DIMERIC COPPER(II) COMPLEXES WITH BRIDGING UNSATURATED CARBOXYLIC LIGANDS. CORRELATION OF pKa VALUES AND MAGNETIC EXCHANGE PARAMETERS

Abstract

The copper(II) salts∗ of acrylate, crotonate and 3,3′-dimethyl-acrylate anions exist with reduced magnetic moments. Magnetic susceptibility measurements (80–300 K) revealed the strong antiferromagnetic exchange coupling between the copper(II) ions. Singlet-triplet separation values obtained by least-squares fitting to the modified Bleaney-Bowers equation are equal to −302, −305 and −324 cm⁻¹, respectively. Unusual EPR spectra of these compounds, which, besides lines due to dimeric units, also exhibit the lines characteristic for polymeric copper(II) chains (g ≈2.10) are the basis for discussion of the molecular structures of the compounds.