
TY  - JOUR
A1  - Williams, NH 
A1  - Yandell, JK 
T1  - Ruthenium and iron complexes of dipicolinic acid: Synthesis, solution properties and kinetics of electron transfer reactions with ascorbate ions
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1983
VL  - 36
IS  - 12
SP  - 2377
EP  - 2386
KW  - 
UR  - https://doi.org/10.1071/CH9832377 
N2  - Standard potentials of the redox couples [bis(pyridine-2,6-dicarboxylate)MIII]-/2- ([M(dipic)2]-/2-, where M = Fe, Ru, Co) have been determined at 25ºC, and ionic strength 0.1M (NaClO4 or KNO3). Kinetics of reduction of the oxidized complexes by ascorbate have also been examined under the same conditions. The [Fe(dipic)2]-/2- potential was found to be 355 ± 5 mV. Reduction of [Fe(Fe(dipic)2]- in the pH range 4-6 was shown to occur by reaction with ascorbate monoanion (HA-) with a rate constant of (2.2 ± 0.2) &#215; 103 1. mol-1 s-1, and ascorbate dianion(A2-) with a rate constant of (7 ± 1) &#215; 108 1. mol-1 s-1. K [Ru(dipic)2] has been synthesized. Spectroscopic and analytical evidence suggest that it is a simple six-coordinate species in the solid and in non-aqueous solvents, but that in water it exists as an equilibrium mixture of at least two species. The redox potential for this mixture was found to be 270 ± 10 mV. The major component of this mixture is reduced by A2- with a rate constant of (4.7 ± 0.1) &#215; 1081.mol-1 s-1. A value of 747 ± 5 mV was measured for the redox potential of the cobalt couple, although equilibration of this system with the inert electrode could be achieved only by using [Fe(bpy)2(CN)2] as a mediator. Kinetics of reduction of [Co(dipic)2]- by ascorbate were complex and not reproducible. 
ER  -

