1
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Wang Y, Fu P, Takatsu H, Tassel C, Hayashi N, Cao J, Bataille T, Koo HJ, Ouyang Z, Whangbo MH, Kageyama H, Lu H. Construction of Ideal One-Dimensional Spin Chains by Topochemical Dehydration/Rehydration Route. J Am Chem Soc 2024; 146:8320-8326. [PMID: 38489763 DOI: 10.1021/jacs.3c13902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
One-dimensional (1D) Heisenberg antiferromagnets are of great interest due to their intriguing quantum phenomena. However, the experimental realization of such systems with large spin S remains challenging because even weak interchain interactions induce long-range ordering. In this study, we present an ideal 1D S = 5/2 spin chain antiferromagnet achieved through a multistep topochemical route involving dehydration and rehydration. By desorbing three water molecules from (2,2'-bpy)FeF3(H2O)·2H2O (2,2'-bpy = 2,2'-bipyridyl) at 150 °C and then intercalating two water molecules at room temperature (giving (2,2'-bpy)FeF3·2H2O 1), the initially isolated FeF3ON2 octahedra combine to form corner-sharing FeF4N2 octahedral chains, which are effectively separated by organic and added water molecules. Mössbauer spectroscopy reveals significant dynamical fluctuations down to 2.7 K, despite the presence of strong intrachain interactions. Moreover, results from electron spin resonance (ESR) and heat capacity measurements indicate the absence of long-range order down to 0.5 K. This controlled topochemical dehydration/rehydration approach is further extended to (2,2'-bpy)CrF3·2H2O with S = 3/2 1D chains, thus opening the possibility of obtaining other low-dimensional spin lattices.
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Affiliation(s)
- Yanhong Wang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Peng Fu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hiroshi Takatsu
- Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan
| | - Cédric Tassel
- Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan
| | - Naoaki Hayashi
- Research Institute for Production Development, Shimogamo, Sakyo, Kyoto 606-0805, Japan
| | - Jiaojiao Cao
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Thierry Bataille
- Institut des Sciences Chimiques de Rennes UMR 6226 CNRS, UBL, Ecole Nationale Supérieure de Chimie de Rennes, 11, allée de Beaulieu, Rennes F-35708, France
| | - Hyun-Joo Koo
- Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Zhongwen Ouyang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Myung-Hwan Whangbo
- Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Hiroshi Kageyama
- Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan
| | - Hongcheng Lu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Huazhong University of Science and Technology, Wuhan 430074, China
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
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2
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Pitcairn J, Iliceto A, Cañadillas-Delgado L, Fabelo O, Liu C, Balz C, Weilhard A, Argent SP, Morris AJ, Cliffe MJ. Low-Dimensional Metal-Organic Magnets as a Route toward the S = 2 Haldane Phase. J Am Chem Soc 2023; 145:1783-1792. [PMID: 36626185 PMCID: PMC9881000 DOI: 10.1021/jacs.2c10916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Indexed: 01/11/2023]
Abstract
Metal-organic magnets (MOMs), modular magnetic materials where metal atoms are connected by organic linkers, are promising candidates for next-generation quantum technologies. MOMs readily form low-dimensional structures and so are ideal systems to realize physical examples of key quantum models, including the Haldane phase, where a topological excitation gap occurs in integer-spin antiferromagnetic (AFM) chains. Thus, far the Haldane phase has only been identified for S = 1, with S ≥ 2 still unrealized because the larger spin imposes more stringent requirements on the magnetic interactions. Here, we report the structure and magnetic properties of CrCl2(pym) (pym = pyrimidine), a new quasi-1D S = 2 AFM MOM. We show, using X-ray and neutron diffraction, bulk property measurements, density-functional theory calculations, and inelastic neutron spectroscopy (INS), that CrCl2(pym) consists of AFM CrCl2 spin chains (J1 = -1.13(4) meV) which are weakly ferromagnetically coupled through bridging pym (J2 = 0.10(2) meV), with easy-axis anisotropy (D = -0.15(3) meV). We find that, although small compared to J1, these additional interactions are sufficient to prevent observation of the Haldane phase in this material. Nevertheless, the proximity to the Haldane phase together with the modularity of MOMs suggests that layered Cr(II) MOMs are a promising family to search for the elusive S = 2 Haldane phase.
