Electronic structure and magnetic anisotropy of the [Co_4(hmp)_4(CH_3OH)_4Cl_4] molecule

TL;DR

This study uses density-functional calculations to analyze the electronic structure and magnetic anisotropy of a cobalt-based molecular magnet, revealing how geometric variations influence magnetic properties.

Contribution

It identifies multiple low-energy isomers and demonstrates the dependence of magnetic anisotropy on molecular geometry and protonation states.

Findings

Magnetic anisotropy varies with pyridine-pyridine separation.

Different isomers exhibit easy axis, easy plane, and triaxial magnetic behavior.

Protonation state affects the magnetic properties.

Abstract

Accurate density-functional based calculations have been performed on the Co_4(hmp)_4(CH_3OH)_4Cl_4 molecular magnet where hmp is deprotonated hydroxymethyl pyridine. In addition to the experimentally observed staggered geometry, we identify two isomers, referred to as eclipsed and half-staggered/half-eclipsed, that are reasonably low in energy. Our calculations show that the magnetic anisotropy is strongly dependent on the pyridine-pyridine separation and that the three structures exhibit easy axis, easy plane and triaxial behavior. Other effects such as partial reprotonation of the hmp is considered.