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化学学报
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化学学报 ›› 1996, Vol. 54 ›› Issue (2): 167-174. 上一篇    下一篇

研究论文

trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)]^2^+/Fe(Ⅱ)间电子转移反应动力学及机理研究

颜文斌;周朝晖;章慧;俞鼎琼;徐志固   

  1. 湖南吉首大学化学系;厦门大学化学系
  • 发布日期:1996-02-15

Kinetic investigation of electron transfer reaction between trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)]^2^+/Fe(Ⅱ)

YAN WENBIN;ZHOU ZHAOHUI;ZHANG HUI;YU DINGQIONG;XU ZHIGU   

  • Published:1996-02-15

PDF

334

被引次数

7

合成了新型Co(Ⅲ)配合物trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)](ClO~4)~2, 并通过紫外可见光谱、红外光谱、元素分析和X射线单晶衍射分析进行了表征。同时分别以[Fe(CN)~6]^4^-和[Fe(CN)~5(H~2O)]^3^-作为还原剂, 考察了该配合物被还原的反应动力学行为。结果表明两反应体系分别按外配位界机理和内配位界机理进行电子传递。在25℃, Ⅰ=0.5mol·L^-^1,trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)]^2^+/[Fe(CN)~6]^4^-反应体系的前驱配合物离子对形成常数Q~i~p=29mol^-^1·L, 电子转移速率常数k~e~t=2.4×10^-^4s^-^1,电子转移过程的活化焓△H^≠~e~t和活化熵△S^≠~e~t分别为1.2×10^2kJ·mol^-^1和5.0×10^2J·mol^-^1·K^-^1。在40℃, pH=8.0, Ⅰ=0.1mol·L^-^1,trans-[(en)~2(NO~2)Co(O~2CC~5H~4N)]^2^+/[Fe(CN)~5(H~2O)]^3^-反应体系前驱双核配合物分子内电子转移速率常数为7.0×10^-^5s^-^1。最后讨论了分子轨道对称性, 两金属中心氧化还原电势差等因素对电子转移速率的影响。

关键词: 紫外分光光度法, 吡啶 P, 红外分光光度法, 反应动力学, 元素分析, 晶体结构, 钴络合物, 电子转移反应, 衍射分析, 内配位界机理

trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)]^2^+(ClO~4)~2, which is first reported, has been synthesized and characterized by elemental analysis, UV-Vis and IR spectra, and X-ray structural analyses. Kinetic behaviours of the Co(Ⅲ) complex reduced by [Fe(CN)~6]^4^- and [Fe(CN)~5(H~2O)]^3^- have been investigated. The results indicated the electron transfer (ET) reactions followed the outer-sphere mechanism or the linner-sphere mechanism respectively. At 25℃, Ⅰ=0.50mol·L^-^1, the ion-pair formation constant Q~i~p and ET rate constant k~e~t of the precursor complex for trans-[(en)~2(NO~2)Co(O~2CC~5H~5N)]^2^+/Fe(CN)~6]^4^- are 29mol^-^1·L and 2.4×10^-^1s^-^1, the activation enthalpy △H^≠~e~t and the activation entropy △S^≠~e~t of this ET process are 1.2×10^2kJ·mol^-^1 and 5.0×10^2kJ·mol^-^1·K^-^1 respectively. The intramolecular ET rate constant of the precursor binuclear complex for trans-[(en)~2(NO~2)Co(O~2CC~5H~4N)]^+/[Fe(CN)~5(H~2O)]^3^- is 7.0×10^-^5s^-^1 at 40℃, pH=8.0 and Ⅰ=-0.10mol·L^-^1. Finally the influence of the molecular orbital symmetry and the redox potentials on ET rate have been discussed.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, PYRIDINE P, INFRARED SPECTROPHOTOMETRY, REACTION KINETICS, ELEMENTAL ANALYSIS, CRYSTAL STRUCTURE, COBALT COMPLEX, ELECTRON TRANSFER REACTION, DIFFRACTION ANALYSIS

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