Synthesis, structures and magnetic properties of copper (II) and cobalt (II) complexes containing pyridyl-substituted nitronyl nitroxide and 3,5-dinitrobenzoate

Four new metal-radical complexes - [Cu(NIT3Py)2(DTB)2] 1, [Co(NIT3Py)2(DTB)2(CH3OH)2] 2, [Cu(NIT4Py)2(DTB)2(H2O)2] 3, [Co(NIT4Py)2(DTB)2(H2O)2] 4, (NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], NIT4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], DTB = 3,5-dinitrobenzoic anion) have been synthesized by using transition metal ions, nitronyl nitroxide radicals as spin carriers, and incorporating 3,5-dinitrobenzoic acid (DTB) as a coligand.The structures of 1–4 were determined by X-ray single-crystal analyses. Complex 1 has a square planar geometry, where the Cu(II) ion is located in the central site of the rectangle and two radicals and two DTBA ligands are trans-coordinated to the Cu(II) ion. The other three complexes (2-4) have similar structures, in which two radicals, two DTBA ligands and two solvent molecules act as terminal ligands to form six coordinate distorted octahedrons. The magnetic behaviors of these compounds indicate that antiferromagnetic exchanges exist between the radical ligands and the metal ions, and their magnetic properties are explained by their structures and a magnetic exchange mechanism.

Four new metal-radical complexes have been synthesized by using transition metal ions and nitronyl nitroxide radicals as spin carriers, and incorporating 3,5-dinitrobenzoic acid (DTB) as a coligand. All the complexes show antiferromagnetic interactions. The correlation of crystal structures and magnetic properties in connection with the magnetic exchange mechanism is discussed.Figure optionsDownload as PowerPoint slide