Syntheses and crystal structures of mixed-ligand copper(II)–imidazole–carboxylate complexes

The syntheses, characterization, and crystal structures of the reaction products of Cu2+ with imidazole (Himz) and different aromatic carboxylates, viz.: [Cu(Himz)2(cinn)2(H2O)] (1), [Cu(Himz)2(paba)2] (2) and [Cu(Himz)2(clba)2] (3) (cinn– = C9H7O2–, paba– = C7H6NO2–, clba– = C7H4ClO2–) are described and studied by spectroscopic (UV–visible, FTIR) measurements. Single-crystal X-ray diffraction analyses indicate that each complex is monomeric. The metal ion in 1 adopts square-pyramidal coordination geometry arising from two imidazole nitrogens, two cinnamate oxygens, and an apical aqua. The metal ions of 2 and 3, however, assume a square planar configuration, which is realized by coordination of two nitrogens of two imidazoles and two oxygens; in both complexes, the imidazole moieties are trans to each other. TGA results indicate that upon heating, these complexes lose their carboxylate anions first, followed by removal of the imidazole molecules.