Two Copper Complexes Based on Derivatives of Imidazo[1,5-a]pyridine: Syntheses, Structures, and Catalytic Properties

The syntheses, crystal structures and catalytic activities of two copper complexes are reported. Reaction of CuC l, 3-（pyridin-2-yl）imidazo[1,5-a]pyridine and pyridine-4-formaldehyde under solvothermal conditions gave [Cu;（L1）;Cl;][CuCl;];(1, L1 = 1,1?-（pyridin-4-ylmethylene）bis(3-（pyridin-2-yl）imidazo[1,5-a]pyridine). The ligand L1 was generated in situ from the reaction of 3-（pyridin-2-yl）imidazo[1,5-a]pyridine and pyridine-4-formaldhyde. The tetranuclear [Cu;（L1）;Cl;];moiety displays McClellan Saddle-like configuration. Reaction of Cu（BF;）;×6H;O with 1,1?-（pyridin-4-ylmethylene）bis(3-（pyridin-2-yl）imidazo[1,5-a]pyridine（L2） in glass tube generated [Cu（L2）(H;O);];[BF;];（SiF;）×2H;O（2）. The structures of 1 and 2 were characterized by Xray single-crystal diffraction analysis. The catalytic activities of 1 and 2 toward ketalization reactions were studied. They both exhibited high activities for the ketalization of aliphatic ketones by ethylene glycol.