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The kinetics of complexation of nickel(II) and cobalt(II) with cinchomeronate in aqueous solution
Author(s) -
Yun Sock Sung,
Choi Ki Young
Publication year - 1989
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.550211206
Subject(s) - chemistry , cobalt , nickel , aqueous solution , reaction rate constant , ionic strength , dissociation (chemistry) , pyridine , chelation , inorganic chemistry , kinetics , ion , medicinal chemistry , organic chemistry , physics , quantum mechanics
The pressure‐jump method has been used to determine the rate constants for the formation and dissociation of nickel(II) and cobalt(II) complexes with cinchomeronate in aqueous solution at zero ionic strength. The forward and reverse rate constants obtained are k f = 2.27 × 10 6 M −1 s −1 and k r = 3.81 × 10 1 s −1 for the nickel(II) complex and k f = 1.23 × 10 7 M −1 s −1 and k r = 2.66 × 10 2 s −1 for the cobalt(II) complex at 25°C. The activation parameters of the reactions have also been obtained from the temperature variation study. The results indicate that the rate determining step of the reaction is a loss of a water molecule from the inner coordination sphere of the cation for the nickel(II) complex and the chelate ring closure for the cobalt(II) complex. The influence of the pyridine ring nitrogen atom of the cinchomeronate ligand on the complexation of cobalt(II) ion is also discussed.