用Bis-mu-oxo二元体氧化碳化合物:电子转移,化物转移和原子转移机制
Anna S Larsen1, Kun Wang, Mark A Lockwood
1Department of Chemistry, University of Washington, Campus Box 351700, Seattle 98195-1700, USA.
Journal of the American Chemical Society
|August 22, 2002
概括
双氧和二元通过原子,电子或化物转移机制氧化基芳香化合物. 具体的途径取决于热化学和内在障碍,在介导氧化中显示出不同的反应性.
科学领域:
- 无机化学 无机化学 有机化学
- 氧化机制 氧化机制
- 有机金属化学 有机金属化学
背景情况:
- 基芳香化合物在工业过程和生物系统中普遍存在.
- 了解它们的氧化机制对于催化剂设计和反应控制至关重要.
- 众所周知,-oxo和-oxo二元体调解各种氧化反应.
研究的目的:
- 通过使用特定的二 manganese mu-oxo 和 mu-hydroxo 二次体来研究基芳香化合物的氧化.
- 阐明控制这些氧化过程的机制 (原子转移,电子转移,化物转移).
- 确定影响反应路径选择的热力学和动力学因素.
主要方法:
- 氧化反应的各种色基质 (二甲,香,,,,p-methoxytoluene,纳) 与二二元.
- 紫外线/Vis光谱动力学分析,以监测反应进展并识别中间体.
- 确定氧化还原电位和pKa值以评估转移热力学.
- 动态同位素效应研究探测速度决定步骤.
主要成果:
- 双二聚体 ([Mn(2)(O) ((2))) ((3+) 和[Mn(2)(O) ((OH) ((3+)) 通过原子转移氧化基质.
- 一种更强的氧化剂[Mn{2}{O}{2}}{4}+) 通过一些基质 (p-甲氧,纳) 的初始电子转移和其他基质 () 的化物转移来调解氧化.
- 托卢氧化时的动态同位素效应[Mn{2}{O}{2}{4}+) 表示在速度决定的步骤中发生了C-H键裂变.
- 热力学分析显示,虽然化物转移可能更容易,但由于较低的内在障碍,在某些情况下更喜欢电子转移.
结论:
- 氧二次体的氧化过程通过三个不同的机制进行:原子转移,电子转移和化物转移.
- 反应机制是由基质特性,氧化剂强度,热化学和内在动力障碍的组合决定的.
- 这项研究提供了对氧化催化过程中-氧合物复合物的反应性和机制多样性的基本见解.
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