A theoretical analysis of the magnetic properties of the low dimensional bis(2-chloropyrazine)dichlorocopper(II) molecule-based magnet

The First-principles Bottom-up (FPBU) theoretical procedure is applied to rationalize the different macroscopic magnetic properties of the bis(2-chloropyrazine)dichlorocopper(II), Cu(2-Clpz)2Cl2, crystal. It is found that this crystal presents three non-negligible antiferromagnetic through-space interactions: J(d1) = −7.53 cm−1, J(d3) = −0.15 cm−1, and J(d4) = −1.47 cm−1. The two strongest magnetic couplings generate a magnetic topology of alternating 2D layers, which are then weakly interconnected by J(d3): a quasi-2D magnetic topology. The computed magnetic susceptibility curves using a model space for the real quasi-2D, and both enforced 2D and 1D magnetic topologies (obtained by deleting J(d3) and J(d3) and J(d4), respectively, from the computed magnetic topology) are close and similar to the experimental curve. This similarity explains why the experimental magnetic susceptibility curve of the Cu(2-Clpz)2Cl2 crystal could be fitted by a 1D model. Heat capacity and magnetization simulations provide unequivocal signatures of magnetic dimensionality. Finally, comparison among five bis(substituted − pyrazine or pyridine) dichlorocopper(II) coordination complexes will enable us to draw qualitative conclusions about the relationship between substituent positions and magnetic dimensionality.

Graphical abstractA First-principles Bottom-up study of Cu(2-Clpz)2Cl2 shows that it presents a quasi-2D magnetic topology consisting of a set of very weakly interacting AFM layers (−7.5 and −1.5 cm−1). Heat capacity Cp(T) and magnetization M(H) simulations provide unequivocal signatures of magnetic dimensionality, unlike magnetic susceptibility χ(T) computed data. Comparison among five Cu(substituted-pz/py)2Cl2 coordination complexes will enable us to draw qualitative conclusions about the relationship between substituent positions and magnetic dimensionality.Figure optionsDownload full-size imageDownload as PowerPoint slide