Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition
A new 1D-coordination polymer [Co(Piv)<sub>2</sub>(NH<sub>2</sub>(CH<sub>2</sub>)<sub>6</sub>NH<sub>2</sub>)]<sub>n</sub> (<b>1</b>, Piv is Me<sub>3</sub>CCO<sub>2</sub><sup>−</sup>...
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MDPI AG
2022-12-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/1/215 |
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| author | Dmitriy S. Yambulatov Julia K. Voronina Alexander S. Goloveshkin Roman D. Svetogorov Sergey L. Veber Nikolay N. Efimov Anna K. Matyukhina Stanislav A. Nikolaevskii Igor L. Eremenko Mikhail A. Kiskin |
| author_facet | Dmitriy S. Yambulatov Julia K. Voronina Alexander S. Goloveshkin Roman D. Svetogorov Sergey L. Veber Nikolay N. Efimov Anna K. Matyukhina Stanislav A. Nikolaevskii Igor L. Eremenko Mikhail A. Kiskin |
| author_sort | Dmitriy S. Yambulatov |
| collection | DOAJ |
| description | A new 1D-coordination polymer [Co(Piv)<sub>2</sub>(NH<sub>2</sub>(CH<sub>2</sub>)<sub>6</sub>NH<sub>2</sub>)]<sub>n</sub> (<b>1</b>, Piv is Me<sub>3</sub>CCO<sub>2</sub><sup>−</sup> anion) was obtained, the mononuclear fragments {Co(O<sub>2</sub>CR)<sub>2</sub>} within which are linked by μ-bridged molecules of hexamethylenediamine (NH<sub>2</sub>(CH<sub>2</sub>)<sub>6</sub>NH<sub>2</sub>). For this compound, two different monoclinic <i>C</i>2/<i>c</i> (α-<b>1</b>) and <i>P</i>2/<i>n</i> (β-<b>1</b>) phases were found at room temperature by single-crystal X-ray diffraction analysis, with a similar structure of chains and their packages in unit cells. The low-temperature phase (γ-<b>1</b>) of crystal <b>1</b> at 150 K corresponds to the triclinic space group <i>P</i>-1. As the temperature decreases, the structural phase transition (SPT) in the α-<b>1</b> and β-<b>1</b> crystals is accompanied by an increase in the crystal packing density caused by the rearrangements of both H-bonds and the nearest ligand environment of the cobalt atom (“octahedral CoN<sub>2</sub>O<sub>4</sub> around the metal center at room temperature” → “pseudo-tetrahedral CoN<sub>2</sub>O<sub>2</sub> at 150 K”). The SPT was confirmed by DSC in the temperature range 210–150 K; when heated above 220 K, anomalies in the behavior of the heat flow are observed, which may be associated with the reversibility of SPT; endo effects are observed up to 300 K. The SPT starts below 200 K. At 100 K, a mixture of phases was found in sample <b>1</b>: 27% α-<b>1</b> phase, 61% γ-<b>1</b> phase. In addition, at 100 K, 12% of the new δ-<b>1</b> phase was detected, which was identified from the diffraction pattern at 260 K upon subsequent heating: the <i>a</i>,<i>b</i>,<i>c</i>-parameters and unit cell volume are close to the structure parameters of γ-<b>1</b>, and the values of the α,β,γ-angles are significantly different. Further heating leads to a phase transition from δ-<b>1</b> to α-<b>1</b>, which both coexist at room temperature. According to the DC magnetometry data, during cooling and heating, the χ<sub>M</sub><i>T</i>(<i>T</i>) curves for <b>1</b> form a hysteresis loop with ~110 K, in which the difference in the χ<sub>M</sub><i>T</i> values reaches 9%. Ab initio calculations of the electronic structure of cobalt(II) in α-<b>1</b> and γ-<b>1</b> have been performed. Based on the EPR data at 10 K and the ab initio calculations, the behavior of the χ<sub>M</sub><i>T</i>(<i>T</i>) curve for <b>1</b> was simulated in the temperature range of 2–150 K. It was found that <b>1</b> exhibits slow magnetic relaxation in a field of 1000 Oe. |
| first_indexed | 2024-03-09T09:44:48Z |
| format | Article |
