Acid dissociation constants (pka) of the compounds involved is necessary in understanding the formation of metal complexes. This can also lead to assumptions whether a complexation reaction is likely or not to proceed. Knowing the value of the pka for the ligand is very helpful in solving the reaction of metal complexes with the ligand thus will be able to determine its stability in the solution.
Consider the general reaction:
`[M(H2O)n]^(m+) + LH -> [M(H2O)n-1]^(m-1) + H3O^(+)`
The knowing the pka of LH to produce H+ to protonate one H2O attached in the metal ion is useful to determine the equilibrium expression of the reaction mechanism.