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Affiliation(s)
- Jem Pitcairn
- School
of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Andrea Iliceto
- School
of Metallurgy and Materials, University
of Birmingham, Elms Road,
Edgbaston, Birmingham B15
2TT, United Kingdom
| | | | - Oscar Fabelo
- Institut
Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble, France
| | - Cheng Liu
- Cavendish
Laboratory, Department of Physics, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Christian Balz
- ISIS
Neutron and Muon Source, STFC Rutherford
Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, United Kingdom
| | - Andreas Weilhard
- School
of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Stephen P. Argent
- School
of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Andrew J. Morris
- School
of Metallurgy and Materials, University
of Birmingham, Elms Road,
Edgbaston, Birmingham B15
2TT, United Kingdom
| | - Matthew J. Cliffe
- School
of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
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3
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From an antiferromagnetic insulator to a strongly correlated metal in square-lattice MCl 2(pyrazine) 2 coordination solids. Nat Commun 2022; 13:5766. [PMID: 36180432 PMCID: PMC9525593 DOI: 10.1038/s41467-022-33342-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/13/2022] [Indexed: 11/08/2022] Open
Abstract
Electronic synergy between metal ions and organic linkers is a key to engineering molecule-based materials with a high electrical conductivity and, ultimately, metallicity. To enhance conductivity in metal-organic solids, chemists aim to bring the electrochemical potentials of the constituent metal ions and bridging organic ligands closer in a quest to obtain metal-d and ligand-π admixed frontier bands. Herein, we demonstrate the critical role of the metal ion in tuning the electronic ground state of such materials. While VCl2(pyrazine)2 is an electrical insulator, TiCl2(pyrazine)2 displays the highest room-temperature electronic conductivity (5.3 S cm-1) for any metal-organic solid involving octahedrally coordinated metal ions. Notably, TiCl2(pyrazine)2 exhibits Pauli paramagnetism consistent with the specific heat, supporting the existence of a Fermi liquid state (i.e., a correlated metal). This result widens perspectives for designing molecule-based systems with strong metal-ligand covalency and electronic correlations.
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4
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Ishchenko AA, Pak AM, Nelyubina YV. Electron Density Distribution in the Crystal of the Biocompatible Metal–Organic Framework. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s107032842201002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Blackmore WJA, Curley SPM, Williams RC, Vaidya S, Singleton J, Birnbaum S, Ozarowski A, Schlueter JA, Chen YS, Gillon B, Goukassov A, Kibalin I, Villa DY, Villa JA, Manson JL, Goddard PA. Magneto-structural Correlations in Ni 2+-Halide···Halide-Ni 2+ Chains. Inorg Chem 2021; 61:141-153. [PMID: 34939800 PMCID: PMC8753652 DOI: 10.1021/acs.inorgchem.1c02483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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We present the magnetic
properties of a new family of S = 1 molecule-based
magnets, NiF2(3,5-lut)4·2H2O
and NiX2(3,5-lut)4, where
X = HF2, Cl, Br, or I (lut = lutidine C7H9N). Upon creation of isolated Ni–X···X–Ni
and Ni–F–H–F···F–H–F–Ni
chains separated by bulky and nonbridging lutidine ligands, the effect
that halogen substitution has on the magnetic properties of transition-metal-ion
complexes can be investigated directly and in isolation from competing
processes such as Jahn–Teller distortions. We find that substitution
of the larger halide ions turns on increasingly strong antiferromagnetic
interactions between adjacent Ni2+ ions via a novel through-space
two-halide exchange. In this process, the X···X bond
lengths in the Br and I materials are more than double the van der
Waals radius of X yet can still mediate significant magnetic interactions.
We also find that a simple model based on elongation/compression of
the Ni2+ octahedra cannot explain the observed single-ion
anisotropy in mixed-ligand compounds. We offer an alternative that
takes into account the difference in the electronegativity of axial
and equatorial ligands. The magnetic
properties of well-separated Ni2+ chains are highly dependent
on the bridging halide ligands. By increasing
the size of the halide ions, we can decrease the single-ion anisotropy
such that the system moves from easy plane to easy axis. Through-space
magnetic interactions between adjacent Ni2+ ions are also
turned on as the larger halides are substituted into the exchange
pathway.
