Theoretical Study of Ru-Catalyzed Decarboxylative Heteroarylation of Aryl Carboxylic Acids

The <i>ortho</i>-di(2-pyridyl)arenes, featuring a unique structure, hold significant promise for applications in fluorescent probes, synthetic nanoparticle stabilizers, and chemical synthesis. The mechanism of Ru-catalyzed decarboxylation and heteroarylation reactions of aryl carboxylic acids to access <i>ortho</i>-dipyridylarenes was elucidated using DFT calculations, which involved C-H bond activation, oxidative addition, reductive elimination, and decarboxylation processes to form <i>ortho</i>-di(2-pyridyl)arenes. The rate-determining step of the reaction is the second reductive elimination step with an energy barrier of 27.1 kcal/mol. The calculated results indicated that the ligand 1,10-phenanthroline will promote the first C-C coupling process and inhibit the second C-C coupling process, while the aryl carboxylic acids will promote the second C-C coupling reaction. In addition, the origin of selectively generating <i>ortho</i>-di(2-pyridyl)arenes was revealed due to the high energy barrier of forming <i>ortho</i>-tri(3-pyridyl)arenes. These insights aid in optimizing reaction conditions and designing efficient catalytic processes for the synthesis of <i>ortho</i>-di(2-pyridyl)arenes.