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)2·3H2O and CuX2·xH2O (X= Cl, Br) gives complexes with stoichiometry Cu(HL0)2X2·xH2O, Cu(HL1)2X2·EtOH, Cu(HL)X2, Cu(HL)2(NO3)2·xH2O (HL = HL0, HL1) and Cu(HL0)(NO3)2·2H2O. 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](NO 3) consists of discrete cations and NO3- anions linked by hydrogen bonds. The cation complex [Cu(HL0)(NO3)(H2O)2]+ contains a copper(II) with a distorted tetragonal pyramid geometry (τ = 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. © 2001 Elsevier Science Ltd.