Ising Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: a Key to Understand the Formation of Molecolar Magnetic Nanowires

The compound [Co(hfac)(2)-(NITPhOMe)(2)] (2) (hfac = hexafluoro-acetylacetonate, NITPhOMe = 4'-methoxyphenyl-4.4,5,5-tetramethylimidazo-line-1-oxyl-3-oxide) crystallizes in the triclinic P1 space group, a = 10.870(5), b = 11.520(5), c = 19.749(5) A, alpha = 78.05(5), beta = 84.20(5), gamma = 64.51(5)degrees, Z = 2. It can be considered a model system for studying the nature of the magnetic anisotropy of [Co(hfac)(2)-(NITPhOMe)] (1), which was recently reported to behave as a molecular magnetic wire. The magnetic anisotropy of 2 was investigated by EPR spectroscopy and SQUID magnetometry both in the polycrystalline powder and in a single crystal. The experimental magnetic anisotropy was related to the anisotropy of the central ion and to the exchange interaction between the cobalt(ii) ion and the radicals.