后期金属中心之间的超快和超慢的氧原子转移反应
Kevin C Fortner1, David S Laitar, John Muldoon
1Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA.
Journal of the American Chemical Society
|January 18, 2007
概括
氧化三聚利 (V) 和 (III) 复合物在室温下迅速转移氧原子. 这种独特的反应性使得能够激活用于催化氧化的二氧化物,与较慢的类似物不同.
科学领域:
- 有机金属化学 有机金属化学
- 无机化学 无机化学 有机化学
- 催化剂是一种催化剂.
背景情况:
- 金属-氧气键在各种化学转化中至关重要.
- 了解金属间原子转移机制是设计高效催化剂的关键.
- 和复合物以它们的催化作用而闻名.
研究的目的:
- 为了研究oxotrimesityliridium(V) 和trimesityliridium(III) 复合体之间的退化的金属间氧原子转移.
- 为了比较和复合物的氧原子转移速率.
- 阐明控制观察到的反应性差异的因素,并探索它们的催化应用.
主要方法:
- 可变温度核磁共振 (NMR) 光谱法用于测量解离速率.
- 低温光学光谱测量以确定对比平衡.
- 一个mu-oxo二元模拟物的晶体学表征.
主要成果:
- 氧化三聚利 (V) 和 (III) 复合体表现出极快的氧原子转移 (k = 5 x 10^7 M^-1 s^-1).
- 奥斯复合物表现出明显较慢的氧原子转移 (k = 1.8 x 10^-5 M^-1 s^-1),尽管具有相似的金属氧键强度.
- -交换率与马库斯理论一致,这表明重组能量差异是关键.
结论:
- 复合体中金属间氧原子的快速转移归因于有利的电子和结构因素,允许低的重组能量.
- 在复合体中显著较慢的速度是由于对金字塔化不利的电子要求.
- 氧化的独特反应性使其能够在催化氧化过程中作为二氧化激活剂,如烯酸二氧化和酒精氧化.
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