16091-77-3Relevant academic research and scientific papers
Kinetics of Reduction of Tris(ethylenediamine)cobalt(III) by Ethylenediamine-NNN'N'-tetra-acetochromate(II)
Segal, Michael G.
, p. 2485 - 2488 (2007/10/02)
The kinetics of the reduction of 3+ (en=ethylenediamine) by 2- have been studied by stopped-flow methods under a variety of conditions.The reaction is first order in both reagents, with a second-order rate constant of 3.37*103 dm3 mol-1 s-1 at 25 deg C, pH 4.81, unit ionic strength and =5*10-2 mol dm-3 (edta=ethylenediamine-NNN'N'-tetra-acetate).Activation parameters (ΔH=56 kJ mol-1, ΔS=12 J K1- mol-1) are consistent with weak electrostatic attraction between the reactants.The rate shows an inverse dependence on the concentration of free edta, attributed to formation of an ion pair or hydrogen-bonded adduct with the oxidant.The pH dependence is a double sigmoid, consistent with two protonation equilibria in the reductant with pKa values 2.7 and 5.5, and the reaction rate increases with increasing numbers of negative donor groups in the complex.
KINETICS OF THE REDUCTION OF (ETHYLENEDIAMINETETRA-ACETATO)COBALTATE(III) AND RELATED COMPLEXES BY CHROMIUM (II) IONS
Ogino, Hiroshi,Kikkawa, Etsuko,Shimura, Makoto,Tanaka, Nobuyuki
, p. 894 - 896 (2007/10/02)
Rate constants of the electon-transfer reactions of three cobalt(III)-edta (edta = ethylenediaminetetra-acetate) complexes with Cr2+ have been determined by a stopped-flow spectrophotometric method at 25 deg C and ionic strength of 1.0 mol dm-3 (Na).The values are (6.6 +- 1.0) x 103 dm3 mol -1 s-1 for -, (7.6 +- 0.4) x 103 dm3 mol-1 s-1 for , and >2 x 106 dm3 mol-1 s-1 for -.A comparison with other reducing agents 2+, 4-, and TiIII> indicates that titanium(III) reduction of the same series of cobalt(III)-edta complexes studied by Marcec and Orhanovic proceeds via outer-sphere mechanism.
