Copper(II) complexes of N-heteroaromatic hydrazones: Synthesis, X-ray structure, magnetic behavior, and antibacterial activity

Three novel copper(II) complexes as condensation derivatives of 2-pyridinecarboxaldehyde, 2-acetylpyridine or 2-quinolinecarboxaldehyde with ethyl hydrazinoacetate hydrochloride were synthesized. X-ray crystal structures of all three complexes were determined. Crystallographic data indicate a common basis of the structures with some major differences. Both pyridine derivatives form complexes of the type [CuCl2L] with distorted square-planar geometry around copper(II), but show a decisive difference in the side chain orientation. The quinoline derivative forms a dimeric complex of type [Cu2Cl4L2] with distorted trigonal bipyramidal geometry around copper(II), but a rather short Cu···Cu contact, which is reflected in its magnetic properties. All three complexes showed antibacterial activity.