2 CU(HFAC)(2) COMPLEXES WITH THE IMIDAZOLINE NITROXIDE NO-2,2-DIMETHYL-5,5-DIMETHOXY-3-IMIDAZOLINE-1-OXYL - CONVERSION OF A DISCRETE MOLECULAR-STRUCTURE TO A CHAIN STRUCTURE AS A RESULT OF STOICHIOMETRIC CHANGES

The reaction of copper hexafluoroacetylacetonate with the stable nitro xide do-2,2-dimethyl-5,5-dimethoxy-3-imidazoline-1-oxyl (L) in a ratio of 2:1 in hexane yielded the Cu(hfac)(2)-saturated coordination chain polymer of composition [Cu(hfac)(2)](2)L. In [Cu(hfac)(2)](2)L, half of the Cu(hfac)(2) molecules coordinate L in bidentate-fashion by the amide-group oxygen and the imine nitrogen of the heterocycle. The othe r Cu(hfac)(2) molecules arrange the above {Cu(hfac)(2)L} fragments in polymer chains by alternate coordination of either the N-O group, or t he amide-group oxygens of two {Cu(hfac)(2)L} fragments to axial positi ons. As a result [Cu(hfac)(2)](2)L involves three copper ions with coo rdination number 6 and with different coordination environments. For m etal complexes with nitroxides, this mode of chain formation was obser ved for the first time. The magnetic properties of the complex are des cribed in terms of an exchange cluster model with ferromagnetic intrac luster exchange interactions.