Ab initio study of magnetic coupling in aniline-based molecules: Role of Fe atoms

Abstract

Our interest is the study of magnetic properties of organic compounds. We have previously reported a new class of organic magnets based on aniline and aminonaphthalenesulfonic acid. In this work, we explore theoretically a simple model based on superposed aniline molecules (radicals) and Fe atoms to determine the mechanism that stabilizes the parallel alignment of the electronic spin. Calculations were performed within the non-local spin density approximation with Becke's exchange functional and the gradient-corrected functional of Lee, Yang and Parr (BYLP) using the DMol program. The results show a high sensitivity of the magnetic properties to the oxidation state of the metal: intercalated between molecular aniline the total spins are 1, 0 and 1/2 for Fe0, FeII and FeIII, and between radicals the spins are 0, 0 and 1/2, respectively. This opens the possibility of creating molecular magnets by doping purely organic materials with transition metal atoms or ions.