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Pask CM, Greatorex S, Kulmaczewski R, Baldansuren A, McInnes EJL, Bamiduro F, Yamada M, Yoshinari N, Konno T, Halcrow MA. Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin-Crossover Compound From its Copper(II) and Zinc(II) Congeners. Chemistry 2020; 26:4833-4841. [PMID: 32017244 DOI: 10.1002/chem.202000101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Indexed: 11/12/2022]
Abstract
Annealing [FeL2 ][BF4 ]2 ⋅2 H2 O (L=2,6-bis-[5-methyl-1H-pyrazol-3-yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2 =205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2 ][BF4 ]2 ⋅2 H2 O and [ZnL2 ][BF4 ]2 ⋅2 H2 O are not perfectly isostructural but, unlike the iron compound, they undergo single-crystal-to-single-crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re-cooling. The low-temperature phase of [CuL2 ][BF4 ]2 involves ordering of its Jahn-Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low-temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high-spin iron compound, before the onset of spin-crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper-doped [Fe0.97 Cu0.03 L2 ][BF4 ]2 imply its low-spin phase contains two distinct cation environments in a 2:1 ratio.
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Affiliation(s)
- Christopher M Pask
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Sam Greatorex
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Amgalanbaatar Baldansuren
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,current address: Chemistry and Chemical Biology, 120 Cogswell, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY, 12180, USA
| | - Eric J L McInnes
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Faith Bamiduro
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.,current address: Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.,Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
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Polyzou CD, Malina O, Tuček J, Zbořil R, Panagiotou N, Tasiopoulos AJ, Boukos N, Parthenios J, Kalarakis AN, Tangoulis V. Spin-Crossover Phenomenon in Microcrystals and Nanoparticles of a [Fe(2-mpz) 2Ni(CN) 4] Two-Dimensional Hofmann-Type Polymer: A Detailed Nano-Topographic Study. Inorg Chem 2019; 58:13733-13736. [PMID: 31573185 DOI: 10.1021/acs.inorgchem.9b01405] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The diamagnetic two-dimensional Hofmann-type metal-organic framework [ZnII(2-mpz)2Ni(CN)4] has been successfully synthesized along with its isostructural hysteretic spin-crossover FeII analogue in the form of both bulk microcrystalline powder and nanoparticles. Detailed atomic force microscopy topographic study revealed a nanogrowth relationship between the height and length of the nanoparticle.
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Affiliation(s)
- Christina D Polyzou
- Laboratory of Inorganic Chemistry, Department of Chemistry , University of Patras , 26504 Patras , Greece
| | - Ondřej Malina
- Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, Faculty of Science , Palacký University Olomouc , Šlechtitelů 27 , 783 71 Olomouc , Czech Republic
| | - Jiri Tuček
- Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, Faculty of Science , Palacký University Olomouc , Šlechtitelů 27 , 783 71 Olomouc , Czech Republic
| | - Radek Zbořil
- Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, Faculty of Science , Palacký University Olomouc , Šlechtitelů 27 , 783 71 Olomouc , Czech Republic
| | - Nikos Panagiotou
- Department of Chemistry , University of Cyprus , 1678 Nicosia , Cyprus
| | | | - Nikos Boukos
- Institute of Nanoscience and Nanotechnology , NCSR "Demokritos" , 153 10 Aghia Paraskevi Attikis , Greece
| | - John Parthenios
- Foundation for Research and Technology-Hellas, Institute of Chemical Engineering Sciences , Stadiou Str. Platani , 265 04 Patras , Greece
| | - Alexandros N Kalarakis
- Department of Mechanical Engineering , University of Peloponnese , GR-26334 Patras , Greece
| | - Vassilis Tangoulis
- Laboratory of Inorganic Chemistry, Department of Chemistry , University of Patras , 26504 Patras , Greece
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Palii A, Ostrovsky S, Reu O, Tsukerblat B, Decurtins S, Liu SX, Klokishner S. Microscopic theory of cooperative spin crossover: Interaction of molecular modes with phonons. J Chem Phys 2015; 143:084502. [PMID: 26328851 DOI: 10.1063/1.4928642] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this article, we present a new microscopic theoretical approach to the description of spin crossover in molecular crystals. The spin crossover crystals under consideration are composed of molecular fragments formed by the spin-crossover metal ion and its nearest ligand surrounding and exhibiting well defined localized (molecular) vibrations. As distinguished from the previous models of this phenomenon, the developed approach takes into account the interaction of spin-crossover ions not only with the phonons but also a strong coupling of the electronic shells with molecular modes. This leads to an effective coupling of the local modes with phonons which is shown to be responsible for the cooperative spin transition accompanied by the structural reorganization. The transition is characterized by the two order parameters representing the mean values of the products of electronic diagonal matrices and the coordinates of the local modes for the high- and low-spin states of the spin crossover complex. Finally, we demonstrate that the approach provides a reasonable explanation of the observed spin transition in the [Fe(ptz)6](BF4)2 crystal. The theory well reproduces the observed abrupt low-spin → high-spin transition and the temperature dependence of the high-spin fraction in a wide temperature range as well as the pronounced hysteresis loop. At the same time within the limiting approximations adopted in the developed model, the evaluated high-spin fraction vs. T shows that the cooperative spin-lattice transition proves to be incomplete in the sense that the high-spin fraction does not reach its maximum value at high temperature.
