75456-03-0Relevant academic research and scientific papers
Mechanism of electron transfer to pentaammine(pyridine)cobalt(III) complexes by aliphatic radicals, hexaaquovanadium(II), and hexaamimneruthenium(II) ions
Bakac, Andreja,Butkovi?, Vjera,Espenson, James H.,Marcec, Radovan,Orhanovi?, Matko
, p. 341 - 345 (2008/10/08)
The rates of electron transfer to a series of pentaammine(pyridine)cobalt(III) complexes, Co(NH3)5(NC5H4X)3+ (X = 3-CN, 3-Cl, H, 4-CH3, 4-C(CH3)3, and 4-N(CH3)2), have been determined. A kinetic competition method based on the homolytic scission of the chromium-carbon bond in (H2O)5CrC(CH3)2OH2+ was used to evaluate rate constants for the reducing agent ·C(CH3)2OH, whereas direct measurements were carried out for the reductions by V(H2O)62+ and Ru(NH3)62+. In all three cases the rate constants show mild and similar sensitivity to the substituent on the pyridine ring. The variations are well correlated by the Hammett equation, the reaction constants being 1.1, 1.3, and 1.5, respectively. Arguments are advanced that in each case the reactions proceed by direct outer-sphere electron transfer to the cobalt(III) and not by a chemical mechanism entailing prior electron transfer to the pyridine ring.
