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

Rezende dos Santos, Leonardo Humberto; Lanza, Arianna; Barton, Alyssa M.; Brambleby, Jamie; Blackmore, William J. A.; Goddard, Paul A.; Xiao, Fan; Williams, Robert C.; Lancaster, Tom; Pratt, Francis L.; Blundell, Stephen J.; Singleton, John; Manson, Jamie L.; Macchi, Piero (2016). Experimental and Theoretical Electron Density Analysis of Copper Pyrazine Nitrate Quasi-Low-Dimensional Quantum Magnets. Journal of the American Chemical Society, 138(7), pp. 2280-2291. American Chemical Society 10.1021/jacs.5b12817

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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 antiferromagnetic coupling can be quantitatively explained by the Cu-Cu superexchange 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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Rezende dos Santos, Leonardo Humberto; Lanza, Arianna and Macchi, Piero

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0002-7863

Publisher:

American Chemical Society

Funders:

[4] Swiss National Science Foundation

Language:

English

Submitter:

Piero Macchi

Date Deposited:

06 Apr 2016 11:30

Last Modified:

07 Apr 2016 23:14

Publisher DOI:

10.1021/jacs.5b12817

PubMed ID:

26811927

BORIS DOI:

10.7892/boris.78906

URI:

https://boris.unibe.ch/id/eprint/78906

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