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[Cu4(L1)2Cl2][CuCl2]2(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[Cu4(L1)2Cl2]2+moiety displays McClellan Saddle-like configuration.Reaction of Cu(BF4)2×6H2O with 1,1´-(pyridin-4-ylmethylene)bis(3-(pyridin-2-yl)imidazo[1,5-a]pyridine(L2)in glass tube generated[Cu(L2)(H2O)2]2[BF4]2(SiF6)×2H2O(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.