Large Magnetic Anisotropy in a Coupled Dinuclear FeII Field-Induced Single-Molecule Magnet

Abstract A series of [Me2indM(μ-Cl)(THF)]2 (M = Mn, Fe, Zn) dimers utilizing a novel bulky indoline ligand (Me2indH = 5-methoxy-2,2-dimethyl-3,3-diphenyl-7-diphenylmethylindoline) were synthesized and magnetically characterized. Analysis of the single crystal structure reveals that each of the complexes exhibits a distorted tetrahedral geometry around the metal center. Static magnetic measurements of 3-Fe demonstrate ferromagnetic coupling (J = 3.05 cm–1) between the Fe ions and an exceptionally high axial anisotropy (D = −33.8 cm–1). Theoretical investigations reveal that the magnetic anisotropy vectors of the two metal centers are largely aligned with the metal–metal axis, with the magnetic anisotropy vector of the two Fe atoms deviating by 29.24° from that axis. Dynamic magnetic measurements display out-of-phase behavior, indicating that 3-Fe acts as a field-induced single-molecule magnet with a Ueff of 43.7(5) cm–1.