https://doi.org/10.1351/goldbook.Q04999
In conventional @[email protected] it is assumed that @[email protected] are formed in a state of equilibrium with the reactants. They are not in classical equilibrium with the reactants; if they were, addition of more activated complexes to the system would cause the equilibrium to shift in favour of the reactants. This would not occur for an @[email protected], and the term quasi-equilibrium is used to denote this special type of equilibrium.