Metal complexes with pyridone-based radicals: Preparation and properties of a dinuclear paddle-wheel copper(II) complex and a mononuclear palladium(II) complex

We prepared and characterized dinuclear copper(II) and mononuclear palladium(II) complexes coordinated with a pyridine-based open-shell ligand, 5-(4′,4′,5′,5′-tetramethylimidazoline-3′-oxide-1′-oxyl)-2(1H)-pyridone (=HL). In the copper(II) dinuclear complex [Cu2(L)4(DMF)2] (1), four deprotonated ligands are coordinated as bridging ligands to form a paddle-wheel type unit. In the palladium(II) complex trans-[PdCl2(HL)2] (2), two HL ligands in the neutral hydroxypyridine form are coordinated to the trans positions of the metal ion via the nitrogen atoms. The hydroxyl groups of the ligands are hydrogen-bonded to the chlorine atoms of neighboring molecules, thereby creating a hydrogen-bonded double-chain molecular arrangement. Magnetic susceptibilities of these complexes were measured and analyzed. The small intramolecular antiferromagnetic interaction in the latter complex may originate from superexchange through the diamagnetic metal center.

By reaction of a pyridine-based open-shell ligand (HL) involving a nitronyl nitroxide moiety with copper(II) and palladium(II) ions, a dinuclear paddle-wheel type complex [Cu2(L)4(DMF)2] (1, figure) and a mononuclear complex trans-[PdCl2(HL)2] (2) were prepared. These complexes were characterized structurally and magnetically; the small intramolecular antiferromagnetic interaction in the latter complex may originate from superexchange through the diamagnetic metal center.Figure optionsDownload as PowerPoint slide