Two copper(II)-nitronyl nitroxide radical dimers with a bulky β-diketonate: Synthesis, structure and magnetic behavior

Two copper(II) compounds with pyridyl substituted nitronyl nitroxide radicals were synthesized and magnetically characterized: [Cu(FOD)2(NITpPy)] (1) and [Cu(FOD)2(NIToPy)] (2) (FOD = 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione, NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and NIToPy = 2-pyridyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). The crystal structures of both compounds were solved and showed that (1) is the first magnetic dimer in which the NITpPy radical is coordinated to a [Cu(β-diketonate)2] building block only by the pyridinic nitrogen atom, whereas in (2) the NIToPy radical is coordinated to metal ion through nitroxide and pyridyl groups. The magnetic coupling between the spin carriers in compound (1) is of antiferromagnetic nature while in (2) is ferromagnetic.