A Molecule Having 13 Unpaired Electrons: Magnetic Property of a Gadolinium(III) Complex Coordinated with Six Nitronyl Nitroxide Radicals

A gadolinium(III) complex coordinated with six nitronyl nitroxide radicals showed intriguing temperature-dependent changes in magnetic susceptibilities. The gadolinium(III) ion in the complex is pseudo-eight-coordinated by three singlet-ground-state diradical anion species based on nitronyl nitroxide radicals. The magnetic susceptibility (χpT) of the gadolinium(III) complex at 298 K, whose value corresponded to that of a system with 13 unpaired electrons (seven-spin system), decreased upon a lowering of the temperature to 11 K but increased upon a further lowering of the temperature. Finally, the χpT value at 2 K was found to be higher than that at room temperature. The temperature-dependent magnetic behavior could be explained by a structural change in the diradical anion ligand due to its flexibility.