delocalization of electrons

https://doi.org/10.1351/goldbook.08789
Redistribution of electron density in a molecular entity as compared with a model assuming individual atoms in the same valence states connected by localized bonds.
Notes:
  1. Topological modes of the electron delocalization include:
    1. ribbon (one-dimensional) delocalization of π- or σ-electrons or both, which is typical of linear conjugated polymers that are therefore termed one-dimensional conductors;
    2. surface delocalization of π- or σ-electrons or both through an overlap of radially oriented orbitals of a cyclic molecule such as a molecule of cyclopropane or benzene;
    3. volume delocalization of σ-electrons through an overlap of σ-orbitals directed inside a molecular polyhedron, e.g., in tetrahedrane or carboranes.
  2. A delocalized electron is not associated with a particular atom or particular covalent bond but occupies an extended orbital spread over several to many atoms or the whole lattice.
  3. Extensive delocalization of electrons is typical of metals, semiconductors, graphite, conjugated polymers, polysilanes, boranes, conjugated compounds such as organic dyes and others.
See also: extent of electron delocalization, molecular orbital theory
Source:
PAC, 2022, 94, 15. (Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)) on page 22 [Terms] [Paper]
Citation: 'delocalization of electrons' 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.08789 RIS BibTex EndNote
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