Kinetics and outer sphere electron transfer of some metallosurfactants by Fe(CN)6 4− in microheterogenous medium: a detailed thermodynamic approach

Abstract

Abstract We report the rate of electron transfer reaction of complexes, cis-[M(ED)2(DOD)2]3+ (1), cis-[M(DP)2(DOD)2]3+ (2), cis-[M(TRE)(DOD)2]3+ (3), cis-[M(bpy)2(DOD)2]3+ (4) and cis-[M(PA)2(DOD)2]3+ (5) (M:Co, ED: ethylenediamine, TRE: triethylenetetramine, DP: diaminopropane, PA: phenanthroline, C12H25NH2: dodecylamine (DOD) and bpy: bipyridine) and hexacyanoferrate ion in surface active ionic liquids (BMIM)Br were studied at 298–323 K by electronic absorption spectroscopy. Surfactant complexes 4 and 5, which have a higher ETR than complexes 1–3 based on the results obtained, have been explained based on the states of aggregation and hydrophobic transformations between the hydrocarbon portion of the surfactant compounds and (BMIM)Br. As a result, surface-active agent micelles in (BMIM)Br and increase ETR in between the system. The investigation of kinetic statistics outcomes suggest that reduction reaction between surface-active agent Co(III) complexes and hexacyanoferrate occurs via 2nd order and the ET is proposed as outer sphere. The remarkable increase in the rate for the ETR in (BMIM)Br with increase in the concentration of Co(III) complexes from 1–5. This can be attributing due to the fact those reactants with opposite charges and the amphipilicity of the ligand. The OSET of kinetics have been confirmed by the enthalpy and entropy (ΔS # and ΔH #) factors, and the isokinetic plots (ΔS # versus ΔH #) have shown that the reaction’s mechanism does not alter during the (BMIM)Br medium.