Experimental and Theoretical Electron Density Analysis of Copper Pyrazine Nitrate Quasi-Low-Dimensional Quantum Magnets

Dos Santos, L.H.R.; Lanza, A; Barton, A.M.; Brambleby, J.; Goddard, P.A.; Xiao, F.; Williams, R.C.; Lancaster, T.; Pratt, F.L.; Blundell, S.J.; Singleton, J.; Manson, J.L.; Macchi, P.

Abstract

The accurate electron density distribution and magnetic properties of two metal-organic polymeric magnets, the quasi-one-dimensional (1D) Cu(pyz)(NO3)2 and the quasi-two-dimensional (2D) [Cu(pyz)2(NO3)]NO3·H2O, have been investigated by high-resolution single-crystal X-ray diffraction and Density Functional Theory calculations on the whole periodic systems and on selected fragments. Topological analyses, based on Quantum Theory of Atoms in Molecules, enabled the characterization of possible magnetic exchange pathways and the establishment of relationships between the electron (charge and spin) densities and the exchange-coupling constants. In both compounds, the experimentally observed anti-ferromagnetic coupling can be quantitatively explained by the Cu-Cu super-exchange pathway mediated by the pyrazine bridging ligands, via a σ-type interaction. From topological analyses of experimental charge-density data, we show for the first time that the pyrazine tilt angle does not play a role in determining the strength of the magnetic interaction. Taken in combination with molecular orbital analysis and spin density calculations, we find a synergistic relationship between spin delocalization and spin polarization mechanisms and that both determine the bulk magnetic behavior of these Cu(II)-pyz coordination polymers.

Citation

Dos Santos, L., Lanza, A., Barton, A., Brambleby, J., Goddard, P., Xiao, F., …Macchi, P. (2016). Experimental and Theoretical Electron Density Analysis of Copper Pyrazine Nitrate Quasi-Low-Dimensional Quantum Magnets. Journal of the American Chemical Society, 138(7), 2280-2291. https://doi.org/10.1021/jacs.5b12817

• Journal Article Type: Article
• Acceptance Date: Jan 26, 2016
• Online Publication Date: Jan 26, 2016
• Publication Date: Feb 24, 2016
• Deposit Date: Feb 1, 2016
• Publicly Available Date: Jan 26, 2017
• Journal: Journal of the American Chemical Society
• Print ISSN: 0002-7863
• Electronic ISSN: 1520-5126
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 138
• Issue: 7
• Pages: 2280-2291
• DOI: https://doi.org/10.1021/jacs.5b12817
• Public URL: https://durham-repository.worktribe.com/output/1393546