Magnetic and electronic characterization of 2:1 copper(II) complexes of a series of aminocarboxylic acids

Copper(II) complexes with L-(—)-proline, pipecolinic acid, picolinic acid, anthranilic acid, 4-chloranthranilic acid, 3,5,-dichloroanthranilic acid, 4-nitroanthranilic acid, N-phenyl-anthranilic acid, and flufenamic acid anions were prepared and characterized. The copper complexes of the anions of proline, pipecolinic acid, and picolinic acid are soluble in polar solvents and display frozen solution EPR spectra with axial resonance parameters. The copper complexes of the ring-substituted anthranilates are highly insoluble or only slightly soluble in a few solvents. The EPR spectra of the copper-doped zinc(II) analogues of these complexes display various degrees of rhombicity in their EPR parameters. The N-substituted anthranilates form insoluble complexes in aqueous solution which readily dissolve in organic solvents and undergo dimerization.