DFT broken-symmetry exchange couplings calculation in a 1D chain of bridged iron basic carboxylates

Abstract

DFT broken-symmetry calculations at the B3LYP level were carried out to evaluate the exchange coupling constants defined by the Heisenberg-Dirac-van Vleck spin Hamiltonian (HDvV), Ĥ = -2JŜaŜb, in a 1D chain of iron basic carboxylate cores [Fe3O(Piv)6(H2O)] bridged by dicyanamide, and two related trinuclear Fe3O moieties. The chain complex was modeled as two Fe3O units that preserve all features of the repetitive unit in the infinite real system. All geometries were taken from the crystallographic data previously reported. The obtained calculated values for the J constants are in good agreement with experimental results. The weak anti-ferromagnetic inter-Fe3O core interaction along the chain is also reasonably accounted by the calculations. This methodology appears as a useful tool in the theoretical evaluation of exchange coupling constants in 1D systems.