Crystal structure, spectroscopic characterisation and magnetic properties of [Cu(BIP)(N3)]·H2O (BIP=3,3-bis(2-imidazolyl)propionate), a copper(II) polymeric compound with asymmetrical μ-1,3-azido bridges

The structure and the spectroscopic and magnetic properties of [3,3-bis(2-imidazolyl)propionato]azidocopper(II) monohydrate are described. The compound is built of [Cu(BIP)N3] entities which are connected through carboxylate groups from the BIP molecules —which act as a tridentate ligand—and asymmetrical μ-1,3-azido bridges, leading to a polymeric sheet-like structure. The copper atom is involved in a CuN3ON′ chromophore and lies in a distorted square-pyramidal environment. Both electronic and EPR spectra are indicative of an essentially dx2−y2 ground state for the copper(II) ions. Magnetic susceptibility measurements in the range 1.8–200 K show very weak antiferromagnetic exchange between the copper(II) ions (2J=−0.48 cm−1). This feature is discussed on the basis of the relative orientation of the coordination polyhedron around the metal atom and the bridging network.