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缓慢的原子自我交换 Os(IV) 化物和 Os(III) 化物复合物之间:与电子和质子转移自我交换的关系
1Department of Chemistry, Campus Box 351700, University of Washington, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|October 2, 2003
概括
这项研究测量了涉及复合物的原子,质子和电子转移反应的速率. 它发现协调的原子转移是缓慢的,而质子和电子转移要快得多,这表明酸和的催化作用.
科学领域:
- 无机化学 无机化学
- 化学动力学 化学动力学
- 电子转移反应 电子转移反应
背景情况:
- 与氨酸和化连接体的复合物被研究了它们的氧化还原特性.
- 了解原子转移 (HAT) 和质子合电子转移 (PCET) 的机制在化学和生物学中至关重要.
研究的目的:
- 为了确定原子,质子和电子转移在Os (IV) /Os (III) 氨酸/化物系统中的自我交换和交叉反应速率.
- 为了比较协同HAT/PCET的速率与阶段性质子转移 (PT) 和电子转移 (ET) 途径.
- 研究固体阻碍和酸催化对这些转移反应的影响.
主要方法:
- 对氨酸 (IV) 和氨酸 (III) 复合物的动力学研究.
- 对HAT,PT和ET反应的自我交换率的测量.
- 分析交叉反应动力学与固体阻碍复合物和基基的分析.
主要成果:
- 在Os(IV) NHPh和Os(III) NH(2) Ph之间,合的原子转移 (HAT) 是显著缓慢的 (k(ex) ((H*) = 3 x 10(-3) M(-1) s(-1)).
- 相关的质子转移 (PT) 和电子转移 (ET) 自交反应的速度要快得多 (k = 10(3)-10(5) M(-1) s(-1)).
- 活性部位附近的绝缘散体会延缓H*和H(+) 的转移,而微量酸/基则通过逐步机制催化净H*转移.
结论:
- 协同HAT的缓慢性归因于前体复合物形成和/或非adiabatic动态的大量工作条件,而不是内在障碍.
- 在某些条件下,涉及快速ET和PT的逐步机制比协调的HAT/PCET更受青.
- 酸催化在促进这些系统中净原子转移方面发挥着重要作用.
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