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Affiliation(s)
- William J A Blackmore
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.,Department of Chemistry, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | | | | | - Shroya Vaidya
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - John Singleton
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Serena Birnbaum
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - John A Schlueter
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.,Division of Materials Research, National Science Foundation, Arlington, Virginia 22230, United States
| | - Yu-Sheng Chen
- ChemMatCARS, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Beatrice Gillon
- Laboratoire Leon Brillouin (LLB), CEA-CNRS, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Arsen Goukassov
- Laboratoire Leon Brillouin (LLB), CEA-CNRS, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Iurii Kibalin
- Laboratoire Leon Brillouin (LLB), CEA-CNRS, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Danielle Y Villa
- Department of Chemistry and Biochemistry, Eastern Washington State University, 226 Science, Cheney, Washington 99004, United States
| | - Jacqueline A Villa
- Department of Chemistry and Biochemistry, Eastern Washington State University, 226 Science, Cheney, Washington 99004, United States
| | - Jamie L Manson
- Department of Chemistry and Biochemistry, Eastern Washington State University, 226 Science, Cheney, Washington 99004, United States
| | - Paul A Goddard
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
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6
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Kenny EP, Jacko AC, Powell BJ. Tight-Binding Approach to Pyrazine-Mediated Superexchange in Copper-Pyrazine Antiferromagnets. Inorg Chem 2021; 60:11907-11914. [PMID: 34310131 DOI: 10.1021/acs.inorgchem.1c00532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigate the cause of spatial superexchange anisotropy in a family of copper-based, quasi-two-dimensional materials with very similar geometries. The compounds in this family differ mainly in their inter-layer separation but they have very different magnetic interactions, even within the basal plane. We use density functional theory and Wannier functions to parameterize two complimentary tight-binding models and show that the superexchange between the Cu2+ ions is dominated by a σ-mediated interaction between hybrid Cu-pyrazine orbitals centered on the copper atoms. We find no correlations between the strength of this exchange interaction and homologous geometric features across the compounds, such as Cu and pyrazine bond lengths and orientations of nearby counterions. We find that the pyrazine tilt angles do not affect the Cu-pyrazine-Cu exchange because the lowest unoccupied molecular orbital on pyrazine is at a very high energy (relative to the frontier orbitals, which are Cu-based). We conclude that careful control of the entire crystal structure, including non-homologous geometric features such as the inter-layer organic ligands, is vital for engineering magnetic properties.
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Affiliation(s)
- E P Kenny
- School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - A C Jacko
- School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - B J Powell
- School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia
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7
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Pineda NR, Piquini PC. Using topological analysis of the electron density to study a geometry-electronic structure relationship in M (d5–10)…O and E…O (E = Se,Te) compounds. COMPUT THEOR CHEM 2021. [DOI: 10.1016/j.comptc.2021.113279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Kirkman-Davis E, Witkos FE, Selmani V, Monroe JC, Landee CP, Turnbull MM, Dawe LN, Polson MIJ, Wikaira JL. Pyrazine-bridged Cu(ii) chains: diaquabis(n-methyl-2-pyridone)copper(ii) perchlorate complexes. Dalton Trans 2020; 49:13693-13703. [PMID: 32996511 DOI: 10.1039/d0dt02716b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A family of pyrazine-bridged, linear chain complexes of Cu(ii) of the formula [CuL2(H2O)2(pz)](ClO4)2 [pz = pyrazine; L = n-methyl-2(1H)-pyridone, n = 3 (1), 5 (2), and 6 (3)] has been prepared. Single-crystal X-ray diffraction shows six-coordinate, pyrazine-bridged chains with trans-pairs of ancillary ligands. The substituted pyridine molecules exist in their pyridone tautomers and are coordinated through the carbonyl oxygen atom. The structure is stabilized by intramolecular hydrogen bonds between the pyridone and water molecule, and via hydrogen bonds between the water molecules and perchlorate ions. 2 undergoes a crystallographic phase transition between C2/c (high temperature phase) and P1[combining macron] (low temperature phase). Powder EPR spectra reveal that all complexes are rhombic, although differences between gx and gy can only be seen clearly at Q-band. Variable temperature magnetic susceptibility data show antiferromagnetic interactions and the data were fit to the uniform chain model yielding J/kB = -9.8, -9.2 and -11 K for 1-3 respectively. Attempts to model an interchain interaction strength indicate that the chains are very well isolated.
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Affiliation(s)
- Emma Kirkman-Davis
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA.
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9
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Bruno G, Macetti G, Lo Presti L, Gatti C. Spin Density Topology. Molecules 2020; 25:molecules25153537. [PMID: 32748885 PMCID: PMC7436107 DOI: 10.3390/molecules25153537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/30/2020] [Accepted: 08/01/2020] [Indexed: 11/16/2022] Open
Abstract
Despite its role in spin density functional theory and it being the basic observable for describing and understanding magnetic phenomena, few studies have appeared on the electron spin density subtleties thus far. A systematic full topological analysis of this function is lacking, seemingly in contrast to the blossoming in the last 20 years of many studies on the topological features of other scalar fields of chemical interest. We aim to fill this gap by unveiling the kind of information hidden in the spin density distribution that only its topology can disclose. The significance of the spin density critical points, the 18 different ways in which they can be realized and the peculiar topological constraints on their number and kind, arising from the presence of positive and negative spin density regions, is addressed. The notion of molecular spin graphs, spin maxima (minima) joining paths, spin basins and of their valence is introduced. We show that two kinds of structures are associated with a spin-polarized molecule: the usual one, defined through the electron density gradient, and the magnetic structure, defined through the spin density gradient and composed in general by at least two independent spin graphs, related to spin density maxima and minima. Several descriptors, such as the spin polarization index, are introduced to characterize the properties of spin density critical points and basins. The study on the general features of the spin density topology is followed by the specific example of the water molecule in the 3B1 triplet state, using spin density distributions of increasing accuracy.
