咪唑钴(III)配合物还原动力学机理研究

配合物间的电子转移反应是近代化学中重要的一类反应［‘，’J，对于大多数反应来说，由于前驱配合物离子对形成常数较小，难以独立分离出各基元步骤动力学参数问；给研究带来困难问．为了丰富电子转移反应研究内容，寻找更多可供详细研究的反应体系，在前文报导［Fe（CN）6p还原高位阻［Co（tmen）3p”的反应动力学研究基础上＊，本文进一步合成了含有生物体系中常见配体咪哩（IInll）的Co仰）配合物［Co（NH。）。（ImH）］（CIO小和t，an。－［Co（NH。）（en）。（IInH）］（C104）。，再以［Fe（CN）6p为还原剂，考察了两C…

Kinetic Investigation on the Mechanism of the Reduction of Imidazole Cobalt(III) Complexes

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.