强大的固定Cp*Ir转移化催化剂的激活和关闭:多元件在位X射线吸收光谱研究
Grant J Sherborne, Michael R Chapman, A John Blacker
1‡School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Journal of the American Chemical Society
|March 14, 2015
概括
本研究详细介绍了一种可回收的催化剂,用于转移化. 光谱分析揭示了催化剂如何变得活跃,并最终被禁用,为催化剂设计提供了洞察力.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
背景情况:
- 固定催化剂在分离和回收方面具有优势.
- 复合物广泛用于同质催化,特别是转移化.
- 了解催化剂失活路径对于改善催化剂寿命至关重要.
研究的目的:
- 在转移化过程中研究固定 [Cp*IrCl2]2 前催化剂的结构和电子变化.
- 阐明催化剂激活和失活的机制.
- 建立结构修改与催化性能之间的联系.
主要方法:
- 在Ir L3边缘,Cl K边缘和KK边缘进行X射线吸收光谱 (XAS).
- 在现场进行XAS实验以监测催化过程.
- 中毒和热过实验,以评估催化剂漏.
主要成果:
- 固定化的[Cp*IrCl2]2预催化剂显示出高强度和可回收性 (高达30倍).
- 光谱证据表明,作为激活步骤,一种化物配体与一种氧化物的交换.
- 失活是由于第二个化物连接体的交换,形成一种氧化物-酸盐物种.
结论:
- 活性预催化剂是由一个化物联体被一个氧化物替代而形成的.
- 催化剂失活是通过替换第二个化物连接体而发生的.
- 这些发现对于设计强大且可回收的同质和异质催化剂具有重要意义.
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