The kinetic properties of the complexes formed in aqueous solutions of the Fe2+-glycinate (glyO), -ethylenediamine (en) and -malonate (mal) systems have been investigated by measuring the paramagnetic relaxation rate and shift of the CH2 protons of the ligands over a wide range of complex formation. The formation rate constants (kf) of the parent complexes are as follows: glycinate, k1 = 5.4 × 106, k2 = 5.0 × 106, and k3 = 1.9 × 106; ethylenediamine, k1 = 7.1 × 107, k2 = 1.8 × 107, and k3 = 2.1 × 106; malonate, k1 = 6.8 × 107 and k2 = 1.3 × 107 dm3 mol-1 s-1. Kinetic evidence for the formation of [Fe(gly)]2+, [Fe(Hen)]3+, and [Fe(Hmal)]+ complexes is provided. A 'carboxyl-displacement' mechanism is suggested for the interaction between [Fe(glyO)3]- and free glyO- ligand.
|Number of pages||5|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - Dec 1 1990|
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