A metal-radical hetero-tri-spin SCM with methyl-pyrazole-nitronyl nitroxide bridges.

The preparation, crystal structures, and magnetic properties of a family of hetero-tri-spin 1-D coordination polymers with the formula [Ln(hfac)Cu(hfac)(4-NIT-MePyz)] (Ln = Gd, 1, Tb, 2, Dy, 3; hfac = hexafluoroacetylacetonate; 4-NIT-MePyz = 2-{4-(1-methyl)-pyrazolyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) are reported. In these complexes, the 4-NIT-MePyz radical acts as a linker to bridge the Cu and Ln ions through its pyrazole and aminoxyl groups to form a chain structure. Magnetic properties typical of spin-chains are observed for Dy and Tb derivatives but single-chain magnet (SCM) behavior was evidenced only for the Tb compound which is characterized by an energy gap for demagnetization / of 31 K.