Crystal structures and magnetism of novel dinuclear dipicolinate compounds containing neocuproine

Abstract

Two novel dinuclear dipicolinate compounds of the formulae [Ni2(neo)(H2O)2(μ-dipic)(dipic)]∙6H2O (1) and [Co2(neo)(H2O)2(μ-dipic)(dipic)]∙0.5neo∙3H2O (2), where neo means neocuproine (2,9-dimethyl-1,10-phenanthroline) and dipic is dipicolinate (pyridine-2,6-dicarboxylate) ligand, have been synthesized, characterized by IR and VIS spectroscopy as well as by single crystal X-ray diffraction analysis and magnetic measurements. The Ni(II) or Co(II) metal centres are connected together through one μ-bridging dipicolinate ligand, while the second dipicolinate is only terminal chelating. The neocuproine molecule is in both cases coordinated in a bidentate chelating manner and the coordination sphere around Ni(II) or Co(II) atom is completed by terminal aqua ligands. Magnetic study revealed antiferromagnetic exchange interaction between the Ni(II) or Co(II) metal centres.