Crystal structures and magnetic properties of nitroxide radical-coordinated copper(II) and cobalt(II) complexes
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The crystal structures and magnetic properties of three coordination compounds constructed from various nitroxide radicals L and MII(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)2Cu(hfac)2]n, 5, two hydroxyl oxygen atoms of the radical ligand are coordinated to the metal, and the CoII 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.
This work was supported by a Grant-in-Aid for Scientific Research (S) (No. 25220803) “Toward a New Class Magnetism by Chemically-controlled Chirality,” Chirality Research Center (CResCent) in Hiroshima University (the MEXT program for promoting the enhancement of research universities, Japan) and JSPS Core-to-Core Program, A. Advanced Research Networks.
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