alpha-Substituent effects on Si-H, P-H and S-H bond dissociation energies

作者：Fu Y^*; Yu TQ; Wang YM; Liu L; Guo QX

来源：Chinese Journal of Chemistry, 2006, 24(3): 299-306.

DOI：10.1002/cjoc.200690057

• substituent effect
• bond dissociation energy
• silyl radical
• phosphorous radical
• thiyl radical

CBS-Q and G3 methods were used to generate a large number of reliable Si-H, P-H and S-H bond dissociation energies (BDEs) for the first time. It was found that the Si-H BDE displayed dramatically different substituent effects compared with the C-H BDE. On the other hand, the P-H and S-H BDE exhibited patterns of substituent effects similar to those of the N-H and O-H BDE. Further analysis indicated that increasing the positive charge on Si of XSiH3 would strengthen the Si-H bond whereas increasing the positive charge on P and S of XPH2 and XSH would weaken the P-H and S-H bonds. Meanwhile, increasing the positive charge on Si of XSiH2 center dot stabilized the silyl radical whereas increasing the positive charge on P and S in XPH center dot and XS center dot destabilized P- and S-centered radicals. These behaviors could be reasonalized by the fact that Si is less electronegative than H while P and S are not. Finally, it was demonstrated that the spin-delocalization effect was valid for the Si-, P- and S-centered radicals.

• 出版日期2006-3
• 单位中国科学技术大学