Haerizade Bibi Narjes, Kassaee Mohammad Zaman, Koohi Maryam, Ghavami Monire, Zandi Hassan
Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
Comb Chem High Throughput Screen. 2014;17(8):674-80. doi: 10.2174/1386207317666140422155343.
In our continued quest for novel stable carbenes, silylenes, and germylenes, here we compare and contrast multiplicities and relative stabilities of carbenes affected with four different α-ylides. The latter include carbon, immonium, phosphorus, and sulfur ylides substituted at the alpha positions of carbenes with acyclic, cyclic and cyclicunsaturated structural frameworks. Related thermodynamic data are calculated at B3LYP/6-311++G**//B3LYP/6-31+G* and B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G* levels. Investigations reveal the enlargement of the singlet-triplet energy gaps (ΔΕs-t) in the order of immonium > phosphorus > sulfur > carbon. The observed trend, which is taken as an indication of stability, is thoroughly analyzed by applying appropriate isodesmic reactions which differentiate the substituent effects on each of our singlet or triplet carbene. The effect of unsaturation is also probed in each series of the ylide carbenes. The reactivity of the species is discussed in terms of nucleophilicity and electrophilicity.
在我们对新型稳定卡宾、硅烯和锗烯的持续探索中，在此我们比较并对比了受四种不同α-叶立德影响的卡宾的多重性和相对稳定性。后者包括在卡宾的α位被无环、环状和环状不饱和结构骨架取代的碳叶立德、亚胺叶立德、磷叶立德和硫叶立德。相关热力学数据在B3LYP/6 - 311++G**//B3LYP/6 - 31+G和B3LYP/AUG - cc - pVTZ//B3LYP/6 - 31+G水平上计算。研究表明，单重态 - 三重态能隙（ΔΕs - t）按亚胺叶立德＞磷叶立德＞硫叶立德＞碳叶立德的顺序增大。通过应用适当的等键反应对观察到的趋势（被视为稳定性的一种指示）进行了深入分析，这些反应区分了对我们的每个单重态或三重态卡宾的取代基效应。在每一系列叶立德卡宾中也探究了不饱和性的影响。根据亲核性和亲电性讨论了这些物种的反应性。
