Synthesis, crystal structure, and magnetic properties of a very rare double μ-1,1-Azido- and a μ-1,1-(OMe)-Bridged Fe^III dimer containing a N,N,O-donor tridentate Schiff base ligand

Abstract

Two new Fe^III complexes, [Fe₂L₂ (μ-OMe) ₂ (NCS) ₂] (1) and [Fe₂L₂ (μ-N₃)₂ (N₃)₂] (2), have been synthesized using a N,N,O-donor tridentate Schiff base ligand HL {2-[(2-dimethylaminoethylimino)methyl]phenol}, the condensation product of salicylaldehyde and N,N-dimethyl-1,2-diaminoethane. The complexes were characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Both crystal structures are centrosymmetric dimers containing two Fe_III atoms, which are bridged in compound 1 by two methoxy anions and in compound 2 by two μ-1,1-azides. The chelating tridentate Schiff base and a terminal thiocyanato (for 1) or azido (for 2) group complete the hexacoordination of the distorted octahedral environment of each iron center. The magnetic properties of compound 1 show the presence of antiferromagnetic exchange interactions mediated by double methoxy bridges (J = –29.45 cm^–1). Compound 2 shows the presence of very weak ferromagnetic exchange interactions mediated by double μ-1,1-N₃ bridges (J = 1.08 cm^–1)