高反应性CoIII,IV2(μ-O) 2钻石核心复合物,可以切割C-H键
Yan Li1, Suhashini Handunneththige2, Erik R Farquhar3,4
1Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics , University of Montana , Missoula , Montana 59803 , United States.
Journal of the American Chemical Society
|December 4, 2019
概括
化学家们开发了一种新的复合物,可以有效地激活强大的C-H键,模仿自然酶. 这种双复合体对C-H氧化表现出前所未有的反应性,进步了合成化学.
科学领域:
- 生物有机化学 生物有机化学
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
背景情况:
- 强 sp3 C-H 键的选择性激活对于生物和合成过程至关重要,但仍然是一个重大挑战.
- 大自然利用高价值二铁 (IV) 中间体 (如可溶性甲单氧酶) 来激活C-H键.
- 这些酶的现有合成模型在氧化强大的C-H键方面取得了有限的成功.
研究的目的:
- 合成和描述一种新型的高价值双复合物,作为C-H键激活的仿生模型.
- 研究这个复合体对强 sp3 C-H 键的反应性.
- 将其氧化能力与现有的第一排过渡金属复合物进行比较.
主要方法:
- 通过其CoIII2<μ-O>2前体 (2) 的氧化,合成一个CoIII,IV2(μ-O) 2复合体 (3),由一个tris(2-pyridylmethyl)amine (TPA) 配体支持.
- 使用X射线吸收光谱 (XAS) 和密度功能理论 (DFT) 计算进行了表征.
- 电子磁共振 (EPR) 谱学用于研究复杂的电子性质.
- 测量9,10-二甲 (DHA) 氧化速率常数的动力学研究.
主要成果:
- 一个高价值的CoIII,IV2(μ-O) 2复合体 (3) 具有钻石核心结构和短的Co··Co距离 (2.78 Å) 已成功生成.
- 复合体3是EPR活跃的,表现出S = 1/2信号,具有来自Co.59的特征性超细分离.
- 复合物3作为sp3 C-H键的氧化剂表现出异常高的反应性,DHA氧化速率常数显著超过Mn,Fe和Cu类型.
- 复合体3的反应性比之前报告的二铁复合体大4-5个数量级.
结论:
- 合成的迪科巴尔特复合物代表了一种高度活跃的合成氧化剂,可以挑战sp3 C-H键.
- 这种生物启发的双系统为开发更有效的C-H激活策略提供了一个有前途的平台.
- 这些发现为设计基于地球上丰富的金属用于C-H功能化的未来催化剂提供了宝贵的见解.
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