2,2′-Bipyridyl-acetylphenolato mixed ligand copper(II) complexes: syntheses, characterizations and catalytic activity in styrene epoxidation

Abstract

Two copper(II) complexes, [Cu(bipy)(5-Br-2-hap)(ClO₄)]₂ (1) and [Cu(bipy)(2-hap)(ClO₄)] (2) (where bipy = 2,2′-bipyridine, 5-Br-2-hap = 5-bromo-2-hydroxyacetophenone, 2-hap = 2-hydroxyacetophenone), were synthesized and characterized. The crystal structure of 1 was determined by single crystal X-ray diffraction while 2 was reported earlier. Structural characterization reveals that the presence of bromine in 5-Br-2-hap plays a structure-determining role in dimeric 1 in comparison with the mononuclear 2 where 2-hap was used. Studies of the catalytic potential toward styrene epoxidation in homogeneous system using H₂O₂ as oxidant reveal that 1 is more efficient than 2 with respect to epoxide selectivity.

Keywords:

• Mixed ligand copper(II) complexes
• Spectral and structural characterizations
• Homogeneous catalysis
• Hydrogen peroxide
• Styrene epoxidation

Acknowledgements

S.S. gratefully acknowledges the Department of Chemistry, Krishnagar Government College for providing financial support and infra-structural facilities. U.Y. is thankful to Department of Science and Technology, New Delhi, Government of India for providing financial assistance through Fast Track Young Scientist Scheme (Ref. No. SR/FT/CS-78/2010).