Merging Two Functions in a Single Rh Catalyst System: Bimodular Conjugate for Light-Induced Oxidative Coupling

A single molecular rhodium catalyst
system (PC2-Cp#RhIII) bearing two functional
domains for both photosensitization
and C–H carbometalation was designed to enable an intramolecular
redox process. The hypothesized charge-transfer species (PC2•–-Cp#RhIV) was characterized by spectroscopic
and electrochemical analyses. This photoinduced internal oxidation
allows a facile access to the triplet state of the key post-transmetalation
intermediate that readily undergoes C–C bond-forming reductive
elimination with a lower activation barrier than in its singlet state,
thus enabling catalytic C–H arylation and methylation processes.

研究人员设计了一种兼具光敏化与C-H碳金属化双重功能结构域的单分子铑催化剂体系（PC2-Cp#RhIII），以实现分子内氧化还原过程。通过光谱与电化学分析，对所提出的电荷转移物种（PC2•–-Cp#RhIV）进行了表征。该光诱导内氧化过程可便捷地获得转金属化后关键中间体的三重激发态，该中间体相较于其单重态，能够以更低的活化能垒快速发生C-C键形成还原消除反应，从而实现催化C-H芳基化与甲基化过程。