Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
J Phys Chem A. 2010 Aug 19;114(32):8480-7. doi: 10.1021/jp1063758.
Stabilizing effects in oxygenated thiane- and 1,3-dithiane-derived alpha-carbanions were investigated computationally. All isomers bearing sulfide, sulfoxide, and sulfone functional groups and combinations thereof were investigated by DFT calculations and NBO analyses. Their stabilities and the stereoelectronic effects present in these compounds were compared. Stabilizing effects of the respective functional groups were further estimated by calculation of isodesmic reactions. It turned out that n(C) --> sigma*(S-O) interactions, where both the n(C) and the S=O bond are in an antiperiplanar conformation, have the highest stabilizing effects. Similar stabilizing interactions are effective in carbanions with an equatorial lone pair at the carbon; here a productive n(C) --> sigma*(S-C) interaction is possible. n(C) --> sigma*(S-O) interactions, where the S=O bond is part of a sulfoxide are significantly more effective than in sulfones. Calculations of isodesmic reactions show similar trends but suggest the presence of additional electrostatic effects and possibly, to some extent, steric effects.
采用密度泛函理论（DFT）计算和自然键轨道（NBO）分析方法研究了含氧噻嗯和 1,3-二噻嗯衍生的α-碳负离子的稳定化效应。研究了所有带有硫醚、亚砜和砜官能团及其组合的异构体。比较了它们的稳定性和这些化合物中存在的立体电子效应。通过计算等电子反应进一步估计了各官能团的稳定化效应。结果表明，n(C) --> sigma*(S-O) 相互作用（其中 n(C) 和 S=O 键均呈反式构象）具有最高的稳定化效应。在具有碳上赤道孤对的碳负离子中，类似的稳定相互作用是有效的；这里可以形成有效的 n(C) --> sigma*(S-C) 相互作用。S=O 键为亚砜一部分的 n(C) --> sigma*(S-O) 相互作用比砜中的相互作用更有效。等电子反应的计算表明存在类似的趋势，但表明存在额外的静电效应，并且在某种程度上可能存在空间效应。