| id | doaj.art-7f3bc8627300455f98b7efc268b6c1dc |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T09:44:48Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-7f3bc8627300455f98b7efc268b6c1dc2023-12-02T00:38:20ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-12-0124121510.3390/ijms24010215Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase TransitionDmitriy S. Yambulatov0Julia K. Voronina1Alexander S. Goloveshkin2Roman D. Svetogorov3Sergey L. Veber4Nikolay N. Efimov5Anna K. Matyukhina6Stanislav A. Nikolaevskii7Igor L. Eremenko8Mikhail A. Kiskin9N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow, RussiaNational Research Center “Kurchatov Institute”, 123182 Moscow, RussiaInstitute “International Tomography Center”, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, RussiaA new 1D-coordination polymer [Co(Piv)<sub>2</sub>(NH<sub>2</sub>(CH<sub>2</sub>)<sub>6</sub>NH<sub>2</sub>)]<sub>n</sub> (<b>1</b>, Piv is Me<sub>3</sub>CCO<sub>2</sub><sup>−</sup> anion) was obtained, the mononuclear fragments {Co(O<sub>2</sub>CR)<sub>2</sub>} within which are linked by μ-bridged molecules of hexamethylenediamine (NH<sub>2</sub>(CH<sub>2</sub>)<sub>6</sub>NH<sub>2</sub>). For this compound, two different monoclinic <i>C</i>2/<i>c</i> (α-<b>1</b>) and <i>P</i>2/<i>n</i> (β-<b>1</b>) phases were found at room temperature by single-crystal X-ray diffraction analysis, with a similar structure of chains and their packages in unit cells. The low-temperature phase (γ-<b>1</b>) of crystal <b>1</b> at 150 K corresponds to the triclinic space group <i>P</i>-1. As the temperature decreases, the structural phase transition (SPT) in the α-<b>1</b> and β-<b>1</b> crystals is accompanied by an increase in the crystal packing density caused by the rearrangements of both H-bonds and the nearest ligand environment of the cobalt atom (“octahedral CoN<sub>2</sub>O<sub>4</sub> around the metal center at room temperature” → “pseudo-tetrahedral CoN<sub>2</sub>O<sub>2</sub> at 150 K”). The SPT was confirmed by DSC in the temperature range 210–150 K; when heated above 220 K, anomalies in the behavior of the heat flow are observed, which may be associated with the reversibility of SPT; endo effects are observed up to 300 K. The SPT starts below 200 K. At 100 K, a mixture of phases was found in sample <b>1</b>: 27% α-<b>1</b> phase, 61% γ-<b>1</b> phase. In addition, at 100 K, 12% of the new δ-<b>1</b> phase was detected, which was identified from the diffraction pattern at 260 K upon subsequent heating: the <i>a</i>,<i>b</i>,<i>c</i>-parameters and unit cell volume are close to the structure parameters of γ-<b>1</b>, and the values of the α,β,γ-angles are significantly different. Further heating leads to a phase transition from δ-<b>1</b> to α-<b>1</b>, which both coexist at room temperature. According to the DC magnetometry data, during cooling and heating, the χ<sub>M</sub><i>T</i>(<i>T</i>) curves for <b>1</b> form a hysteresis loop with ~110 K, in which the difference in the χ<sub>M</sub><i>T</i> values reaches 9%. Ab initio calculations of the electronic structure of cobalt(II) in α-<b>1</b> and γ-<b>1</b> have been performed. Based on the EPR data at 10 K and the ab initio calculations, the behavior of the χ<sub>M</sub><i>T</i>(<i>T</i>) curve for <b>1</b> was simulated in the temperature range of 2–150 K. It was found that <b>1</b> exhibits slow magnetic relaxation in a field of 1000 Oe.https://www.mdpi.com/1422-0067/24/1/215cobalt(II) complexstructural phase transitionorbital angular momentumslow magnetic relaxationdynamic crystals |
| spellingShingle | Dmitriy S. Yambulatov Julia K. Voronina Alexander S. Goloveshkin Roman D. Svetogorov Sergey L. Veber Nikolay N. Efimov Anna K. Matyukhina Stanislav A. Nikolaevskii Igor L. Eremenko Mikhail A. Kiskin Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition International Journal of Molecular Sciences cobalt(II) complex structural phase transition orbital angular momentum slow magnetic relaxation dynamic crystals |
| title | Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition |
| title_full | Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition |
| title_fullStr | Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition |
| title_full_unstemmed | Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition |
| title_short | Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition |
| title_sort | change in the electronic structure of the cobalt ii ion in a one dimensional polymer with flexible linkers induced by a structural phase transition |
| topic | cobalt(II) complex structural phase transition orbital angular momentum slow magnetic relaxation dynamic crystals |
| url | https://www.mdpi.com/1422-0067/24/1/215 |
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