Visible‐light capture activates a thermodynamically inert Co^III−CF₃ bond for direct C−H trifluoromethylation of arenes and heteroarenes. New trifluoromethylcobalt(III) complexes supported by a redox‐active [OCO] pincer ligand were prepared. Coordinating solvents, such as MeCN, afford green, quasi‐octahedral [(^SOCO)Co^III(CF₃)(MeCN)₂] (2), but in non‐coordinating solvents the complex is red, square pyramidal [(^SOCO)Co^III(CF₃)(MeCN)] (3). Both are thermally stable, and 2 is stable in light. But exposure of 3 to low‐energy light results in facile homolysis of the Co^III−CF₃ bond, releasing ^.CF₃ radical, which is efficiently trapped by TEMPO^. or (hetero)arenes. The homolytic aromatic substitution reactions do not require a sacrificial or substrate‐derived oxidant because the Co^II by‐product of Co^III−CF₃ homolysis produces H₂. The photophysical properties of 2 and 3 provide a rationale for the disparate light stability.

中文翻译：

---

光诱导钴（III）-三氟甲基键激活使芳烃CH三氟甲基化

可见光捕获激活了热力学惰性的Co ^III -CF ₃键，用于芳烃和杂芳烃的直接CH-H三氟甲基化。制备了具有氧化还原活性[OCO]钳位配体的新型三氟甲基钴（III）配合物。配位溶剂（例如MeCN）可得到绿色的半八面体[（^S OCO）Co ^III（CF ₃）（MeCN）₂ ]（2），但在非配位溶剂中，络合物为红色，方形锥体[[ ^S OCO ）Co ^III（CF ₃）（MeCN）]（3）。两者都是热稳定的，而2在光照下是稳定的。但是曝光3到低能量的光会导致Co ^III -CF ₃键的均质溶解，释放出来^。CF ₃自由基，被TEMPO有效捕获^。或（杂）芳烃。均质芳族取代反应不需要牺牲性或底物衍生的氧化剂，因为Co ^III -CF ₃均质化的Co ^II副产物可产生H ₂。2和3的光物理性质为不同的光稳定性提供了理论依据。