A four-spin ring with alternating magnetic interactions formed by pyridine-substituted nitronyl nitroxide radicals and Gd(III) ions: Crystal structure and magnetic properties

A novel complex, [Gd(hfac)3(NIT-5-Br-3py)]2 (hfac = hexafluoroacetylacetonat, NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) has been synthesized and characterized structurally and magnetically, in which a NIT-5-Br-3py molecular acts as a bridge ligand linking two Gd(III) ions through the oxygen atom of the N–O group and nitrogen atom from the pyridine ring to form a four-spin system. The fitting result of the magnetic susceptibility shows two different magnetic interactions between Gd(III) ion and NIT-5-Br-3py in one complex: a weak ferromagnetic interaction (J1 = +2.60 cm−1) through the N–O group, and a much weaker antiferromagnetic (J2 = −0.24 cm−1) interaction through pyridine ring.