Cobalt(II) complexes with pyrazole-derived ligands: Crystal structure of {bis[3-phenyl-5-(2-pyridyl) pyrazole]aquachlorocobalt(II)}chloride monohydrate

The synthesis of the new pyrazole-derived ligands 3-phenyl-5-(2-pyridyl) pyrazole (HL0) and 3-phenyl-5-(6-methyl-(2-pyridyl)) pyrazole (HL1) and their Co(II) complexes is reported. Elemental analyses, conductivity measurements and IR and UV-Vis spectroscopies defined all complexes. 1H and 13C NMR spectroscopies were also used in the characterization of ligands. The crystal and molecular structures of [Co(HL0)2Cl(H2O)]CL·H2O, consisting of discrete ions and water molecules linked by hydrogen bonds, are also reported. The hexacoordinated metal atom is bonded to two pyridinic nitrogens, two pyrazolic nitrogens (one of each nitrogen belonging to two different ligands), one chlorine atom and one water molecule, forming a distorted octahedral environment. The ligands are not exactly planar and the arrangement of ligands is cis, with a dihedral angle between the two mean planes of ligands of 89.21 (6)°. The degree of distortion from regular octahedral geometry is compared to that of closely related structures. (C) 2000 Elsevier Science Ltd.