Issue 41, 2011

Determination of the relevant magnetic interactions in low-dimensional molecular materials: the fundamental role of single crystal high frequency EPR

Abstract

A new one-dimensional copper(II) complex with formula [Cu(hfac)2(N3TEMPO)]n (hfac = hexafluoroacetylacetonate and N3TEMPO = 4-azido-2,2,6,6-tetramethylpiperidine-1-oxyl) has been synthesized and investigated by X-ray crystallography, magnetometry and multifrequency single crystal EPR. The system crystallizes in the P[1 with combining macron] space group with two non equivalent copper(II) ions in the unit cell, the two nitroxide radicals being coordinated to Cu(1) in axial positions. The copper(II) ions are bridged by N3TEMPO radicals resulting in a zig-zag chain structure. The magnetic susceptibility data were at first satisfactorily modeled assuming an alternating spin chain along the monodimensional covalent skeleton, with a ferromagnetic interaction between Cu(1) and the nitroxide moieties and a weaker antiferromagnetic interaction between these and Cu(2) (J1 = −13.8 cm−1, J2 = +2.4 cm−1). However, single crystal EPR studies performed at the X- and W-band clearly demonstrate that the observed magnetic monodimensional character of the complex is actually due to the intermolecular contacts involving N3TEMPO ligands. This prompted us to fit the magnetic data using a consistent model, pointing out the fundamental role of single crystal EPR data in defining a correct model to describe the magnetic properties of molecular low dimensional systems.

Graphical abstract: Determination of the relevant magnetic interactions in low-dimensional molecular materials: the fundamental role of single crystal high frequency EPR

Supplementary files

Article information

Article type
Paper
Submitted
28 Apr 2011
Accepted
24 Jun 2011
First published
23 Aug 2011

Dalton Trans., 2011,40, 10843-10850

Determination of the relevant magnetic interactions in low-dimensional molecular materials: the fundamental role of single crystal high frequency EPR

R. A. Allão, A. K. Jordão, J. A. L. C. Resende, A. C. Cunha, V. F. Ferreira, M. A. Novak, C. Sangregorio, L. Sorace and M. G. F. Vaz, Dalton Trans., 2011, 40, 10843 DOI: 10.1039/C1DT10780A

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