Lanthanide–radical linear chain compounds based on 2,4,4,5,5-pentamethylimidazoline-1-oxyl-3-oxide: Structure and magnetic properties

Two one-dimensional nitronyl nitroxide–lanthanide complexes [Ln(hfac)3(NITMe)]n (Ln(III) = Y (1), Dy(2), hfac = hexafluoroacetylacetonate; NITMe = 2,4,4,5,5-pentamethylimidazolyl-1-oxyl-3-oxide) have been successfully prepared and characterized. Single crystal X-ray crystallographic analysis reveals that complexes 1 and 2 show similar linear chain structures composed of Ln(hfac)3 units bridged by NITMe radicals through their NO groups. Variable-temperature magnetic susceptibilities of Y complex show that there exists weak antiferromagnetic coupling between the radical ligands through the diamagnetic Y(III) ions. Alternating current (ac) susceptibilities of Dy complex reveal frequency dependent out-of-phase signals, indicating that it behaves as single-chain magnet.