The Isolation and Characterization of Square Planar, Square Pyramidal, and Octahedral Copper(II) Complexes with Mixed Ligands

Abstract

Substitution of an acetylacetonate by a carboxylate in the neutral (acac)2Cu(II) was achieved by its reaction with tri- and dichloroacetic acid in benzene (HCO2R where R = CCl3 or CHCl2; Hacac = acetylacctone) which led to the formation of the mixed chelate square planar complex (acac)Cu(OCOR). The later complex, R = CCl3, reacted with heterocyclic bases to produce the square pyramidal complexes (acac)Cu(OCOR) (base), (base = 2- methylpyridine or quinoline); with ethylenediamine (en) to give the octahedral [(en)2Cu(OCOR)]Cl, and with methanol and piperidine or boiling methanol alone to give the methoxo-bridged (acac)Cu(OCH3)2Cu(acac). The reaction of acetylacetonate-carboxy- late-copper(II) complex (R = CHCl2) with heterocyclic bases led to the cleavage of the acetylacetonate ligand and the formation of the octahedral Cu(OCOCHCl2) · 2 base (base = pyridine, 2-, 3- or 4-methylpyridine). The same cleavage reaction took place, and also with R = CCl3, in their reaction with 8-hydroxyquinoline to form the mixed chelates (ROCO)Cu(Oxinate). These formulations are based on chemical analyses, electronic and vibrational spectra, and on conductance measurements.