Abstract:

Kinetic studies on the electron transfer(ET) reaction of [Co(NH3)5(ImH)]3+/[Fe(CN)6]4- and trans-[Co(NH3)(en)2(ImH)]3+/[Fe(CN)6]4- have been carried out at various temperatures. The results indicated that these two ET reactions followed the outer sphere mechanism. At 25℃,I=0.50mol L-1, the ion pair formation constants Qip of the precursor complexes in the ET reactions are 2.6×102 and 4.9 × 102mol L-1 ,and the electron transfer rate constants kct are 2.1 ×10-4 and 5.2 ×10-5s-1 respectively. The activation enthalpy △Het≠ and the activation entropy △Set≠ of these two processes are 1.2×102, 0.8×102kJ/mol and 5.1×102, 3.6×102kJ/mol﹒K-1 respectively.

Key words: Electron transfer reaction, Outer sphere mechanism, Imidazole complex, Co(III) complex