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4181244 
Journal Article 
alpha-Substituent effects on Si-H, P-H and S-H bond dissociation energies 
Fu, Y; Yu, TQ; Wang, YM; Liu, L; Guo, QX 
2006 
Yes 
Chinese Journal of Chemistry
ISSN: 1001-604X 
24 
3 
299-306 
WOS:000235990900002 
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. 
substituent effect; bond dissociation energy; silyl radical; phosphorous radical; thiyl radical