Hyperconjugation with a Bonds

In principle a crx A — 0 Y-A charge-transfer interaction would also be possible when the two vicinal X-A and Y-A bonds adopt a synperiplanar conformation. However, in this latter conformation the overlap integral crx A — j Y A and thus the 

Side Reactions in Organic Synthesis. Florencio Zaragoza Dorwald Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31021-5 

Hyperconjugation between sp3 hybridized atoms can have important implications for the ground-state conformation of organic compounds. It has, for example, been suggested that the energy difference between the staggered and the eclipsed conformations of ethane is due to both hyperconjugation and repulsion [2-5]. The fact that 

2- difluoroethane. Because the C-F bond is a poorer electron donor than the C-H bond, the gauche conformation, which enables two crC-H — 7 c-f interactions, is approximately 0.7 kcal/mol more stable than the anti conformation. 

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K Relaxation mechanism was also proposed [130-133], The % relaxation originates from cyclic delocalization of % electrons in the double bond through the hyperconjugation with a bonds on the saturated ring atoms under control of the orbital phase property [134, 135],... 

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