38870-72-3Relevant academic research and scientific papers
The kinetic behavior of planar nickel(II) complexes. I. Reaction with ethylenediaminetetraacetic acid
Murmann, R. Kent
, p. 116 - 124 (2008/10/08)
The kinetics of the reaction of EDTA with some planar, diamagnetic complexes of the type [Ni(AO)2-H]+ and [Ni(C-alkylen)2]+2 have been investigated spectrophotometrically in the pH range 6-12. The rates of ligand exchange were found to obey the expression: rate = k[complex]T + k′[EDTA]T[complex]T at constant pH and ionic strength. The N-alkylAO complexes and those of EnAO were approximately 200 times more stable kinetically than the parent complex. Steric hindrance accounts for the former slow rate while increased thermodynamic stability of the hydrogen bond accounts for the latter. The pH dependence of the rates is discussed in relation to the charge on the complex, which is related to the hydrogen-bond equilibrium constants, and with respect to association with EDTA-2 in the 5 and 6 co?rdination positions. Catalysis by other chelating ligands has been shown and an explanation discussed involving a five-co?rdinate activated state.
