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

摘要

We prepared and characterized dinuclear copper(Il) and mononuclear palladium(II) complexes coordinated with a pyridine-based open-shell ligand, 5-(4',4',5',5'-tetramethylimidazoline-3'-oxide-l'-oxyl)-2(IH)-pyridone (=HL). In the copper(11) dinuclear complex [Cu-2(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. (c) 2005 Elsevier Ltd. All rights reserved.