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) py razole (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. H-1 and C-13 NMR s pectroscopies were also used in the characterization of ligands. The crysta l and molecular structures of [Co(HL0)(2)Cl(H2O)] Cl . H2O, consisting of d iscrete ions and water molecules linked by hydrogen bonds, are also reporte d. The hexacoordinated metal atom is bonded to two pyridinic nitrogens, two pyrazolic nitrogens tone of each nitrogen belonging to two different ligan ds), one chlorine atom and one water molecule, forming a distorted octahedr al environment. The ligands are not exactly planar and the arrangement of l igands is cis, with a dihedral angle between the two mean planes of ligands of 89.21(6)degrees. The degree of distortion from regular octahedral geome try is compared to that of closely related structures. (C) 2000 Elsevier Sc ience Ltd All rights reserved.