环体聚硅氧烷D_4~H的密度泛函研究

DFT study on 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane

采用B3LYP/6-311++G(d,p)方法,对环体聚硅氧烷D4H进行了量子化学研究。优化了D4H的几何构型,研究了目标化合物在几何结构、电子结构、偶极距、前线轨道等方面的性质。结果表明,D4H分子中Si-O八元环采取"椅式-船式"低能构象。Si原子上集中了大部分的正电荷,而O、C原子则带负电荷。各原子对分子HOMO、LUMO贡献的区别并不明显,HOMO、LUMO能量差较大,表明分子具有一定的稳定性。溶剂效应分析表明,随着溶剂极性的增加,分子的能量越来越小,稳定性增加。

B3LYP/6-311-H-G（d,p） was conducted on 1,3,5,7-tetrahydrogen-l,3,5,7-tetramethylcyclotetrasiloxane, including geometry conformation, electronic structures, dipole and frontier orbitals. The results showed that a ＂chair-boat＂ conformation was preferred. The positive charge located on Si and the negative charge located on O, C. There was no obvious difference between atoms concerning their contribution to the HOMO and LUMO. The large gap between HOMO and LUMO indicated the stability of title compound. With the increase of the polarity of solvent, stability of title compound increased.