Cu(II) complexes with pyrazole-derived ligands.: Crystal structure of {[diaquanitrato(3-phenyl-5-(2-pyridyl)pyrazole)]copper(II)} nitrate

Reaction of the ligands 3-phenyl-5-(2-pyridyl)pyrazole (HL0) and 3-phenyl-5-(6-methyl-(2-pyridyl))pyrazole (HL1) with Cu(NO3)(2). 3H(2)O and CuX2. xH(2)O (X = Cl, Br) gives complexes with stoichiometry Cu(HL0)(2)X-2. xH(2)O, Cu(HL1)(2)X-2. EtOH, Cu(HL)X-2, Cu(HL)(2)(NO3)(2). xH(2)O (HL = HL0, HL1) and Cu(HL0)(NO3)(2). 2H(2)O. The new complexes were characterised by elemental analyses, conductivity measurements and infrared and electronic spectroscopy. The crystal and molecular structure of [Cu(HL0)(NO3)(H2O)(2)](NO3) consists of discrete cations and NO3 anions linked by hydrogen bonds. The cation complex [Cu(HL0)(NO3)(H2O2)(2)](+) contains a copper(II) with a distorted tetragonal pyramid geometry (tau = 0.094), with a H2O ligand occupying the apical site. The penta-coordinated metal atom is bonded to one pyridinic nitrogen, one pyrazolic nitrogen, one nitrate and two water molecules. The ligand HL0 is not completely planar. (C) 2001 Elsevier Science Ltd. All rights reserved.