二甲基硅硼烷,o-(SiMe)_2B_(10)H_(10),振动光谱的理论研究

本文利用高斯 94从头计算程序在 6- 31 G基组下对二甲基硅硼烷 ,o- (Si Me) 2 B1 0 H1 0 ,进行几何优化及振动光谱的理论计算 ,并对主要谱带特性进行指认 ,结果与实验基本符合。振动模式分析表明 450 cm-1 以下的两个强带中 32 6cm-1 (计算值为 369cm-1 )似乎是两个 Si原子相对笼骨架中其余 B原子整体的伸缩振动 ,而 399cm-1 (计算值为 42 1 cm-1 )则为 Si- Si(及其联带的 C原子一起参与的 )对称伸缩振动。优化几何及振动光谱的研究表明重的杂原子硅占据二十面体硼笼骨架位置后使笼结构的刚性弱化

A Theoretical Study on the Vibrational Spectra of 1,2-Dimethy-o-silaborane o- (SiMe)2B10H10

Geometrical optimization and theoretical calculation of the vibrational spectra of 1,2 dimethy o silaborane, o (SiMe) 2B 10 H 10 were performed using the 6 31G basis sets of the Gaussian94 program. The results are in good agreement with the experimental values. The assignments of several important spectral bands are made on the basis of this analysis. In the region below 450 cm -1 , two intense Raman bands appear at 326 cm -1 and 399 cm -1 , which compare well with the calculated frequencies of 369 cm -1 and 421 cm -1 respectively. Thus, the former mode can be attributed to the stretching of the two silicon atoms in the cage frame with respect to the rest of the molecule. The latter mode can be assigned to the stretching between the two silicon atoms themselves. The current study also reveals that substituting the icosahedral carborane CH groups by heavier hetero atoms such as Si leads to a weakening of the rigidity of the cage structure.