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Affiliation(s)
- Andrew Palii
- Institute of Applied Physics, Academy of Sciences of Moldova, Academy Str. 5, MD-2028 Kishinev, Moldova
| | - Serghei Ostrovsky
- Institute of Applied Physics, Academy of Sciences of Moldova, Academy Str. 5, MD-2028 Kishinev, Moldova
| | - Oleg Reu
- Institute of Applied Physics, Academy of Sciences of Moldova, Academy Str. 5, MD-2028 Kishinev, Moldova
| | - Boris Tsukerblat
- Department of Chemistry, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel
| | - Silvio Decurtins
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Shi-Xia Liu
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Sophia Klokishner
- Institute of Applied Physics, Academy of Sciences of Moldova, Academy Str. 5, MD-2028 Kishinev, Moldova
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Pápai M, Vankó G, de Graaf C, Rozgonyi T. Theoretical Investigation of the Electronic Structure of Fe(II) Complexes at Spin-State Transitions. J Chem Theory Comput 2012; 9:509-519. [PMID: 25821416 PMCID: PMC4358629 DOI: 10.1021/ct300932n] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Indexed: 01/30/2023]
Abstract
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The electronic structure relevant to low spin (LS)↔high
spin (HS) transitions in Fe(II) coordination compounds with a FeN6 core are studied. The selected [Fe(tz)6]2+ (1) (tz = 1H-tetrazole), [Fe(bipy)3]2+ (2) (bipy = 2,2′-bipyridine), and [Fe(terpy)2]2+ (3) (terpy = 2,2′:6′,2″-terpyridine)
complexes have been actively studied experimentally, and with their
respective mono-, bi-, and tridentate ligands, they constitute a comprehensive
set for theoretical case studies. The methods in this work include
density functional theory (DFT), time-dependent DFT (TD-DFT), and
multiconfigurational second order perturbation theory (CASPT2). We
determine the structural parameters as well as the energy splitting
of the LS–HS states (ΔEHL) applying the above methods and comparing their performance. We
also determine the potential energy curves representing the ground
and low-energy excited singlet, triplet, and quintet d6 states along the mode(s) that connect the LS and HS states. The
results indicate that while DFT is well suited for the prediction
of structural parameters, an accurate multiconfigurational approach
is essential for the quantitative determination of ΔEHL. In addition, a good qualitative agreement
is found between the TD-DFT and CASPT2 potential energy curves. Although
the TD-DFT results might differ in some respect (in our case, we found
a discrepancy at the triplet states), our results suggest that this
approach, with due care, is very promising as an alternative for the
very expensive CASPT2 method. Finally, the two-dimensional (2D) potential
energy surfaces above the plane spanned by the two relevant configuration
coordinates in [Fe(terpy)2]2+ were computed
at both the DFT and CASPT2 levels. These 2D surfaces indicate that
the singlet–triplet and triplet–quintet states are separated
along different coordinates, i.e., different vibration modes. Our
results confirm that in contrast to the case of complexes with mono-
and bidentate ligands, the singlet–quintet transitions in [Fe(terpy)2]2+ cannot be described using a single configuration
coordinate.
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Affiliation(s)
- Mátyás Pápai
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
| | - György Vankó
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary
| | - Coen de Graaf
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain ; Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010, Barcelona, Spain
| | - Tamás Rozgonyi
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1025 Budapest, Pusztaszeri út 59-67, Hungary
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