Copper(II) complexes derived from bidentate N,O-ligands for catalytic aerobic oxidation

• Two mononuclear copper(II) complexes based on N,O-ligands were synthesized.
• The complexes feature different coordination geometries on Cu(II) centers.
• Both complexes catalyzed aerobic alcohol oxidations in an aqueous media.
• Complex with a square-planar Cu(II) center displayed higher catalytic reactivity.

Two CuII complexes based on bidentate N,O-ligands have been synthesized and structurally characterized. X-ray structural analysis revealed that in complex 1 the CuII center adopts an unusual near tetrahedral coordination geometry, while the CuII core in 2 is traditionally square planar, albeit both of them have a N2O2 coordination environment and two compounds are mononuclear bis-ligand neutral complexes. A two-dimensional sheet-like network was observed in 2, resulting from the weak Cu…O contacts between the nitrato groups and axial CuII sites. Both complexes were tested for catalytic aerobic oxidation of benzylic alcohol and the results indicated that 2 was a better catalyst than 1. High yield of benzaldehyde was observed when using 2 as a catalyst in combination with TEMPO in an aqueous potassium carbonate solution at 60 °C.

Two CuII complexes based on bidentate N,O-ligands have been synthesized and structurally characterized by X-ray diffraction analysis. The CuII centers in two complexes adopt different coordination geometries, and catalytic tests revealed that the complex with a traditional square-planar geometry CuII displayed much higher catalytic activity for the aerobic oxidation of benzylic alcohol than that having a nearly tetrahedral CuII core.Figure optionsDownload as PowerPoint slide