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Affiliation(s)
- Giovanna Bruno
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy; (G.B.); (L.L.P.)
| | - Giovanni Macetti
- Laboratoire de Physique et Chimie Théoriques (LPCT), Université de Lorraine & CNRS, 1 Boulevard Arago, F–57078 Metz, France;
| | - Leonardo Lo Presti
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy; (G.B.); (L.L.P.)
| | - Carlo Gatti
- CNR–SCITEC, Istituto di Scienze e Tecnologie Chimiche sezione di via Golgi, c/o Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
- Istituto Lombardo, Accademia di Scienze e Lettere, via Brera 28, 20100 Milano, Italy
- Correspondence:
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10
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Scatena R, Montisci F, Lanza A, Casati NPM, Macchi P. Magnetic Network on Demand: Pressure Tunes Square Lattice Coordination Polymers Based on {[Cu(pyrazine) 2] 2+} n. Inorg Chem 2020; 59:10091-10098. [PMID: 32615765 PMCID: PMC8008383 DOI: 10.1021/acs.inorgchem.0c01229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the pressure-induced structural and magnetic changes in [CuCl(pyz)2](BF4) (pyz = pyrazine) and [CuBr(pyz)2](BF4), two members of a family of three-dimensional coordination polymers based on square mesh {[Cu(pyz)2]2+}n layers. High-pressure X-ray diffraction and density functional theory calculations have been used to investigate the structure-magnetic property relationship. Although structurally robust and almost undeformed within a large pressure range, the {[Cu(pyz)2]2+}n network can be electronically modified by adjusting the interaction of the apical linkers interconnecting the layers, which has strong implications for the magnetic properties. It is then demonstrated that the degree of covalent character of the apical interaction explains the difference in magnetic exchange between the two species. We have also investigated the mechanical deformation of the network induced by nonhydrostatic compression that affects the structure depending on the crystal orientation. The obtained results suggest the existence of "Jahn-Teller frustration" triggered at the highest hydrostatic pressure limit.
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Affiliation(s)
- Rebecca Scatena
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Fabio Montisci
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Arianna Lanza
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Nicola P M Casati
- Paul Scherrer Institute, Laboratory for Synchrotron Radiation Condensed Matter, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Piero Macchi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.,Department of Chemistry, Materials and Chemical Engineering, Polytechnic of Milan, via Mancinelli 7, 20131 Milan, Italy
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11
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Monroe JC, Landee CP, Turnbull MM, Wikaira JL. Well-isolated pyrazine-bridged copper(II) chains: synthesis and magneto-structural analysis. J COORD CHEM 2020. [DOI: 10.1080/00958972.2020.1789972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Jeffrey C. Monroe
- Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, USA
| | | | - Mark M. Turnbull
- Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, USA
| | - Jan L. Wikaira
- School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
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12
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13
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Dos Santos LH. Applications of charge-density analysis to the rational design of molecular materials: A mini review on how to engineer optical or magnetic crystals. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Tolborg K, Iversen BB. Electron Density Studies in Materials Research. Chemistry 2019; 25:15010-15029. [DOI: 10.1002/chem.201903087] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 08/13/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Kasper Tolborg
- Center for Materials CrystallographyDepartment of Chemistry and iNANOAarhus University Langelandsgade 140 8000 Aarhus C Denmark
| | - Bo B. Iversen
- Center for Materials CrystallographyDepartment of Chemistry and iNANOAarhus University Langelandsgade 140 8000 Aarhus C Denmark
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15
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Zhigulin GY, Zabrodina GS, Katkova MA, Ketkov SY. Polynuclear Glycinehydroximate Cu(II)–Gd(III) Metallamacrocyclic Complexes: Halochromic Properties. RUSS J COORD CHEM+ 2019. [DOI: 10.1134/s107032841905004x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Scatena R, Guntern YT, Macchi P. Electron Density and Dielectric Properties of Highly Porous MOFs: Binding and Mobility of Guest Molecules in Cu 3(BTC) 2 and Zn 3(BTC) 2. J Am Chem Soc 2019; 141:9382-9390. [PMID: 31129957 DOI: 10.1021/jacs.9b03643] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two isostructural highly porous metal-organic frameworks, the well-known {Cu3(BTC)2} n (BTC = 1,3,5-benzenetricarboxylate), often appointed with the name HKUST-1, and {Zn3(BTC)2} n, have been investigated as models for the buildup of dielectric properties, differentiating the role of chemi- and physisorbed guest molecules and that of specific intraframework and framework-guest linkages. For this purpose, electron charge density analysis, impedance spectroscopy, density functional theory simulations, and atomic partitioning of the polarizabilities have been exploited. These analyses at different degrees of pores filling enabled one to observe structural and electronic changes induced by guest molecules, especially when chemisorbed. The electrostatic potential inside the pores allows one to describe the absorption mechanism and to estimate the polarization of guests induced by the framework. The dielectric constant shows very diverse frequency dependence and magnitude of real and imaginary components as a consequence of (I) capture of guest molecules in the pores during synthesis, (II) MOF activation, and (III) water absorption from the atmosphere after activation. Comparison with calculated static-dielectric constant and atomic polarizabilities of the material has allowed for evaluating building blocks' contribution to the overall property, paving the way for reverse crystal engineering of these species.
