Synthesis and Magnetism of Rare Earth Binuclear Complexes with Bridging Nitronyl Nitroxides

Abstract

Six compounds of the general formula [Ln(pfpr)₈]₂(NITphMe). nH₂O, where Ln = Nd, Gd, Dy, Ho, Er, Y, pfpr = pentafluoropropionate, NITphMe = 2-(4-methylphenyl)−4,4,5–5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide, and n = 4 (for Nd, Gd); 2 (for Dy); 6 (for Ho); 0 (for Er); 5 (for Y), have been synthesized. These complexes were characterized by elemental analyses, IR, electronic spectra and molar conductances. The variable temperature (4–300 K) magnetic susceptibility of the complex [Gd(pfpr)₈]₂(NITphMe). 4H₂O was determined. The observed susceptibility data were fit to those from the theoretical magnetic equation by the least-squares method. The exchange integral, J, was found to be equal to 0.263 cm⁻¹. This indicates weak ferromagnetic spin-exchange interaction between the radical and the gadolinium(III) ion.