Rate constants for the base hydrolysis of bis(naphthylidene alanate)iron (II) (nali), bis (naphthylidene phenylalanate)iron(II) (nphali), bis(naphthylidene aspartate)iron(II) (nasi) (naphthylidene histidinate)iron(II) (nhi), bis(naphthylidene arginate)iron(II) (nari) have been reported in different binary aqueous solvent mixtures at 298 K. The observed reactivity trends are discussed in terms of the hydrophilic and hydrophobic forms of the complexes investigated,
as well as the transfer chemical potentials of the hydroxide ion and the complex. Both the solvent–
solute and solvent–solvent interactions have been considered. The hydrophobic character of the complexes studied was manifested by a decrease in reactivity. Solvent effect on reactivity trends of the investigated complexes have been analyzed into initial and transition state components. This can be achieved by using the transfer chemical potentials of the reactants and the kinetic data of the studied compounds. The decrease in the observed rate constant values (kobs) of the base hydrolysis of the investigated complexes with increase of solvent% is dominated by the initial state (IS).