Syntheses, crystal structures and magnetic properties of two 2D copper–nitroxide coordination polymers bridged by flexible aliphatic dicarboxylate ligands

Two novel two-dimensional copper–nitroxide coordination polymers of formula [Cu2(NIT3Py)2(glu)2]n (1) and {[Cu2(NIT3Py)2(adip)2] · CH3OH · 0.5H2O}n (2) (NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, H2glu = glutaric acid and H2adip = adipic acid), have been synthesized and characterized structurally as well as magnetically. The crystal structures of both polymers contain the paddle-wheel binuclear Cu(II) units axially coordinated by NIT3Py ligands which are bridged by the flexible glutarate or adipate anions into the corrugated 2D sheets. Interestingly, complex 1 displays a 2D helical layer structure rarely found in metal–nitroxide systems. The magnetic measurements show the strong antiferromagnetic interactions in the binuclear Cu(II) units and weak antiferromagnetic interactions between copper ions and nitroxides.