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Affiliation(s)
- Rebecca Scatena
- Department for Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , Bern 3012 , Switzerland
| | - Yannick T Guntern
- Department for Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , Bern 3012 , Switzerland
| | - Piero Macchi
- Department for Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , Bern 3012 , Switzerland.,Department of Chemistry, Materials and Chemical Engineering , Polytechnic of Milan , via Mancinelli 7 , Milano 20131 , Italy
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17
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Huddart BM, Brambleby J, Lancaster T, Goddard PA, Xiao F, Blundell SJ, Pratt FL, Singleton J, Macchi P, Scatena R, Barton AM, Manson JL. Magnetic order and enhanced exchange in the quasi-one-dimensional molecule-based antiferromagnet Cu(NO 3) 2(pyz) 3. Phys Chem Chem Phys 2019; 21:1014-1018. [PMID: 30574636 DOI: 10.1039/c8cp07160h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quasi-one-dimensional molecule-based Heisenberg antiferromagnet Cu(NO3)2(pyz)3 has an intrachain coupling J = 13.7(1) K () and exhibits a state of long-range magnetic order below TN = 0.105(1) K. The ratio of interchain to intrachain coupling is estimated to be |J'/J| = 3.3 × 10-3, demonstrating a high degree of isolation for the Cu chains.
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Affiliation(s)
- Benjamin M Huddart
- Centre for Materials Physics, Durham University, South Road, Durham DH1 3LE, UK.
| | - Jamie Brambleby
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Tom Lancaster
- Centre for Materials Physics, Durham University, South Road, Durham DH1 3LE, UK.
| | - Paul A Goddard
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Fan Xiao
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland and Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Stephen J Blundell
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Francis L Pratt
- ISIS Pulsed Muon Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
| | - John Singleton
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS-E536, Los Alamos, New Mexico 87545, USA
| | - Piero Macchi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland and Polytechnic of Milan, Department of Chemistry, Materials and Chemical Engineering, via Mancinelli 7 20131, Milan, Italy
| | - Rebecca Scatena
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Alyssa M Barton
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, Washington 99004, USA.
| | - Jamie L Manson
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, Washington 99004, USA.
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18
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Wehinger B, Fiolka C, Lanza A, Scatena R, Kubus M, Grockowiak A, Coniglio WA, Graf D, Skoulatos M, Chen JH, Gukelberger J, Casati N, Zaharko O, Macchi P, Krämer KW, Tozer S, Mudry C, Normand B, Rüegg C. Giant Pressure Dependence and Dimensionality Switching in a Metal-Organic Quantum Antiferromagnet. PHYSICAL REVIEW LETTERS 2018; 121:117201. [PMID: 30265101 DOI: 10.1103/physrevlett.121.117201] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Indexed: 06/08/2023]
Abstract
We report an extraordinary pressure dependence of the magnetic interactions in the metal-organic system [CuF_{2}(H_{2}O)_{2}]_{2}pyrazine. At zero pressure, this material realizes a quasi-two-dimensional spin-1/2 square-lattice Heisenberg antiferromagnet. By high-pressure, high-field susceptibility measurements we show that the dominant exchange parameter is reduced continuously by a factor of 2 on compression. Above 18 kbar, a phase transition occurs, inducing an orbital re-ordering that switches the dimensionality, transforming the quasi-two-dimensional lattice into weakly coupled chains. We explain the microscopic mechanisms for both phenomena by combining detailed x-ray and neutron diffraction studies with quantitative modeling using spin-polarized density functional theory.
