Kinetics of the reduction of di- - oxo–tetrakis (1,10-phenan- throline)-dimanganese (III, IV) perchlorate by thiosulphate ions in acid medium

Abstract

The kinetics of reduction of di-µ- oxo –tetrakis (1,10-phenanthroline) – dimanganese (III, IV) perchlorate (Mn^IIIO₂Mn^IV) by thiosulphate ions in acid medium has been investigated. The reduction is first order in both oxidant and reductant. The reaction obeys the rate expression 
Where a =7.01 x 10^-3 mol dm^-3s^-1   b = 0.92 x 10^-3 mol dm^-3 s^-1 at 28.0 +1⁰C, [H+] =2x10^-3mol dm^-3 and max
 = 580nm. The rate of reduction increased with increase in ionic strength and dielectric constant. It is unaffected by
 cationic and anionic species. There is no evidence for the formation of an intermediate complex of
 significant stability. Free radicals were found to be present in this reaction. The results obtained support
 the proton coupled electron transfer (PCET) pathway and is hereby proposed for the reaction.