Kinetic studies on the periodate oxidation of an iron(II) oxime-imine complex

The iron(II) complex of H2L (H2L = 3, 14-dimethyl-4, 7, 10, 13-tetraazahexa deca-3,13-diene-2,15-dione dioxime, Coord. Chem. Rev., 33, 87 (1980)) is ox idized by periodate very rapidly in the range pH 2.0-7.0, and the kinetics of the reaction has been followed by stopped-flow spectrophotometry at 30 d egrees C and ionic strength I = 0.20 mol L-1 (NaClO4). The reaction is Foun d to follow a simple second-order kinetics as - d/dt[Fe-II(H2L)(2+)] = k [F e-II(H2L)(2+)] [I(VII)], giving [Fe-III(L)](+) and IO3- as the final produc ts. The reaction has been proposed to occur through a H-bonded transition s tate Formed probably between the protonated oxime group of the ligand and t he oxygen atom on the periodate species, followed by an electron transfer F rom Fe-II centre to I-VII in a rate-determining step. The I-VI species thus generated reacts in a fast step with another Fe-II complex. (C) 1999 John Wiley & Sons, Inc.