Copper complexes of some tetradentate pyrazolyl amines

Abstract

Four tetradentate nitrogen donor ligands have been prepared by condensation of N-hydroxymethylpyrazoles with ethylenediamines. These ligands are varied by methylation of the pyrazole rings (edbd) or the aminonitrogens (debp), or both (debd). Copper(II) complexes of the type CuL(ClO4)2 have been isolated with L = debp, edbp, edbd. For L = debd, the adducts salts Cu(debd)(dMp)X2, with X = ClO4-, BF4- and dMp = 3,5-dimethylpyrazole, were obtained. The compounds were characterized by their absorption (d-d) and EPR spectra. All four undergo quasi-reversible electrochemical reduction in methanol, the redox potentials being correlated with the degree of ligand methylation. The copper(I) forms are relatively unstable, and also bind carbon monoxide with different affinities. © 1988.