The influence of lone-pair repulsions on C–C bond lengths: a critical evaluation of the experimental and theoretical evidence

Rathna, Ananthaiah and Chandrasekhar, Jayaraman (1991) The influence of lone-pair repulsions on C–C bond lengths: a critical evaluation of the experimental and theoretical evidence. In: Perkin Transactions 2 (11). pp. 1661-1666.

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Abstract

X-Ray structural data, as well as semiempirical and ab initio molecular orbital calculations, reveal no systematic and substantial difference between the C–C bond lengths of cis and trans 1,2-diketones. Additional results on various conformations of 1,2-diimines and 1,2-dithiones follow the same pattern. Therefore, lone-pair repulsions cannot be implicated in the observed lengthening of C–C bonds in isatin and several related molecules. Conjugation in these systems occurs peripherally avoiding the participation of the central C–C bond. Negative hyperconjugative interaction between the oxygen lone pairs and the adjacent C–C σ* orbital is suggested to be the principal reason for the relatively long C–C bond in diketones. This effect is found in both the cis and trans conformations.

Item Type:	Journal Article
Publication:	Perkin Transactions 2
Publisher:	Royal Society of Chemistry
Additional Information:	Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	07 Dec 2010 07:38
Last Modified:	07 Dec 2010 07:38
URI:	http://eprints.iisc.ac.in/id/eprint/34240

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