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Affiliation(s)
- B Wehinger
- Department of Quantum Matter Physics, University of Geneva, 24, Quai Ernest Ansermet, CH-1211 Genève, Switzerland
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - C Fiolka
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - A Lanza
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - R Scatena
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - M Kubus
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - A Grockowiak
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - W A Coniglio
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - D Graf
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - M Skoulatos
- Heinz-Maier-Leibnitz Zentrum and Physics Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - J-H Chen
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
- Theoretical Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - J Gukelberger
- Theoretical Physics, ETH Zürich, CH-8093 Zürich, Switzerland
- Département de Physique and Institut Quantique, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada
| | - N Casati
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - O Zaharko
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - P Macchi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - K W Krämer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - S Tozer
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - C Mudry
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - B Normand
- Neutrons and Muons Research Division, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - Ch Rüegg
- Department of Quantum Matter Physics, University of Geneva, 24, Quai Ernest Ansermet, CH-1211 Genève, Switzerland
- Neutrons and Muons Research Division, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
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19
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Herich P, Kucková L, Moncol J, Kožíšek J. Charge density study of bis(clonixato)bis(ethanol) bis(imidazole)copper(II) complex. Z KRIST-CRYST MATER 2018. [DOI: 10.1515/zkri-2018-2070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Abstract
An experimental electronic structure of bis(clonixato)bis(ethanol) bis(imidazole)copper(II) complex, [Cu(cln)2(im)2(EtOH)2] (cln=clonixato, im=imidazole) (1) has been obtained from single-crystal X-ray diffraction data collected at 100 K using an Incoatec IμS Ag microfocus source. Metal-ligand (ML) bonds and hydrogen bonds (HBs) have been analysed using topological analysis of the experimental electron density with the atoms in molecules (AIM) approach. The central copper atom is octahedrally coordinated by two oxygen atoms from two clonixato anions and two nitrogen atoms from two imidazole ligands in equatorial plane. In axial positions are two oxygen atoms from two ethanol molecules. AIM analysis establishes that the central copper atom is bonded more strongly to the clonixato anion that to the imidazole or ethanol molecules. AIM analysis of two intramolecular and one intermolecular hydrogen bonds permits to estimate their strength. We show that the hydrogen bonds are strong enough to protect the molecule from decomposition in solvent media and to disable the more reactive imidazole-Cu-clonixato complex from interacting with e.g. a macromolecule. The electrostatic potential of the complex shows a highly positive value on the central atom, so the complex is highly reactive in an interaction with negative ligands.
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Affiliation(s)
- Peter Herich
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , SK-812 37 Bratislava , Slovakia
| | - Lenka Kucková
- Department of Chemistry , Constantine the Philosopher University, Trieda A. Hlinku 1 , SK-949 74 Nitra , Slovakia
| | - Jan Moncol
- Institute of Inorganic Chemistry, Technology and Materials, Faculty of Chemical and Food Technology, Slovak University of Technology , SK-812 37 Bratislava , Slovakia
| | - Jozef Kožíšek
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , SK-812 37 Bratislava , Slovakia
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20
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Genoni A, Bučinský L, Claiser N, Contreras-García J, Dittrich B, Dominiak PM, Espinosa E, Gatti C, Giannozzi P, Gillet JM, Jayatilaka D, Macchi P, Madsen AØ, Massa L, Matta CF, Merz KM, Nakashima PNH, Ott H, Ryde U, Schwarz K, Sierka M, Grabowsky S. Quantum Crystallography: Current Developments and Future Perspectives. Chemistry 2018; 24:10881-10905. [PMID: 29488652 DOI: 10.1002/chem.201705952] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/27/2018] [Indexed: 11/09/2022]
Abstract
Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the accuracy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate discussions around QCr, but not to find a final definition of the field.
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Affiliation(s)
- Alessandro Genoni
- Université de Lorraine, CNRS, Laboratoire LPCT, 1 Boulevard Arago, F-57078, Metz, France
