Three new binuclear copper(II) complexes with isonicotinic acid N -oxide: syntheses, crystal structures and properties.

Three new copper(II) complexes with isonicotinic acid N -oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H 2 O)] 2 (NO 3 ) 2 ···2H 2 O ( 1 ), [Cu(L)(phen)(H 2 O)] 2 (ClO 4 ) 2 ···2H 2 O ( 2 ), and [Cu(L)(phen)Br] 2 - [Cu(L)(phen)(H 2 O)] 2 Br 2 ···6H 2 O ( 3 ) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu 2 dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N -oxide anion is bidentate, being coordinated to two Cu(II) ions through its N -O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie-Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes. [ABSTRACT FROM AUTHOR]