Term: nonbonding molecular orbital
https://doi.org/10.1351/goldbook.NT07083

Definition:
A molecular orbital whose occupation by electrons does not contribute (or contributes insignificantly) to the binding energy of the molecule. Generally, a nonbonding MO represents the highest occupied molecular orbital of a molecule.

Related Terms:
1) molecular orbital (http://doi.org/10.1351/goldbook.M03996).
2) binding energy (http://doi.org/10.1351/goldbook.BT07001).

Source: PAC, 1999, 71, 1919. 'Glossary of terms used in theoretical organic chemistry' on page 1955 (https://doi.org/10.1351/pac199971101919)

Citation: 'nonbonding molecular orbital' 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.NT07083

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