Kinetic study of Nickel(II) complexation by pteroylglutamic acid

ANDRÉS H. THOMAS; EZEQUIEL WOLCAN; MARIO R. FÉLIZ; ALBERTO L. CAPPARELLI

TRANSITION METAL CHEMISTRY

Springer

Año: 1997 vol. 22 p. 541 - 544

0340-4285

The kinetics of the complexation of NiII by pteroylglutamic acid was studied in 5 - 45 oC range, the ionic strength (0,6 M) being regulated with KNO3, in the 5.5 - 7.0 pH range, and using the stopped flow method. Under the experimental conditions two processes were observed. The faster process was detected in the millisecond time range and is associated with the reaction between NiII and the ligand. The slower is observed within a few seconds. Complementary equilibrium studies were made at 25 oC. The results are consistent with the formation of a 1:1 complex between the reactants, and a mechanism is proposed to account for the observed behaviour. Equilibrium constants for the NiII plus pteroylglutamic acid system, as well as activation parameters, are reported.