Electronic Transitions in Conformationally Controlled Peralkylated Hexasilanes
Electronic Transitions in Conformationally Controlled Peralkylated Hexasilanes
复制标题
构象控制的全烷基化六硅烷中的电子跃迁
DOI：
10.1002/cphc.201600633
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发表时间：
2016
期刊：
影响因子：
2.9
通讯作者：
Michl, Josef
中科院分区：
文献类型：
--
作者：
Kanazawa, Yuki;Tsuji, Hayato;Ehara, Masahiro;Fukuda, Ryoichi;Casher, Deborah L.;Tamao, Kohei;Nakatsuji, Hiroshi;Michl, Josef
由于σ电子离域，低聚硅烷的物理化学性质显示出独特的构象依赖性。利用紫外吸收光谱、磁性圆二色性光谱和线性二色性光谱研究了SiSiSiSi二面角被控制为asyn（S）、anti（A）和oreclipsed（E）构象的全烷基化正己硅烷的SAS、AAS和AEA构象的激发态.同时高斯拟合的所有三个光谱确定了一组最小的过渡和波数，振子强度，和MCDB条款在所有三种化合物。结果与使用对称性调整的簇组态相互作用方法获得的结果进行了比较，并且与使用PBE 0泛函的含时密度泛函理论获得的结果几乎一样好。还研究了自由链全甲基化正己硅烷（n-Si 6 Me 14）的跃迁能和其他性质的构象依赖性作为二面角的函数，发现的显著效应归因于避免了σσ* 和σπ* 特征构型之间的交叉。
The photophysical properties of oligosilanes show unique conformational dependence due to σ‐electron delocalization. The excited states of the SAS, AAS, and AEA conformations of peralkylatedn‐hexasilanes, in which the SiSiSiSi dihedral angles are controlled into asyn(S),anti(A), oreclipsed(E) conformation, were investigated by using UV absorption, magnetic circular dichroism (MCD), and linear dichroism spectroscopy. Simultaneous Gaussian fitting of all three spectra identified a minimal set of transitions and the wavenumbers, oscillator strengths, and MCDBterms in all three compounds. The results compare well with those obtained by using the symmetry‐adapted‐cluster configuration interaction method and almost as well with those obtained by time‐dependent density functional theory with the PBE0 functional. The conformational dependence of the transition energies and other properties of free‐chain permethylatedn‐hexasilane,n‐Si6Me14, was also examined as a function of dihedral angles, and the striking effects found were attributed to avoided crossings between configurations of σσ* and σπ* character.