| | - Lukas Bučinský
- Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology, FCHPT SUT, Radlinského 9, SK-812 37, Bratislava, Slovakia
| | - Nicolas Claiser
- Université de Lorraine, CNRS, Laboratoire CRM2, Boulevard des Aiguillettes, BP 70239, F-54506, Vandoeuvre-lès-Nancy, France
| | - Julia Contreras-García
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire de Chimie Théorique (LCT), 4 Place Jussieu, F-75252, Paris Cedex 05, France
| | - Birger Dittrich
- Anorganische und Strukturchemie II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Paulina M Dominiak
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, 02-089, Warszawa, Poland
| | - Enrique Espinosa
- Université de Lorraine, CNRS, Laboratoire CRM2, Boulevard des Aiguillettes, BP 70239, F-54506, Vandoeuvre-lès-Nancy, France
| | - Carlo Gatti
- CNR-ISTM Istituto di Scienze e Tecnologie Molecolari, via Golgi 19, Milano, I-20133, Italy.,Istituto Lombardo Accademia di Scienze e Lettere, via Brera 28, 20121, Milano, Italy
| | - Paolo Giannozzi
- Department of Mathematics, Computer Science and Physics, University of Udine, Via delle Scienze 208, I-33100, Udine, Italy
| | - Jean-Michel Gillet
- Structure, Properties and Modeling of Solids Laboratory, CentraleSupelec, Paris-Saclay University, 3 rue Joliot-Curie, 91191, Gif-sur-Yvette, France
| | - Dylan Jayatilaka
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Piero Macchi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland
| | - Anders Ø Madsen
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Lou Massa
- Hunter College & the Ph.D. Program of the Graduate Center, City University of New York, New York, USA
| | - Chérif F Matta
- Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, B3M 2J6, Canada.,Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada.,Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada.,Département de Chimie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Kenneth M Merz
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan, 48824, USA.,Institute for Cyber Enabled Research, Michigan State University, 567 Wilson Road, Room 1440, East Lansing, Michigan, 48824, USA
| | - Philip N H Nakashima
- Department of Materials Science and Engineering, Monash University, Victoria, 3800, Australia
| | - Holger Ott
- Bruker AXS GmbH, Östliche Rheinbrückenstraße 49, 76187, Karlsruhe, Germany
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, SE-22100, Lund, Sweden
| | - Karlheinz Schwarz
- Technische Universität Wien, Institut für Materialwissenschaften, Getreidemarkt 9, A-1060, Vienna, Austria
| | - Marek Sierka
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743, Jena, Germany
| | - Simon Grabowsky
- Fachbereich 2-Biologie/Chemie, Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Str. 3, 28359, Bremen, Germany
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21
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Kubus M, Lanza A, Scatena R, Dos Santos LHR, Wehinger B, Casati N, Fiolka C, Keller L, Macchi P, Rüegg C, Krämer KW. Quasi-2D Heisenberg Antiferromagnets [CuX(pyz) 2](BF 4) with X = Cl and Br. Inorg Chem 2018; 57:4934-4943. [PMID: 29389126 DOI: 10.1021/acs.inorgchem.7b03150] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two Cu2+ coordination polymers [CuCl(pyz)2](BF4) 1 and [CuBr(pyz)2](BF4) 2 (pyz = pyrazine) were synthesized in the family of quasi two-dimensional (2D) [Cu(pyz)2]2+ magnetic networks. The layer connectivity by monatomic halide ligands results in significantly shorter interlayer distances. Structures were determined by single-crystal X-ray diffraction. Temperature-dependent X-ray diffraction of 1 revealed rigid [Cu(pyz)2]2+ layers that do not expand between 5 K and room temperature, whereas the expansion along the c-axis amounts to 2%. The magnetic susceptibility of 1 and 2 shows a broad maximum at ∼8 K, indicating antiferromagnetic interactions within the [Cu(pyz)2]2+ layers. 2D Heisenberg model fits result in J∥ = 9.4(1) K for 1 and 8.9(1) K for 2. The interlayer coupling is much weaker with | J⊥| = 0.31(6) K for 1 and 0.52(9) K for 2. The electron density, experimentally determined and calculated by density functional theory, confirms the location of the singly occupied orbital (the magnetic orbital) in the tetragonal plane. The analysis of the spin density reveals a mainly σ-type exchange through pyrazine. Kinks in the magnetic susceptibility indicate the onset of long-range three-dimensional magnetic order below 4 K. The magnetic structures were determined by neutron diffraction. Magnetic Bragg peaks occur below TN = 3.9(1) K for 1 and 3.8(1) K for 2. The magnetic unit cell is doubled along the c-axis ( k = 0, 0, 0.5). The ordered magnetic moments are located in the tetragonal plane and amount to 0.76(8) μB/Cu2+ for 1 and 0.6(1) μB/Cu2+ for 2 at 1.5 K. The moments are coupled antiferromagnetically both in the ab plane and along the c-axis. The Cu2+ g-tensor was determined from electron spin resonance spectra as g x = 2.060(1), g z = 2.275(1) for 1 and g x = 2.057(1), g z = 2.272(1) for 2 at room temperature.
