A molecular
polarizability effect occurring by an
intramolecular electron displacement (sometimes called the '
conjugative mechanism' and, previously, the '
tautomeric mechanism') characterized by the substitution of one electron pair for another within the same
atomic octet of electrons. It can be indicated by curved arrows symbolizing the displacement
of electron pairs, as in:
which represents the hypothetical electron shift
The term has been deemed obsolescent or even obsolete (see
mesomeric effect,
resonance effect). It has long been custom to use phrases such as '
enhanced substituent resonance effect' which imply the operation of the electromeric effect, without using the term, and
various modern theoretical treatments parametrize the response of substituents to
'
electronic demand', which amounts to considering the electromeric effect together with the
inductomeric effect.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1109
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
