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Kinetics and mechanism of ligand substitution in binuclear nickel(II) and cobalt(II) complexes
Author(s) -
Hynes Michael J.,
Doody Marie T.
Publication year - 1995
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550270502
Subject(s) - nitrilotriacetic acid , chemistry , ionic strength , cobalt , kinetics , ligand (biochemistry) , nickel , medicinal chemistry , reaction rate constant , inorganic chemistry , divalent , reactivity (psychology) , associative substitution , chelation , stereochemistry , catalysis , organic chemistry , biochemistry , physics , receptor , quantum mechanics , aqueous solution , medicine , alternative medicine , pathology
The kinetics and mechanism of the removal of M 2+ from bis ‐(heptane‐2,4,6‐trionato)M(II) [M = Ni, Co] by ethylenediminetetraacetic acid (EDTA), nitrilotriacetic acid (NAT), 1,2‐cyclohexanediamine‐ N , N , N ′, N ′‐tetraacetic acid (C y DTA), and ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) have been investigated using stopped‐flow spectrophotometry in methanol‐water at 25°C and ionic strength 0.1 mol dm −3 KNO 3 . The reactions were investigated at a number of different pHs. An associative mechanism is proposed to account for the kinetic data. Although all the ligands have similar functional groups, their reactivity towards the parent complex is quite different. The pH dependence of the rate constants has been used to determine the relative reactivities of the various ligand species present. In the case of nitrilotriacetic acid, a nonlinear dependence on ligand concentration is observed, thus confirming the mechanism proposed. © 1995 John Wiley & Sons, Inc.