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铁复合物的原子转移反应的基本状态变化很大
Elizabeth A Mader1, Ernest R Davidson, James M Mayer
1University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|April 4, 2007
概括
铁复合物经历了与TEMPO的原子转移 (HAT) 反应,产生了意想不到的大变化. 这些发现挑战了假设,并强调了振动在涉及过渡金属的HAT反应中的重要性.
科学领域:
- 协调化学 协调化学
- 物理化学 物理化学
- 化学动力学 化学动力学
背景情况:
- 原子转移 (HAT) 反应是化学的基础.
- 滴定性铁tris ((alpha-diimine) 复合物以其氧化还原活性而闻名.
- 传统的HAT反应通常假定变化微不足道.
研究的目的:
- 为了研究铁的原子转移 (HAT) 反应 (FeII) 三[2,2'-bi-1,4,5,6-tetrahydropyrimidine]二化物 (FeII(H2bip)) 和铁的三[2,2'-bi-2-imidazoline]二化物 (FeII(H2bim)) 与TEMPO.
- 确定这些HAT反应的热力学参数,包括变化.
- 为了阐明在这些以铁为中心的HAT反应中观察到的显著变化的起源.
主要方法:
- 静态和动态测量以确定酸中的基态热力学参数.
- 电子转移半反应的测量.
- 不受限制的哈特里-福克 (UHF)/6-31G*计算计算.
主要成果:
- 两个FeII(H2bip) 和FeII(H2bim) 复合体都成功地将H*转移到TEMPO.
- 在两种HAT反应中都观察到显著的非零变化 (T
- 大量的变化主要归因于铁中心氧化时的振动变化,而不是溶剂效应或结合.
结论:
- 该研究表明,涉及过渡金属中心的HAT反应中的变化可以显著偏离零.
- 与金属中心的氧化状态相关的振动变化是观察到的大变化的主要驱动因素.
- 在评估涉及过渡金属的HAT反应的驱动力时,应优先考虑自由能量,而不是度.
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