Rectangular two-dimensional antiferromagnetic systems: Analysis of copper(II) pyrazine dibromide and dichloride

Butcher, Robert T.; Landee, Christopher P.; Fan, Xing

doi:10.1016/j.ica.2008.03.090

Cited by 36 publications

(33 citation statements)

References 27 publications

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“…Single crystals (dark plates) were grown through recrystallization of the prisms from acetonitrile. CHN Calcd (found) for C 10 (3). CuCl 2 (0.0660 g, 0.491 mM) in 2 mL of water was added to 2-amino-5-chloro-3-fluoropyridine (0.1496 g, 1.02 mM) in 1.7 mL of 6 M HCl, yielding a clear, forest-green solution, which was left to evaporate at room temperature.…”

Section: Synthesismentioning

confidence: 99%

“…Synthesis and studies of the structures and corresponding magnetic exchange properties of copper(II) halide coordination complexes and salts have been of interest to our research group for quite some time [1][2][3][4]. These systems merit study due to the low-dimensional anti-ferromagnetic exchange observed and the opportunity to compare and contrast packing motifs to gain insight into magneto-structural correlations.…”

Section: Introductionmentioning

confidence: 99%

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Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Solomon

Landee

Turnbull

et al. 2014

Journal of Coordination Chemistry

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Using 2-amino-5-chloro-3-fluoropyridine, two new copper halide coordination complexes and two new salts have been synthesized: [(3,5-FCAP) 2 CuCl 2 ] (1), [(3,5-FCAP) 2 CuBr 2 ](2), (3,5-FCAPH) 2 (3) and (3,5-FCAPH) 2 [CuBr 4 ] (4) [3,5-FCAP = 2-amino-5-chloro-3-fluoropyridine; 3,5-FCAPH = 2-amino-5-chloro-3-fluoropyridinium]. These complexes have been analyzed throughThe reaction of 2-amino-5-chloro-3-fluoropyridine (3,5-FCAP) with copper(II) halides in neutral or acidic media gave the complexes (3,5-FCAP) 2 CuX 2 and (3,5-FCAPH) 2 CuX 4 (X = Cl, Br). Variable temperature magnetic susceptibility reveals anti-ferromagnetic interactions, J, ranging from −0.9 to −31.3 K.single-crystal X-ray diffraction and temperature-dependent magnetic susceptibility. Compounds 1 and 2 crystallize in the triclinic space group P-1, while 3 and 4 crystallize in the monoclinic space group P2 1 /c. All structures were distinct, with 1 giving a bihalide bridged chain, 2 yielding a halide bridged dimer, 3 forming a two-halide bridged chain via short Cl⋅⋅⋅Cl contacts, and 4 producing a rectangular sheet via short Br⋅⋅⋅Br contacts. All four compounds exhibit anti-ferromagnetic interactions and were fit to linear chain (1 and 3), dimer (2), and rectangular 2-D sheet (4) models. The resulting J/k B values are −3.4(1), −31.3(8), −0.9(1), and −9.46(6) K with an α value (α = Jʹ/J) of 0.06(2), respectively.

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Section: Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Solomon

Landee

Turnbull

et al. 2014

Journal of Coordination Chemistry

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“…An added advantage of molecular systems is the ability to make controlled adjustments to the crystal structure, thereby tuning interaction strengths and better testing the predictions of the SLHAFM and associated models. To this end, we and others have previously shown that it is possible to gain a degree of control over the primary exchange energy in low-dimensional molecular antiferromagnets via constitutional changes that include deuteration 18 , anion substitution 11,19 , exchange of halide ligands 20,21 , and the application of high pressures 22,23 .…”

Section: Introductionmentioning

confidence: 99%

Control of the third dimension in copper-based square-lattice antiferromagnets

et al. 2016

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Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF2)(pyz)2]ClO4 [pyz = pyrazine], [CuL2(pyz)2](ClO4)2 [L = pyO = pyridine-N-oxide and 4-phpyO = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz)2] 2+ nearly square layers, but exhibit interlayer spacings that vary from 6.5713Å to 16.777Å, as dictated by the axial ligands. We present the structural and magnetic properties of this family as determined via x-ray diffraction, electron-spin resonance, pulsed-and quasistatic-field magnetometry and muon-spin rotation, and compare them to those of the prototypical two-dimensional magnetic polymer Cu(pyz)2(ClO4)2. We find that, within the limits of the experimental error, the two-dimensional, intralayer exchange coupling in our family of materials remains largely unaffected by the axial ligand substitution, while the observed magnetic ordering temperature (1.91 K for the material with the HF2 axial ligand, 1.70 K for the pyO and 1.63 K for the 4-phpyO) decreases slowly with increasing layer separation. Despite the structural motifs common to this family and Cu(pyz)2(ClO4)2, the latter has significantly stronger two-dimensional exchange interactions and hence a higher ordering temperature. We discuss these results, as well as the mechanisms that might drive the long-range order in these materials, in terms of departures from the ideal S = 1/2 two-dimensional square-lattice Heisenberg antiferromagnet. In particular, we find that both spin exchange anisotropy in the intralayer interaction and interlayer couplings (exchange, dipolar, or both) are needed to account for the observed ordering temperatures, with the intralayer anisotropy becoming more important as the layers are pulled further apart.

