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.

doi:10.1021/jacs.5b12817

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.

Authors

L.H.R. Dos Santos

A Lanza

A.M. Barton

J. Brambleby

P.A. Goddard

F. Xiao

R.C. Williams

Professor Tom Lancaster tom.lancaster@durham.ac.uk
Professor

F.L. Pratt

S.J. Blundell

J. Singleton

J.L. Manson

P. Macchi

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

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Copyright Statement
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/jacs.5b12817.