Three new one-dimensional lanthanide complexes bridged by nitronyl nitroxide radicals: Crystal structures and magnetic characterization

Reaction of the nitronyl nitroxide radicals NIT-2thien or NIT-3Brthien with Ln(hfac)3·2H2O affords three new one-dimensional lanthanide–nitronyl nitroxide complexes [Ho(hfac)3(NIT-2thien)]n (1); [Ho(hfac)3(NIT-3Brthien)]n (2); [Eu(hfac)3(NIT-3Brthien)]n (3) (hfac = hexafluoroacetylacetonate; NIT-2thien = 2-(2′-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; NIT-3Brthien = 2-(3′-bromo-2′-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). They have been characterized by X-ray single crystal structure analysis, element analysis, infrared spectra, and direct current, alternating current magnetic susceptibility measurements. All compounds are composed of linear chains built up by Ln(hfac)3 units bridged by nitronyl nitroxide radicals through their NO groups. Magnetic studies reveal that the Eu-coordinated nitroxide and the radicals through the Eu atom interactions are antiferromagnetic.