Chromium and Manganese Complexes of Pincer‐Like Azo‐Amine Ligands: Synthesis, Characterization, and their Catalytic CC Bond Formation Reaction with Fluorenes and Alcohols

In this work, employing amine functionalized pincer‐like azo aromatic ligands, HL 1 and HL 2 , the synthesis of chromium complexes is reported, Cr1 and Cr2 , as well as manganese complexes, Mn1 and Mn2 , from the reaction of metal salts, CrCl 3 ·6H 2 O and MnCl 2 , respectively. The synthesized complexes are thoroughly characterized by various physicochemical characterizations, and finally, by single‐crystal X‐ray structure determination. Their geometric and electronic structures are further elucidated by cyclic voltammetry, electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. It was found that the metal in chromium complexes is in the +III oxidation state, and the metal in manganese complexes is in the +II oxidation state. Chromium complexes are less stable in solution compared to manganese complexes. However, examination of the redox properties shows that the first reduction is associated with ligand reduction in Cr as well as Mn‐complexes. Evaluation of the catalytic activity of these complexes in the reaction of CC bond formation in fluorene using alcohol as a reactant shows that the Mn(II)‐complexes are more efficient than the Cr(III)‐complexes. The Mn‐complexes are versatile and show very good functional group tolerance under mild reaction conditions.