Title: complex mechanism
Long Title: IUPAC Gold Book - complex mechanism
DOI: 10.1351/goldbook.C01205
Status: current

Definition
This term is sometimes applied to an elementary reaction which proceeds via an intermediate species having a lifetime longer than a few rotational periods, in contrast to a direct reaction. However, in view of the danger of confusion with a reaction occurring in more than one step (a composite reaction) this usage is not to be recommended; it is better to use the terms complex-mode mechanism or complex-mode reaction.

Related Terms
- complex-mode reaction: https://goldbook.iupac.org//terms/view/C01206
- composite reaction: https://goldbook.iupac.org//terms/view/C01211
- direct reaction: https://goldbook.iupac.org//terms/view/D01773
- elementary reaction: https://goldbook.iupac.org//terms/view/E02035
- mode: https://goldbook.iupac.org//terms/view/M03958

Source
- PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 160 (https://doi.org/10.1351/pac199668010149)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/C01205/html
- json: https://goldbook.iupac.org/terms/view/C01205/json
- xml: https://goldbook.iupac.org/terms/view/C01205/xml

Citation: Citation: 'complex mechanism' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.C01205
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Accessed: 2026-04-28T18:03:37+00:00