一个非海姆硫酸盐结合超氧复合物:合成和光谱表征,计算研究,和原子抽象反应活性
Jesse B Gordon1, Avery C Vilbert2, Maxime A Siegler1
1Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States.
Journal of the American Chemical Society
|February 19, 2019
概括
合成和研究了一种新的-超氧复合物. 这种复合物与拟议的酶不同,它从OH键中抽取原子,而不是氧化硫供体,为金属酶选择性提供了洞察力.
科学领域:
- 无机化学 无机化学 有机化学
- 生物有机化学 生物有机化学
- 有机金属化学 有机金属化学
背景情况:
- 建议非海姆硫醇二氧化酶通过金属-超氧介质激活O2,该介质将S-氧化硫酸盐供体.
- 了解这种中间体的反应性对于阐明生物氧激活机制至关重要.
研究的目的:
- 为了合成和表征一种罕见的硫酸盐结合的-超复合物.
- 调查这个复合体对硫供体和O-H债券的反应性.
- 为了比较它的反应性与非海姆醇二氧化原酶中提出的机制.
主要方法:
- 合成和表征一个 ((II) dithiolato复合物.
- 与O2发生反应,形成一个-超物种.
- 谱学 (共振拉曼,EPR,X射线吸收) 和结构特征.
- 密度函数理论 (DFT) 的计算.
- 反应性研究涉及O-H键氧化和质子-合电子转移.
主要成果:
- 一种罕见的硫酸盐结合的-超复合物,Co(O2)(Me3TACN)(S2SiMe2),已成功生成和表征.
- 复合物没有S-氧化分子内或外源硫供体.
- 该复合物通过H原子抽象有效氧化了O-H键,其键解离自由能 (BDFE) 极限为≤70kcal mol-1.
- DFT计算支持观察到的反应性,预测BDFE为67kcalmol-1的假设的Co(OOH) 产品.
结论:
- 酸盐结合的-超物种表现出选择性,偏爱H原子抽象而不是S-氧化.
- 这一发现为参与氧化激活的非血金属酶的机械路径提供了关键的见解.
- 该研究强调了在金属酶功能中考虑替代反应模式的重要性,例如H原子抽象.
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