Rate enhancements in the four-electron reduction of O2 by mixtures of vanadium(III) Schiff base complexes and decamethylferrocene in acetonitrile
作者:Zenghe Liu、Fred C Anson
DOI:10.1016/s1381-1169(02)00184-x
日期:2002.7
The otherwise slow reaction between O-2 and decamethylferrocene (DMFc) or (SB)VIII+ (SB = Schiff base ligand) is significantly accelerated if all three reactants are present. In the absence of acid the reduction of O-2 proceeds stoichiometrically to yield the two oxo groups in (SB)(VO)-O-IV. In the presence of acid the reaction becomes catalytic and the O-2 is reduced to H2O. In the presence of excess O-2 the catalytic reaction ceases only when the supply of DMFc or acid is depleted. Investigation of the kinetics of the O-2 reduction processes led to a reaction scheme that accounts for much but not all of the kinetic data. (C) 2002 Elsevier Science B.V. All rights reserved.
Influence of the nature of the metal ion on the rate of reduction of coordinated azomethine group
作者:A. A. Medzhidov、S. G. Mamedova、A. Aydin、B. Yalcin、S. Tascioglu、E. Kaki
DOI:10.1134/s1070363207100155
日期:2007.10
The kinetics of reduction of the azomethine bond in various Schiff bases and their transition metal complexes with sodium borohydride in dimethylformamide and ethanol solutions was studied. The reduction rate depends on both the structure of the starting Schiff bases and the nature of the metal ion. In transition metal N-phenylsalicylaldiminates, the rate of reduction of the azomethine group increases in the order Zn(II) < Ni(II) < Cu(II) < Co(II) < VO(II) < Mn(II). Similar trend is observed in other series of metal complexes with Schiff bases. The revealed trends are opposite to the Irving-Williams series of stability of complexes. This fact suggests that the major factor affecting the rate of reduction of the coordinated azomethine bond is the strength of its bonding with the metal ion. Depending on particular metal ion, the complexation can either decelerate or accelerate the reduction.