Mononuclear and Tetranuclear Copper(II) Complexes Bearing Amino Acid Schiff Base Ligands: Structural Characterization and Catalytic Applications
Karla-Alejandra López-Gastélum,
Enrique F. Velázquez-Contreras,
Juventino J. García,
Marcos Flores-Alamo,
Gerardo Aguirre,
Daniel Chávez-Velasco,
Jayanthi Narayanan,
Fernando Rocha-Alonzo
Affiliations
Karla-Alejandra López-Gastélum
Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Rosales and Luis Encinas s/n, Col. Centro, Hermosillo 83000, Sonora, Mexico
Enrique F. Velázquez-Contreras
Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Rosales and Luis Encinas s/n, Col. Centro, Hermosillo 83000, Sonora, Mexico
Juventino J. García
Facultad de Química, Universidad Nacional Autónoma de México, Circuito Exterior Cd. Universitaria, Coyoacán, Ciudad de México 04510, Ciudad de México, Mexico
Marcos Flores-Alamo
Facultad de Química, Universidad Nacional Autónoma de México, Circuito Exterior Cd. Universitaria, Coyoacán, Ciudad de México 04510, Ciudad de México, Mexico
Gerardo Aguirre
Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana 22000, Baja California, Mexico
Daniel Chávez-Velasco
Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana 22000, Baja California, Mexico
Jayanthi Narayanan
División de Ingeniería en Nanotecnología, Universidad Politécnica del Valle de México, Av. Mexiquense s/n esquina Av. Universidad Politécnica, Col. Villa Esmeralda, Tultitlan 54910, Estado de México, Mexico
Fernando Rocha-Alonzo
Departamento de Ciencias Químico Biológicas, Universidad de Sonora, Calle Rosales y Blvd. Luis Encinas s/n, Col. Centro, Hermosillo 83000, Sonora, Mexico
Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%).
