Complexes of Cu(II), Co(II) and Ni(II) with pyrazole-derived ligands. Crystal structure of {bis[3-phenyl-5-(2-pyridyl)pyrazolato, kappa N-1 :kappa N-2]copper(II)}

The reaction of the pyrazole derived-ligands 3-phenyl-5-(2-pyridyl)pyrazole (HL0) and 3-phenyl-5-(6-methyl-2-pyridyl)pyrazole (HL1) with Cu((CHCOO)-C- 3)(2), Co(CH3COO)(2) and Ni(CH3COO)(2) was carried out. Products were chara cterised by elemental analyses, conductivity measurements and infrared and electronic spectroscopy. The IR spectra of complexes display the typical ab sorption bands of pyrazole-derived ligands. The nature of the complexes dep ends on the metal. M, the ligand, HL, and the M:HL ratio: Ni(HL)(2)(CH3COO) (2), Cu(L)(2), (HL = HL0, HL1), Co(L-0)(2). In the complexes of Co(II) and Cu(II) the pyrazole is deprotonated, the band nu (N-H) was not observed in IR spectroscopy. The crystal structure of [Cu(L-0)(2)] consists of discrete centrosymmetric molecules involving a co-ordinated CuN(pz)(2)N(py)(2) core with planar geometry. The anionic ligand L-0 is not completely planar. (C) 2001 Elsevier Science B.V. All rights reserved.