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. [GRAPHICS] .