Pyrazoles and imidazoles as ligands. Part IX: Some adducts formed between Cu(II) salts and substituted pyrazoles

A number of adducts of general formula Cu(PZ)x2+(anion)2− is reported. In this formula PZ stands for: pyrazole. N-methyl pyrazole. 3(5)-methylpyrazole. 3,5-dimethylpyrazole. 4-chloropyrazole, 4-bromopyrazole and 4-nitropyrazole; the anions are ClO4−, BF4−, NO3−. Br− and Cl−. The value of x varies from 2–4 for the several ligands and anions. The compounds are synthesized from the hydrated Cu(II) salts and the stoichiometric amounts of pyrazoles in ethanol or acetone solutions, with the addition of triethyl orthoformate for dehydration. The adducts were characterized and identified by chemical analyses, infrared spectra, ligand-field spectra and paramagnetic measurements. In all compounds the Cu2+ ions were found to be in a six-coordinate, distorted octahedral environment. In contrast with other divalent metal ions, solvates containing the unit Cu(PZ)62+ could not be prepared.