Slow relaxation of magnetization for a Tb derivative in a biradical-based lanthanide chain

A series of one-dimensional lanthanide chains [Ln(hfac)(3)(NITPh(4-NIT))](n) (Ln(iii) = Y 1, Gd 2, Tb 3 and Dy 4, hfac = hexafluoroacetylacetonate; NITPh(4-NIT) = 1,4-bis-(l '-oxyl-3 '-oxido-4 ',4 ',5 ',5 '-tetramethyl-4,5-dihydro-1H-imidazol-2 '-yl) benzene) based on a nitronyl nitroxide biradical ligand (NITPh(4-NIT)) has been successfully achieved and characterized. The NITPh(4-NIT) biradicals bridged Ln(hfac)(3) units through their NO groups of two mono-radicals to develop a one-dimensional chain with a 'zig-zag' motif. Magnetic investigation shows that within the biradical ligand, two unpaired electrons are delocalized and expected to be antiferromagnetically coupled. The magnetic behavior of complexes have been analyzed by using an appropriate magnetic model with antiferromagnetic [Ln-biradical] moieties. Moreover, the Tb complex reveals field induced slow magnetic relaxation, arising from the SIM behavior of the Tb(iii) center ion.