A new family of heterometallic LnIII [12-MCFe IIIn(Shi)-4] complexes: Syntheses, structures and magnetic properties

Abstract

A new family of LnIII [12-Metallacrown-4] compounds of formulas (C5 H6 N) [LnFe4 (shi)4 (C6 H5 COO)4 (Py)4]·3.5Py [Ln = EuIII (1); GdIII (2); TbIII (3); DyIII (4); and, H3 shi = salicylhydroxamic acid] were obtained through one-pot reactions with H3 shi, Fe(NO3)3·9H2 O, and, Ln(NO3)3·6H2 O as reagents. Single-crystal X-ray analyses show that they are isostructural and have the similar [12-MCFe IIIN(shi)-4] core, with four benzoate molecules bridging the central LnIII ion to the ring FeIII ions. The negative charge of the 12-MC-4 metallacrown is balanced by one pyridinium cation, which forms the hydrogen bond with an adjacent solvent pyridine molecule. Magnetic measurements demonstrate antiferromagnetic coupling interactions and field-induced slow magnetic relaxation in complex 4.