A Neutral Fe₄^tBuL₄ All Ferric Grid Complex: Structural and Variable Temperature Magnetic Properties

Abstract

A neutral all ferric [2×2] grid complex Fe4tBuL4 1 was synthesized and characterized in the solid‐state by X‐ray crystallography, variable temperature magnetic susceptibility and Mössbauer spectroscopy. The absence of any coordinate bond or other structural changes between 90(2) and 320(2) K indicated no changes to the electronic structure of 1 occurred in the solid‐state over this temperature range. Variable temperature magnetic susceptibility data were fitted to an isotropic spin Hamiltonian model and suggested weak antiferromagnetic exchange coupling between the high‐spin ferric ions (J = –16.1 cm‐1). Mössbauer spectroscopy parameters (δ = 0.416(9) mm s–1 & ΔEQ = 0.87(7) mm s‐1), powder EPR spectra, and broken symmetry density functional theory calculations supported the high‐spin ferric oxidation state assignment.