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) a nd Cu(HL0)(NO3)(2). 2H(2)O. The new complexes were characterised by element al analyses, conductivity measurements and infrared and electronic spectros copy. The crystal and molecular structure of [Cu(HL0)(NO3)(H2O)(2)](NO3) co nsists of discrete cations and NO3 anions linked by hydrogen bonds. The cat ion complex [Cu(HL0)(NO3)(H2O2)(2)](+) contains a copper(II) with a distort ed tetragonal pyramid geometry (tau = 0.094), with a H2O ligand occupying t he 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 ri ghts reserved.