Chemical polarity due to interactions between pi bonds or lone pairs
See also: Resonance (chemistry)
In chemistry, the mesomeric effect (or resonance effect) is a property of substituents or functional groups in a chemical compound. It is defined as the polarity produced in the molecule by the interaction of two pi bonds or between a pi bond and lone pair of electrons present on an adjacent atom.[1] This change in electron arrangement results in the formation of resonance structures that hybridize into the molecule's true structure. The pi electrons then move away from or toward a particular substituent group. The mesomeric effect is stronger in compounds with a lower ionization potential. This is because the electron transfer states will have lower energies.
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In chemistry, the mesomericeffect (or resonance effect) is a property of substituents or functional groups in a chemical compound. It is defined as the...
effect is no longer used in standard texts and is considered as obsolete. The concepts implied by the terms electromeric effect and mesomericeffect are...
ionization constant. It is distinct from and often opposite to the mesomericeffect. Covalent bonds can be polarized depending on the relative electronegativity...
deactivating effect, the resonance (or mesomeric) effect is almost always stronger, with the exception of Cl, Br, and I. In general, the resonance effect of elements...
inductive effect (-I) and also by a negative mesomericeffect (-M). The next set of substituents are the halogens, for which the substituent effect is still...
interact, the stereoelectronic effect, along with the steric effect, inductive effect, solvent effect, mesomericeffect, and aromaticity, is an important...
isomers. Substituents can be a combination of the inductive effect and the mesomericeffect. Such effects are also described as electron-rich and electron...
aromatic ring system, the nitrogen atom cannot exhibit a positive mesomericeffect. Many analogues of pyridine are known where N is replaced by other...
to unsaturated groups results in significant stabilization by the mesomericeffect (resonance), the benefit is partially offset by the presence of a more...
proposal in the new field of molecular electronics (UE). Based on the mesomericeffect of certain chemical compounds on organic molecules, a molecular rectifier...
and mesoionic compounds cannot be represented satisfactorily by any one mesomeric structure. Mesoionic compounds are a subclass of betaines. Examples are...
Teresa J.; Breneman, Curt M.; Frisch, Michael J. (1992). "Analysis of the effect of electron correlation on charge density distributions". The Journal of...
October 2004). "Alfred Werner's Inorganic Counterparts of Racemic and Mesomeric Tartaric Acid: A Milestone Revisited". Inorganic Chemistry. 43 (20): 6249–6254...
be dangerous by causing cold burns on contact, although the Leidenfrost effect provides protection for very short exposure (about one second). Ingestion...
pKa near 8. Inductive effects and mesomeric effects affect the pKa values. A simple example is provided by the effect of replacing the hydrogen atoms in...
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