Term: formation constant
https://doi.org/10.1351/goldbook.F02485

Definition:
For a mononuclear binary complex, if a central atom (central group) M (the 'metal') and a ligand L have been defined, then in the following expressions Kn is the stepwise formation constant, and β n is the cumulative formation constant for the complex MLn. They can both be referred to as stability constants (stepwise and cumulative). \[K_{n}=K(\text{ML}_{n- 1}+\text{L}\rightleftharpoons \text{ML}_{n})\] \[\beta_{n} = K(\text{M}+n\text{L}\rightleftharpoons \text{ML}_{n})\]

Related Terms:
1) central atom (http://doi.org/10.1351/goldbook.C00930).

Source: Orange Book, 2nd ed., p. 11 (https://media.iupac.org/publications/analytical_compendium/)

Citation: 'formation constant' 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.F02485

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