Ligand effects on the kinetics of the reversible binding of NO to selected aminocarboxylato complexes of iron(II) in aqueous solution

Abstract

Rate constants for the formation and dissociation of FeII(L)NO (L = aminocarboxylato) have been determined using stopped-flow, temperature jump, flash photolysis, and pulse radiolysis techniques. For a series of ligands the formation rate constants vary between 1.6 × 106 and 2.4 × 108M−1 s−1, whereas the dissociation rate constants vary between 0.11 and 3.2 × 103 s−1 at 25 °C. These rate constants result in stability constants (KNO = kf/kd) ranging from 5.0 × 102 to 1.1 × 107M−1, which are in good agreement with values of KNO determined by a combined spectrophotometric and potentiometric technique. The results are discussed with reference to available literature data, and interpreted in terms of a generalized reaction mechanism