PRESSURE IN COORDINATION CHEMISTRY .2. ANTIFERROMAGNETIC COMPLEXES OF COPPER(2)

The effect of high pressure (1-3000atm) on the magnetic properties of binuclear carboxylate complexes of copper(II), all of which exhibit pairwise antiferromagnetic interactions, is found to be surprisingly small, when the measurements are made on solutions in aprotic solvents oron the solids mulled in inert media. This indicates that there is little reduction in volume in going from the “triplet state”dimer (with one unpaired electron per copper) to the “singlet state” dimer (diamagnetic). The polymeric copper(II) oxalate behaves similarly. This result is bestexplained in terms of a weak copper-copper interaction, in the form ofa bond or a superexchange mechanism. In solutions containing “structure-breaking” solvents,such as ethanol or pyridine, there is an increase in magnetic susceptibility with increasing pressure, which is attributed to the dissociation of the bimolecular complexes. © 1969, American Chemical Society. All rights reserved.