Synthesis, spectroscopic and magnetic properties of copper(II) complexes of novel polyaza chain molecules

Abstract

The coordination of copper(II) chloride to the large linear polyazadioxime molecules 4,4-diaza-3,6-dimethyl-3,5-octadiene-2, 7-dione-2,7-dioxime and -4,5,8,9-tetraaza-3,6,7,10-tetramethyl-3,5,7,9-dodecatetraene-2,11-dione-2,11-dioxime (abbreviated, respectively, H 2doxN 2 and H 2doxN 4) has been studied. These polymetallic complexes are an unusual route for bridging paramagnetic ions through a direct polyatomic pathway to give an antiferromagnetic linear chain of the ribbon type. Without available X-ray data the molecular geometries of the polymetallic compounds are characterized by vibrational, electronic and EPR spectroscopy, as well as by magnetic susceptibility measurements between 300 and 4.2 K. The binuclear Cu 2(H 2doxN 2)Cl 4 complex shows antiferromagnetic intradimer super exchange, 2 J = −38 cm −1, and the trinuclear Cu 3(H 2 doxN 4)Cl 6 complex shows antiferromagnetic intratrimer superexchange between neighbouring centres, 2 J = −25 cm −1, propagated throu