π-electron acceptor/donor group

https://doi.org/10.1351/goldbook.E04391
A substituent capable of a $\ce{+R}$ (e.g.$\ce{NO2}$) or $\ce{-R}$ (e.g. $\ce{OCH3}$) effect, respectively.
See: σ-constant, polar effect, electronic effect
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1155 [Terms] [Paper]
Citation: 'π-electron acceptor/donor group' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.E04391 RIS BibTex EndNote
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