Wang, Youliang and Poirier, Raymond A. (1998) Generalized valence bond study of rotational singlet structures and π bond energies for systems containing C=C, Si=Si, and C=Si double bonds. Canadian Journal of Chemistry, 76 (4). pp. 477-482. ISSN 0008-4042 http://resolver.caltech.edu/CaltechAUTHORS:20120119-071022174
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Ab initio GVB(6/12)/6-31G^(**) calculations were performed on A_2X=YB_2 (A, B = H, F; X, Y = C, Si) to obtain the optimized geometries for planar and twisted singlet structures, and to also calculate π bond energies (rotational barriers). The nature of C-C, Si-Si, and C-Si π bonds has been investigated. The results show that the C-C π bond energy (E_π (ethene) = 65.4 kcal/mol) decreases with increasing fluorine substitution. The pyramidalization at the carbon or silicon center for the twisted structures decreases the π bond energies in the substituted ethenes and their silicon counterparts. The Si-Si (E_π (disilene) = 23.2 kcal/mol) and C-Si (E_π (silaethene) = 31.6 kcal/mol) π bonds become much weaker. Fluorine substitution stabilizes both the diradical and the dipolar twisted singlet structures.
|Additional Information:||© 1998 NRC Canada. Received September 29, 1997. The continuing financial support (to R.A.P.) of the Natural Sciences and Engineering Research Council of Canada (NSERC) is gratefully acknowledged. The authors would like to thank Mr. James Xidos for reading the manuscript.|
|Subject Keywords:||π bond energy, ab initio calculations, generalized valence bond, fluorine substitution, disilene, and silaethene.|
|Official Citation:||Generalized valence bond study of rotational singlet structures and pi bond energies for systems containing C==C, Si==Si, and C==Si double bonds Youliang Wang, Raymond A Poirier Canadian Journal of Chemistry, 1998, 76:(4) 477-482, 10.1139/v98-041|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||19 Jan 2012 15:45|
|Last Modified:||19 Jan 2012 18:11|
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