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Affiliation(s)
- Mariusz Kubus
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | - Arianna Lanza
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | - Rebecca Scatena
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | - Leonardo H R Dos Santos
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | - Björn Wehinger
- Department of Quantum Matter Physics , University of Geneva , Quai Ernest Ansermet 24 , CH-1211 Genève 4 , Switzerland
| | | | - Christoph Fiolka
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | | | - Piero Macchi
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
| | - Christian Rüegg
- Department of Quantum Matter Physics , University of Geneva , Quai Ernest Ansermet 24 , CH-1211 Genève 4 , Switzerland
| | - Karl W Krämer
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , CH-3012 Bern , Switzerland
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22
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Gatti C, Macetti G, Lo Presti L. Insights on spin delocalization and spin polarization mechanisms in crystals of azido copper(II) dinuclear complexes through the electron spin density Source Function. ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS 2017; 73:565-583. [DOI: 10.1107/s2052520617008083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/31/2017] [Indexed: 11/11/2022]
Abstract
The Source Function (SF) tool was applied to the analysis of thetheoreticalspin density in azido CuIIdinuclear complexes, where the azido group, acting as a coupler between the CuIIcations, is linked to the metal centres either in an end-on or in an end–end fashion. Results for only the former structural arrangement are reported in the present paper. The SF highlights to which extent the magnetic centres contribute to determine the local spin delocalization and polarization at any point in the dimetallic complex and whether an atom or group of atoms of the ligands act in favour or against a given local spin delocalization/polarization. Ball-and-stick atomic SF percentage representations allow for a visualization of the magnetic pathways and of the specific role played by each atom along these paths, at given reference points. Decomposition of SF contributions in terms of a magnetic and of a relaxation component provides further insight. Reconstruction of partial spin densities by means of the Source Function has for the first time been introduced. At variance with the standard SF percentage representations, such reconstructions offer a simultaneous view of the sources originating from specific subsets of contributing atoms, in a selected molecular plane or in the whole space, and are therefore particularly informative. The SF tool is also used to evaluate the accuracy of the analysed spin densities. It is found that those obtained at the unrestricted B3LYP DFT level, relative to those computed at the CASSCF(6,6) level, greatly overestimate spin delocalization to the ligands, but comparatively underestimate magnetic connection (spin transmission) among atoms, along the magnetic pathways. As a consequence of its excessive spin delocalization, the UB3LYP method also overestimates spin polarization mechanisms between the paramagnetic centres and the ligands. Spin delocalization measures derived from the refinement of Polarized Neutron Diffraction data seem in general superior to those obtained through the DFT UB3LYP approach and closer to the far more accurate CASSCF results. It is also shown that a visual agreement on the spin-resolved electron densities ραand ρβderived from different approaches does not warrant a corresponding agreement between their associated spin densities.
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23
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Krause L, Niepötter B, Schürmann CJ, Stalke D, Herbst-Irmer R. Validation of experimental charge-density refinement strategies: when do we overfit? IUCRJ 2017; 4:420-430. [PMID: 28875029 PMCID: PMC5571805 DOI: 10.1107/s2052252517005103] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 04/03/2017] [Indexed: 06/07/2023]
Abstract
A cross-validation method is supplied to judge between various strategies in multipole refinement procedures. Its application enables straightforward detection of whether the refinement of additional parameters leads to an improvement in the model or an overfitting of the given data. For all tested data sets it was possible to prove that the multipole parameters of atoms in comparable chemical environments should be constrained to be identical. In an automated approach, this method additionally delivers parameter distributions of k different refinements. These distributions can be used for further error diagnostics, e.g. to detect erroneously defined parameters or incorrectly determined reflections. Visualization tools show the variation in the parameters. These different refinements also provide rough estimates for the standard deviation of topological parameters.
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Affiliation(s)
- Lennard Krause
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany
| | - Benedikt Niepötter
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany
| | - Christian J. Schürmann
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany
| | - Dietmar Stalke
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany
| | - Regine Herbst-Irmer
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany
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24
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25
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Hofmann D, Gans E, Krüll J, Heinrich MR. Sustainable Synthesis of Balsalazide and Sulfasalazine Based on Diazotization with Low Concentrations of Nitrogen Dioxide in Air. Chemistry 2017; 23:4042-4045. [PMID: 28054726 DOI: 10.1002/chem.201605359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Indexed: 01/07/2023]
Abstract
Low concentrations of nitrogen dioxide, which arises as a side product from a range of industrial processes, can effectively be recycled through the diazotization of anilines. The studies reported herein now demonstrate that the removal of nitrogen dioxide from gas streams is even more effective when hydrophilic anilines are used as starting materials. The diazonium salts, which are obtained in this way in up to quantitative yields, can directly be employed in azo coupling reactions, thus opening up an attractive route to the industrially important group of azo compounds.
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Affiliation(s)
- Dagmar Hofmann
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schuhstraße 19, 91052, Erlangen, Germany
| | - Eva Gans
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schuhstraße 19, 91052, Erlangen, Germany
| | - Jasmin Krüll
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schuhstraße 19, 91052, Erlangen, Germany
| | - Markus R Heinrich
- Department of Chemistry and Pharmacy, Pharmaceutical Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schuhstraße 19, 91052, Erlangen, Germany
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26
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Manson JL, Schlueter JA, Garrett KE, Goddard PA, Lancaster T, Möller JS, Blundell SJ, Steele AJ, Franke I, Pratt FL, Singleton J, Bendix J, Lapidus SH, Uhlarz M, Ayala-Valenzuela O, McDonald RD, Gurak M, Baines C. Bimetallic MOFs (H3O)x[Cu(MF6)(pyrazine)2]·(4 − x)H2O (M = V4+, x = 0; M = Ga3+, x = 1): co-existence of ordered and disordered quantum spins in the V4+ system. Chem Commun (Camb) 2016; 52:12653-12656. [DOI: 10.1039/c6cc05873f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
These bimetallic MOFs contain [Cu(pyz)2]2+ sheets and MF6n− octahedra whereby only the Cu(ii) moments magnetically order.
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