A Combined Experimental and Theoretical Study on Bis(μ‐alkoxo)diiron(III) Complexes with Hydroxybenzylaminoethanol [O,N,O] Donor Ligands: Syntheses, Structures and Magnetic Properties

Abstract

AbstractThree new neutral bis(μ‐alkoxo)diiron(III) complexes were prepared from N(R),N‐(2‐methylene‐4,6‐di‐tert‐butylphenol)aminoethan‐1‐ol ligands (H2L1, R = Me and H2L2, R = H). In these complexes, the ligand wraps around the metal center exhibiting a tridentate facial coordination mode with alkoxo‐bridging oxygen, amine nitrogen and phenoxo oxygen donor atoms. In the complex [Fe(acac)L1]2·MeCN (1) acetylacetonato coligand complete the distorted octahedral coordination spheres of the iron(III) ions, whereas in the five‐coordinate iron(III) chloride complexes [FeClL1]2 (2) and [FeClL2]2 (3) the ligands induce a geometry that is intermediate between square pyramidal and trigonal bipyramidal. Magnetic studies carried out on these dinuclear complexes showed that J values vary from –16.1 to –29.6 cm–1. Both experimental and theoretical DFT studies address a strong magneto‐structural correlation between the exchange coupling constant and the Fe–O–Fe angle of the complexes. The crossover point from antiferromagnetic to ferromagnetic coupling is predicted to be 100.4° for this family of N(R),N‐(2‐methylene‐4,6‐di‐tert‐butylphenol)aminoethan‐1‐ol ligands.