Synthesis, structure, network and thermal analysis of four 5-(pyrazinyl)tetrazolato copper(II) and cobalt(II) complexes

Artikel i vetenskaplig tidskrift, 2007

Three new copper complexes and one cobalt complex with 5-(pyrazinyl)tetrazolate anion, (pyztz)(-), as chelating bidentate ligand, were obtained by the reaction of pyrazinecarbonitrile with sodium azide in the presence of copper(II) nitrate or cobalt(II)chloride. Complexes of composition [Cu(pyztz)(2)(H2O)] (1) deep blue crystals, [Cu(pyztz)(2)(H2O)(2)] (2a) green crystals, [Co(pyztz)(2)(H2O)(2)] (2b) orange crystals, [Cu(pyztz)2(H2O)(2)] center dot (H2O) (3) blue crystals were obtained. The single crystal X-ray diffraction revealed that complex I has square pyramidal structure with one water molecule at apical and two pyrazine-tetrazolato ligands at basal sites, while structures of 2a, 2b and 3 consist of octahedrally coordinated metal ions, where two pyztz anions act as bidentate ligands via one of the pyrazine-N atoms and one of the tetrazole-N atoms in trans-positions and two trans water molecules. Complex 3 contains one extra lattice water molecule. Hydrogen bonds of the types O-H center dot center dot center dot O and O-H center dot center dot center dot N connect the mononuclear units to a three-dimensional network structure in 2 (a and b are isostructural) and 3. Although the H-bond patterns look complex it is shown that they can be related to the well-known three- and six-connected rutile net (rtl) in 2 and the four- and six-connected fsh-net in 3. (C) 2006 Elsevier Ltd. All rights reserved.