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Title: Experimental and theoretical characterization of the magnetic properties of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) : a two-dimensional quantum magnet arising from super-superexchange interactions through hydrogen bonded paths.

Abstract

The structural, electronic, and magnetic properties of the new linear chain coordination polymer CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) were determined by single crystal X-ray diffraction at various temperatures, SQUID magnetometry, pulsed-field magnetization, ESR, muon-spin relaxation ({mu}SR), and electronic structure calculations. Each Cu{sup 2+} ion of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) is located at a distorted CuF{sub 2}O{sub 2}N{sub 2} octahedron with axial elongation along the Cu?N bonds. These octahedra are tethered together by strong F...H-O hydrogen bonds to yield two-dimensional (2D) square nets in the bc-plane that are linked along the a-direction by pyrazine linkages. Measurements of the g-factor by ESR along with first principles density functional theory electronic structure calculations show that the magnetic orbital of the Cu{sup 2+} ion lies in the CuF{sub 2}O{sub 2} plane thus forming a 2D antiferromagnetic square lattice. A broad maximum observed in x(T) at 10 K indicates a modest spin exchange interaction through the Cu-F...H-O-Cu supersuperexchange paths, and a theoretical fit of x(T) to a 2D square model gives J{sub 2D}/k{sub B} = ?5.58(1) K (in the convention where J rather than 2J is used for spin exchange). At lower temperatures, x(T) shows a sharp peak at 2.6 K, which signalsmore » a transition to a long-range magnetic ordering as confirmed by coherent precession of implanted muons. Isothermal M(B) measurements made at 0.5 K on an aligned single crystal reveal magnetic saturation, M{sub sat}, at 28.8 T (B{sub {parallel}}a) while a higher field of 33.1 T is required to saturate the spins when B is applied perpendicular to the a-axis thus showing clear anisotropy in these orientations. The presence of strong hydrogen bonds in CuF{sub 2}(H{sub 2}O){sub 2}(pyz) causes the chains to adopt a tilted packing arrangement, thus leading to a novel ground-state likely characterized by spin-canting within the 2D layers and a markedly increased critical temperature relative to the well-known Cu(NO{sub 3}){sub 2}(pyz) polymer chain compound.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Royal Commission; Engineering and Physical Sciences Research Council (EPSRC)
OSTI Identifier:
961716
Report Number(s):
ANL/MSD/JA-61851
Journal ID: ISSN 0002-7863; JACSAT; TRN: US200923%%247
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc.
Additional Journal Information:
Journal Volume: 20; Journal Issue: 24 ; Nov. 24, 2008; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; ANISOTROPY; CRITICAL TEMPERATURE; ELECTRONIC STRUCTURE; ELONGATION; FUNCTIONALS; HYDROGEN; MAGNETIC PROPERTIES; MAGNETIZATION; MAGNETS; MONOCRYSTALS; MUON SPIN RELAXATION; MUONS; POLYMERS; PYRAZINES; SATURATION; SPIN; SPIN EXCHANGE; X-RAY DIFFRACTION

