Copper(II) and nickel(II) complexes of pyrazole derived ligands: Synthesis, characterization and coordinating properties of two substituted thiocarbamyl pyrazoles, 3,5-dimethyl-1-N-methyl/ethyl thiocarbamyl pyrazole (HL1, HL2), potential ligands for biological interest. X-ray crystallographic studies of Ni(L-2)(2)

The solid complexes of Cu(II) with different counterions and Nio(II) having no counterions with 3,5-dimethyl-1-N-methyl thiocarbamylpyrazole (HL1) and 3,5-dimethyl-1-N-ethyl thiocarbamylpyrazole (HL2), the ligands having coor dination function of the pyrazole ring and the thiocarbamido group, have be en prepared and their geometries established on the basis of molar conducta nce, magnetic susceptibility, IR, UV and visible spectral data. Magnetic an d spectral features indicate paramagnetic [Cu(HL1/HL2)X-2] (X = Cl, Br), [C u(HL1/HL2)(2)] (ClO4)(2) as either planar or tetragonally distorted octahed ral species with the ligands in the neutral "thione" form, while Ni(L-1/L-2 )(2) as the diamagnetic square planar species with the ligands in the depro tonated "thiol" form. X-ray crystallographic studies of Ni(L-2)(2) has unam biguously proved the distorted square planar environment around the central nickel(II) ion; the ligand molecules are cis-coordinated to the nickel(II) ion. (C) 1998 Elsevier Science Ltd. All rights reserved.