硅苯、1-硅萘及9-硅蒽的[4+4]二聚反应的比较研究

Comparative studies on the [4+4] dimerization reactions of silabenzene,1-silanaphthalene and 9-silaanthracene

采用密度泛函理论(DFT)在B3LYP/6-31G(d)水平上,研究硅苯、1-硅萘及9-硅蒽的[4+4]二聚反应的微观机理和势能剖面,考察了反应的取代基效应和溶剂效应。计算结果表明,所研究反应均为协同反应,且2个C-Si键同步形成。随反应物分子芳香环从小到大的增加,[4+4]反应在热力学和动力学上均变得越来越有利。硅苯中硅原子上具有吸电子性质的CCl_3及具有给电子性质的NH_2取代基,在热力学和动力学上均有利于反应。苯溶剂对所研究反应的势能剖面影响较小。

Density functional theory（DFT） calculation,at the B3LVP/6-31G（d） level of theory,were performed to investigate the mechanism, potential energy surface,substituent effect and solvent effect of[4~＋4]dimerization reactions of silabenzene,1-silanaphthalene and 9-silaanthracene.It can be found that all of studied reactions proceed in a concerted way and the formation of two C-Si bonds are synchronous. With the increase of magnitude of aromatic ring for reactant molecules,the reactions become much easier to proceed,both thermodynamically and kinetically.The substituent CCl_3 or NH_2 at Si atom of silabenzene is in favor of reactions,both thermodynamically and kinetically. Benzene,as a poor polar solvent,has only trivial influence on the potential energy surface of the studied reactions.