Ph(SiMe_(2))nPh体系π→π*UV谱的研究

A Study of UV Spectra of Ph-(SiMe)-Ph with π→π* Transitions

本文依据Spin-Free理论,使用Gelfand基构造多电子波函数,采用四轨道模型,对Ph(SiMe_(2))nPh体系(n=1~6)的π→π*跃迁进行了EHMO-CI计算,所得第一及第二跃迁能与UV谱的实验结果基本一致。当体系硅链原子数增加时,第一吸收带红移的现象起因于LUMO中d轨道成份增加,导致电子排斥作用变化。在LUMO中,硅链上的d轨道以πd的形式与苯环π*轨道进行πd—π*共轭互相作用,这种作用很可能与第一吸收带的强度有内在的联系。

The UV Spectra of Ph(SiMe_(2))nPh with n = 1,2,3,4,5,6 are analyzed by means of the EHMO-CI-SPIN-FREE method with four-orbital models.The first and the second absorption bands arise in essence from the π→π* transitions. Furthermore, the d atomic orbitals of silicon chain, which may play an important role in the red shift of first absoption bands, are discussed.