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Concerning the Electronic Control of Torsion Angles in Biphenyls
Author(s) -
GómezGallego Mar,
MartínOrtiz Mamen,
Sierra Miguel A.
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100874
Subject(s) - steric effects , chemistry , torsion (gastropod) , acceptor , electronic effect , chemical mechanical planarization , gas phase , computational chemistry , stereochemistry , crystallography , organic chemistry , condensed matter physics , medicine , physics , surgery , layer (electronics)
Abstract In the search for evidence to establish the effect of π conjugation on the variation of the equilibrium torsion angle ( θ eq ) in push–pull 4,4′‐disubstituted biphenyls, a systematic Hammett DFT study has been carried out. The study shows that although reasonable and intuitive, the through‐conjugation between donor and acceptor substituents in these systems is only of some relevance when strong donor and strong charged acceptors are involved. In these cases, changes in the torsion angle from 39 (average) to 10.2° have been observed in the gas phase. Otherwise, θ eq is mainly dominated by the (steric) ortho – ortho effect. The results of this study, based on the electronic control of the torsion angle, are complementary to those that rely on planarization by means of reduction of the steric constriction at the 2,2′‐positions of the system.