activated state

https://doi.org/10.1351/goldbook.08141
In theories of unimolecular reactions an energized chemical species, often characterized by the superscript ‡, where the excitation is specific and the molecule is poised for reaction.
Notes:
  1. Often used as a synonym for activated complex or transition state, but not restricted to transition-state theory.
  2. This is distinct from an energized molecule, often characterized by the superscript ∗, in which excitation energy is dispersed among internal degrees of freedom.
  3. This is not a complex according to the definition in this Glossary.
Source:
PAC, 2022, 94, 353. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)) on page 357 [Terms] [Paper]
Citation: 'activated state' 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.08141 RIS BibTex EndNote
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