The degree/level of association among the species involved in a state of equilibrium determines the stability of a coordination molecule in a solution.
The formation constant or stability constant can be used to express stability numerically.
M + 3L ⇔ ML3
Stability constant , β = [ML3]/[M] [L]3
The greater the value of β, the stronger is the metal-ligand bond.
Charge on the central metal ion – the higher the charge, the more stable the complex.
( 1 ) Charge on the central metal ion – the higher the charge, the more stable the complex.
( 2 ) Ligand nature – chelating ligands result in a more stable compound.
( 3 ) The ligand’s basic strength—the more basic a ligand is, the more stable its complex is.