF(3)C(O)OSSOC(O)CF(3) was prepared and studied by Raman, photoelectron spectroscopy (PES), and theoretical calculations. This molecule exhibits gauche conformation with both C=O groups cis to the S-S bond; the structure of the OSSO moiety is characterized by dihedral angle delta(OSSO) = -95.1 degrees due to the sulfur-sulfur lone pair interactions. The contracted S-S bond (1.979 Angstroms) and relatively high rotational barrier (19.29 kcal mol(-1) at the B3LYP/6-31G level) of the delta(OSSO) indicate the partial resonance-induced double bond character in this molecule. After ionization, the ground cationic-radical form of CF(3)C(O)OSSOC(O)CF(3)(*+) adopts a trans planar main-atom structure (delta(OSSO) = 180 degrees and delta(OCOS) = 0 degrees ) with C(2)(h) symmetry. The S-S bond elongates to 2.054 Angstroms, while the S-O bond shortens from 1.755 Angstroms in neutral form to 1.684 Angstroms in its corresponding cationic-radical form. The adiabatic ionization energy of 9.91 eV was obtained accordingly. The first two HOMOs correspond to the electrons mainly localized on the sulfur 3p lone pair MOs: 3ppi {36a (n(A)(S))](-1) and 3ppi 35b (n(B)(S), n(B)(O(C)(=)(O))), with an experimental energy separation of 0.16 eV. The first vertical ionization energy is determined to be 10.81 eV.
双（三氟乙酰基）二硫化物CF(3)C(O)OSSOC(O)CF(3) 已通过拉曼光谱、光电子能谱（PES）和理论计算进行了制备和研究。该分子呈现出 gauche 构象，两个 C=O 基团均与 S-S 键呈顺式；由于硫-硫孤对相互作用，OSSO 部分的结构以二面角 δ(OSSO) = -95.1°为特征。收缩的 S-S 键（1.979 埃）和 δ(OSSO) 相对较高的旋转势垒（在 B3LYP/6-31G 水平下为 19.29 kcal mol(-1)）表明该分子中存在部分共振诱导的双键特征。电离后，CF(3)C(O)OSSOC(O)CF(3)(*+) 的基态阳离子自由基形式采用具有 C(2)(h) 对称性的反式平面主原子结构（δ(OSSO) = 180°且 δ(OCOS) = 0°）。S-S 键伸长至 2.054 埃，而 S-O 键从中性形式的 1.755 埃缩短至其相应阳离子自由基形式的 1.684 埃。据此获得的绝热电离能为 9.91 eV。前两个最高占据分子轨道（HOMO）对应于主要定域在硫 3p 孤对分子轨道上的电子：3ppi {36a (n(A)(S))](-1) 和 3ppi 35b (n(B)(S), n(B)(O(C)(=)(O)))，实验能量间隔为 0.16 eV。确定的第一垂直电离能为 10.81 eV。
