Crystal structures and magnetic properties of nitroxide radical-coordinated copper(II) and cobalt(II) complexes

The crystal structures and magnetic properties of three coordination compounds constructed from various nitroxide radicals L and M-II(hfac)(2)(H2O)(2) building blocks (M=Cu or Co and hfac=hexafluoroacetylacetonato) are described. In [(1)Cu(hfac)(2)](n), 4, the radical ligand L is coordinated to the metal through the oxygen atom of the nitroxide group and oxygen atom of its hydroxyl group, leading to a one-dimensional chain system. In [(2)(2)Cu(hfac)(2)](n), 5, two hydroxyl oxygen atoms of the radical ligand are coordinated to the metal, and the Co-II centers adopt distorted octahedral geometry to give a mononuclear compound. For [(L)Cu(hfac)(2)](n), 6, the oxygen atom of the nitroxide group and nitrogen atom of the amino group of L are coordinated to the metal, leading to a one-dimensional chain system. The magnetic susceptibility study of the copper coordination compound 4 revealed weak ferromagnetic interactions between the metal center and the organic radical. The cobalt coordination compounds 5 and 6 both show antiferromagnetic interactions.