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Kinetics and equilibrium study of nickel(II) complexation by pterin
Author(s) -
Monópoli Víctor D.,
Thomas Andrés H.,
Capparelli Alberto L.
Publication year - 2000
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/(sici)1097-4601(2000)32:4<231::aid-kin5>3.0.co;2-y
Subject(s) - chemistry , pterin , ionic strength , equilibrium constant , nickel , kinetics , reaction rate constant , stoichiometry , aqueous solution , metal , metal ions in aqueous solution , ligand (biochemistry) , stability constants of complexes , inorganic chemistry , organic chemistry , physics , cofactor , quantum mechanics , enzyme , biochemistry , receptor
The kinetics of complexation of Ni(II) by pterin was studied in aqueous solutions with a stopped‐flow apparatus under conditions of pseudo‐first order in the temperature range 5–45°C, pH between 4.0 and 6.5, and ionic strength 0.4 M. The equilibrium constants, stoichiometry, and pK a of the ligand and complex were also determined using a spectrophotometric technique. The results are consistent with the formation of a 1:1 complex between the metal ion and pterin. The first‐order experimental rate constant k app is pH independent and shows the following dependence with the ion metal concentration at 25°C: k app /s −1 = 3.8 × 10 −3 + 1.6 × 10 −4 × [Ni(II)] −1 . A global activation energy of 57 ± 2 kJ/mol associated with the formation of a 1:1 chelate was measured. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 231–237, 2000