STRUCTURAL, SPECTROSCOPIC AND MAGNETIC CHARACTERIZATION OF AQUABIS(CROTONATO)BIS(IMIDAZOLE)COPPER(II)

The X-ray crystal structure of [Cu(crot)(2)(im)(2)(H2O)] (crot = 2-but enoate(crotonate) anion; im = imidazole) has been determined by X-ray diffraction methods. The compound is built of neutral [Cu(crot)(2)(im) (2)(H2O)] entities linked through hydrogen bonds involving water molec ules and carboxylate groups to give a chain structure running along th e b axis. The copper atom is involved in a CuN2O2O' chromophore and li es in a distorted square-pyramidal environment. Both electronic and EP R spectra are indicative of an essentially d(x2-y2) ground state for t he copper(II) ions. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is d iscussed on the basis of the relative orientation of the coordination polyhedron around the metal atom and the bridging network. Copyright ( C) 1996 Elsevier Science Ltd