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“…To this end, a series of coordination polymers based on Cu(II) ions bridged by pyrazine (C 4 H 4 N 2 ) molecules have proven to be highly versatile. In these systems it has been shown that it is possible to alter significantly the primary exchange energies via adjustment of the ligands [17] and the counterions [18, S9], or fine-tune the exchange by a few percent via isotopic substitution [20], all the while maintaining the same basic metal-pyrazine network. In this paper we demonstrate the power of this strategy by chemically engineering a reduction in the dimensionality of a magnetic system.…”

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confidence: 99%

Dimensionality Selection in a Molecule-Based Magnet

et al. 2012

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Gaining control of the building blocks of magnetic materials and thereby achieving particular characteristics will make possible the design and growth of bespoke magnetic devices. While progress in the synthesis of molecular materials, and especially coordination polymers, represents a significant step towards this goal, the ability to tune the magnetic interactions within a particular framework remains in its infancy. Here we demonstrate a chemical method which achieves dimensionality selection via preferential inhibition of the magnetic exchange in an S = 1/2 antiferromagnet along one crystal direction, switching the system from being quasi-two-to quasi-one-dimensional while effectively maintaining the nearest-neighbour coupling strength.Coordination polymers are self-organising materials consisting of arrays of metal ions linked via molecular ligands, with non-coordinated counterions supplying charge neutrality. The choice of initial components permits a high level of control over the final product, enabling many different polymeric architectures to be obtained [1]. These materials provide a route to successful crystal engineering, and a number of functionalities are being actively studied, including gas storage [2-4], optoelectronic [5,6], ferroelectric [7,8] and magnetic properties [9-14].Although it is now possible to generate an assortment of disparate magnetic lattices using this method [15,16], true control of magnetic exchange interactions implies an ability to adjust selected parameters while keeping others constant. To this end, a series of coordination polymers based on Cu(II) ions bridged by pyrazine (C 4 H 4 N 2 ) molecules have proven to be highly versatile. In these systems it has been shown that it is possible to alter significantly the primary exchange energies via adjustment of the ligands [17] and the counterions [18, S9], or fine-tune the exchange by a few percent via isotopic substitution [20], all the while maintaining the same basic metal-pyrazine network. In this paper we demonstrate the power of this strategy by chemically engineering a reduction in the dimensionality of a magnetic system. After first designing a material based on coordinated planes of Cu(II), we adapt the recipe such that the ligand bridges are broken along a specific crystal direction, resulting in a chain-like compound. Because the ligand mediating the magnetic interactions in both cases is unchanged, the nearest-neighbour exchange energies of the two materials are found to be equal to each other to within 5%. The difference in numbers of nearest-neighbours, however, means that the strength of the combined exchange interactions acting on each magnetic ion in the quasitwo-dimensional material is twice that of its quasi-onedimensional cousin.Figs. 1(a) and (b) show the crystal structure of orthorhombic [Cu(pyz) 2 (pyO) 2 ](PF 6 ) 2 (where pyz = pyrazine and pyO = pyridine-N -oxide, C 5 H 5 NO) determined using single-crystal x-ray diffraction [21]. S = 1/2 Cu ions are linked by pyz molecules into nearly square planar ...

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Rectangular two-dimensional antiferromagnetic systems: Analysis of copper(II) pyrazine dibromide and dichloride

Cited by 36 publications

References 27 publications

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Control of the third dimension in copper-based square-lattice antiferromagnets

Dimensionality Selection in a Molecule-Based Magnet

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Rectangular two-dimensional antiferromagnetic systems: Analysis of copper(II) pyrazine dibromide and dichloride

Cited by 36 publications

References 27 publications

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)2CuX2 and (3,5-FCAPH)2CuX4

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)2CuX2 and (3,5-FCAPH)2CuX4

Control of the third dimension in copper-based square-lattice antiferromagnets

Dimensionality Selection in a Molecule-Based Magnet

Contact Info

Product

Resources

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Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