A First-Principles Analysis of the Magnetism of CuII Polynuclear Coordination Complexes: the Case of [Cu₄(bpy)₄(aspartate)₂(H₂O)₃](ClO₄)₄·2.5H₂O

摘要

The magnetic structure of the [Cu₄(bpy)₄(aspartate)₂(H₂O)₃](ClO₄)₄·2.5 H₂O crystal — using fractional coordinates determined at room-temperature — has been analysed in detail. This analysis has been carried out by extending our first principles bottom-up theoretical approach, which was initially designed to study through-space magnetic interactions, to handle through-bond magnetic interactions. The only input data required by this approach are the values of the computed J_AB exchange parameters for all the unique pairs of spin-containing centres. The results allow the magnetic structure of the crystal, which presents two types of isolated tetranuclear CuII clusters, to be defined in quantitative terms. Each of these clusters presents ferro and antiferromagnetic interactions, the former being stronger, although outnumbered by the latter. The computed magnetic susceptibility curve shows the same qualitative features as the experimental data. However, there are small differences that are presumed to be associated with the use of room-temperature crystal coordinates.