Effect of ligand substitution on the exchange interactions in {Mn12}-type single-molecule magnets

TL;DR

This study explores how ligand substitution influences intra-molecular spin exchange interactions in Mn12-type single-molecule magnets, revealing a correlation between ligand electronegativity and exchange energies through electronic structure analysis.

Contribution

It introduces a simple scheme based on accumulated Pauling electronegativity numbers to predict changes in exchange interactions due to ligand substitution in Mn12 molecules.

Findings

Exchange interactions vary with ligand electronegativity.

A correlation exists between ligand electronegativity and exchange energies.

Electronic structure calculations confirm the proposed scheme.

Abstract

We investigate how the ligand substitution affects the intra-molecular spin exchange interactions, studying a prototypal family of single-molecule magnets comprising dodecanuclear cluster molecules [Mn12O12(COOR)16]. We identify a simple scheme based on accumulated Pauling electronegativity numbers (a.e.n.) of the carboxylate ligand groups (R). The redistribution of the electron density, controlled by a.e.n. of a ligand, changes the degree of hybridization between 3d electrons of manganese and 2p electrons of oxygen atoms, thus changing the exchange interactions. This scheme, despite its conceptual simplicity, provides a strong correlation with the exchange energies associated with carboxylate bridges, and is confirmed by the electronic structure calculations taking into account the Coulomb correlations in magnetic molecules.