快速电化学甲功能化涉及Pd-Pd结合中间体
R Soyoung Kim1, Evan C Wegener2, Min Chieh Yang3
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|November 24, 2020
概括
研究人员确定了一种关键的中间体的结构, 这种具有-键的双核 (III) 二元体解释了电催化甲激活的效率.
科学领域:
- 有机金属化学
- 电催化
- 光谱学
背景情况:
- 高价值的复合物可以使C-H键功能化.
- 电催化甲单功能化涉及Pd (II) 氧化到硫酸中的Pd (III) 中间体.
- 这种反应性中间体的结构和形成机制以前是未知的.
研究的目的:
- 确定甲功能化中的反应性,不可隔离的Pd (III) 中间体的结构.
- 阐明这种中间体的电化学形成的结构基础.
- 了解高价值的电催化甲激活的机制.
主要方法:
- 探测电子和结构性质的X射线吸收光谱 (XAS).
- 拉曼光谱识别振动模式和协调环境.
- 电子磁共振 (EPR) 光谱检测短暂的基质物种.
- 研究氧化潜力和反应热力学的电化学方法.
主要成果:
- 组装了一种具有Pd-Pd键的Pd (III) 模块作为甲激活中间体的结构模型.
- 每个中心都表现出硫酸连接体的5倍O原子协调.
- 在氧化过程中,一种具有金属-金属结合的混合价值Pd2 (II,III) 物种被确定为关键中间体.
- 热力学数据表明Pd二分化具有显著的驱动力 (Pd2[II,III]<4.5kcal/mol,Pd2[III]<9.1kcal/mol).
结论:
- 这项研究建立了Pd(II) 电化学氧化成金属与金属结合的Pd(III) 模块的结构基础.
- 在电化学氧化过程中,金属-金属和轴性金属-联体键的形成是Pd二元化的关键驱动因素.
- 这项工作为了解这些复合物的快速甲功能化反应提供了基础.
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