Citation Formats

Manson, J L, Conner, M C, McConnell, A C, Southerland, H I, Schlueter, J A, Malfant, I, Lancaster, T, Blundell, S J, Brooks, M L, Pratt, F L, Singleton, J, McDonald, R D, Lee, C, Whangbo, M -H, Eastern Washington Univ., Univ. Paul Sabatier, Oxford Univ., Rutherford Appleton Lab., LANL,, and North Carolina State Univ. Experimental and theoretical characterization of the magnetic properties of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) : a two-dimensional quantum magnet arising from super-superexchange interactions through hydrogen bonded paths.. United States: N. p., 2008. Web. doi:10.1021/cm8016566.
Manson, J L, Conner, M C, McConnell, A C, Southerland, H I, Schlueter, J A, Malfant, I, Lancaster, T, Blundell, S J, Brooks, M L, Pratt, F L, Singleton, J, McDonald, R D, Lee, C, Whangbo, M -H, Eastern Washington Univ., Univ. Paul Sabatier, Oxford Univ., Rutherford Appleton Lab., LANL,, & North Carolina State Univ. Experimental and theoretical characterization of the magnetic properties of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) : a two-dimensional quantum magnet arising from super-superexchange interactions through hydrogen bonded paths.. United States. https://doi.org/10.1021/cm8016566
Manson, J L, Conner, M C, McConnell, A C, Southerland, H I, Schlueter, J A, Malfant, I, Lancaster, T, Blundell, S J, Brooks, M L, Pratt, F L, Singleton, J, McDonald, R D, Lee, C, Whangbo, M -H, Eastern Washington Univ., Univ. Paul Sabatier, Oxford Univ., Rutherford Appleton Lab., LANL,, and North Carolina State Univ. Mon . "Experimental and theoretical characterization of the magnetic properties of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) : a two-dimensional quantum magnet arising from super-superexchange interactions through hydrogen bonded paths.". United States. https://doi.org/10.1021/cm8016566.
@article{osti_961716,
title = {Experimental and theoretical characterization of the magnetic properties of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) : a two-dimensional quantum magnet arising from super-superexchange interactions through hydrogen bonded paths.},
author = {Manson, J L and Conner, M C and McConnell, A C and Southerland, H I and Schlueter, J A and Malfant, I and Lancaster, T and Blundell, S J and Brooks, M L and Pratt, F L and Singleton, J and McDonald, R D and Lee, C and Whangbo, M -H and Eastern Washington Univ. and Univ. Paul Sabatier and Oxford Univ. and Rutherford Appleton Lab. and LANL, and North Carolina State Univ.},
abstractNote = {The structural, electronic, and magnetic properties of the new linear chain coordination polymer CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) were determined by single crystal X-ray diffraction at various temperatures, SQUID magnetometry, pulsed-field magnetization, ESR, muon-spin relaxation ({mu}SR), and electronic structure calculations. Each Cu{sup 2+} ion of CuF{sub 2}(H{sub 2}O){sub 2}(pyz) is located at a distorted CuF{sub 2}O{sub 2}N{sub 2} octahedron with axial elongation along the Cu?N bonds. These octahedra are tethered together by strong F...H-O hydrogen bonds to yield two-dimensional (2D) square nets in the bc-plane that are linked along the a-direction by pyrazine linkages. Measurements of the g-factor by ESR along with first principles density functional theory electronic structure calculations show that the magnetic orbital of the Cu{sup 2+} ion lies in the CuF{sub 2}O{sub 2} plane thus forming a 2D antiferromagnetic square lattice. A broad maximum observed in x(T) at 10 K indicates a modest spin exchange interaction through the Cu-F...H-O-Cu supersuperexchange paths, and a theoretical fit of x(T) to a 2D square model gives J{sub 2D}/k{sub B} = ?5.58(1) K (in the convention where J rather than 2J is used for spin exchange). At lower temperatures, x(T) shows a sharp peak at 2.6 K, which signals a transition to a long-range magnetic ordering as confirmed by coherent precession of implanted muons. Isothermal M(B) measurements made at 0.5 K on an aligned single crystal reveal magnetic saturation, M{sub sat}, at 28.8 T (B{sub {parallel}}a) while a higher field of 33.1 T is required to saturate the spins when B is applied perpendicular to the a-axis thus showing clear anisotropy in these orientations. The presence of strong hydrogen bonds in CuF{sub 2}(H{sub 2}O){sub 2}(pyz) causes the chains to adopt a tilted packing arrangement, thus leading to a novel ground-state likely characterized by spin-canting within the 2D layers and a markedly increased critical temperature relative to the well-known Cu(NO{sub 3}){sub 2}(pyz) polymer chain compound.},
doi = {10.1021/cm8016566},
url = {https://www.osti.gov/biblio/961716}, journal = {J. Am. Chem. Soc.},
issn = {0002-7863},
number = 24 ; Nov. 24, 2008,
volume = 20,
place = {United States},
year = {2008},
month = {11}
}