Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal

In this study, we comparatively analyzed the variable-temperature crystal structures for two isomorphous salts, [1-benzyl-4-aminopyridinium][M(mnt)<sub>2</sub>] (M = Ni or Cu; mnt<sup>2−</sup> = maleonitriledithiolate; labeled as <b>APy-Ni</b> or <b>APy-Cu&l...

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Main Authors: Yin Qian, Yan Gao, Lei Xu, Reinhard K. Kremer, Jin Zhang, Xiao-Ming Ren
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Magnetochemistry
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Online Access:https://www.mdpi.com/2312-7481/11/2/8
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author Yin Qian
Yan Gao
Lei Xu
Reinhard K. Kremer
Jin Zhang
Xiao-Ming Ren
author_facet Yin Qian
Yan Gao
Lei Xu
Reinhard K. Kremer
Jin Zhang
Xiao-Ming Ren
author_sort Yin Qian
collection DOAJ
description In this study, we comparatively analyzed the variable-temperature crystal structures for two isomorphous salts, [1-benzyl-4-aminopyridinium][M(mnt)<sub>2</sub>] (M = Ni or Cu; mnt<sup>2−</sup> = maleonitriledithiolate; labeled as <b>APy-Ni</b> or <b>APy-Cu</b>). Both salts crystallize in the triclinic <i>P</i>–1 space group at 296 K, comprising linear [M(mnt)<sub>2</sub>]<sup>−</sup> (M = Ni or Cu) tetramers. A magnetostructural phase transition occurs at T<sub>C</sub>~190 K in S = ½ <b>APy-Ni</b> at ambient pressure, with a conversion of paramagnetic tetramers into nonmagnetic spin-paired dimers. The discontinuous alteration of cell parameters at T<sub>C</sub> signifies the characteristic of first-order phase transition in <b>APy-Ni</b>. No such transition appears in the nonmagnetic <b>APy-Cu</b> within the same temperature vicinity, demonstrating the magnetic interactions promoting the structural phase transition in <b>APy-Ni</b>, which is further reinforced through a comparison of the lattice formation energy between <b>APy-Ni</b> and <b>APy-Cu</b>. The phase transition may bear a resemblance to the mechanisms typically observed in spin-Peierls systems. We further explored the magnetic and phase transition properties of <b>APy-Ni</b> under varying pressures. Significantly, T<sub>C</sub> shows a linear increase with rising pressure within the range of 0.003–0.88 GPa, with a rate of 90 K GPa<sup>−1</sup>, manifesting that the applied pressure promotes the transition from tetramer to dimer.
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spelling doaj-art-3d297070a86945ec86d86ccd108440c82025-08-20T02:44:42ZengMDPI AGMagnetochemistry2312-74812025-01-01112810.3390/magnetochemistry11020008Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular CrystalYin Qian0Yan Gao1Lei Xu2Reinhard K. Kremer3Jin Zhang4Xiao-Ming Ren5State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, ChinaState Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, ChinaState Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, ChinaMax-Planck-Institute für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, GermanyState Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, ChinaState Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, ChinaIn this study, we comparatively analyzed the variable-temperature crystal structures for two isomorphous salts, [1-benzyl-4-aminopyridinium][M(mnt)<sub>2</sub>] (M = Ni or Cu; mnt<sup>2−</sup> = maleonitriledithiolate; labeled as <b>APy-Ni</b> or <b>APy-Cu</b>). Both salts crystallize in the triclinic <i>P</i>–1 space group at 296 K, comprising linear [M(mnt)<sub>2</sub>]<sup>−</sup> (M = Ni or Cu) tetramers. A magnetostructural phase transition occurs at T<sub>C</sub>~190 K in S = ½ <b>APy-Ni</b> at ambient pressure, with a conversion of paramagnetic tetramers into nonmagnetic spin-paired dimers. The discontinuous alteration of cell parameters at T<sub>C</sub> signifies the characteristic of first-order phase transition in <b>APy-Ni</b>. No such transition appears in the nonmagnetic <b>APy-Cu</b> within the same temperature vicinity, demonstrating the magnetic interactions promoting the structural phase transition in <b>APy-Ni</b>, which is further reinforced through a comparison of the lattice formation energy between <b>APy-Ni</b> and <b>APy-Cu</b>. The phase transition may bear a resemblance to the mechanisms typically observed in spin-Peierls systems. We further explored the magnetic and phase transition properties of <b>APy-Ni</b> under varying pressures. Significantly, T<sub>C</sub> shows a linear increase with rising pressure within the range of 0.003–0.88 GPa, with a rate of 90 K GPa<sup>−1</sup>, manifesting that the applied pressure promotes the transition from tetramer to dimer.https://www.mdpi.com/2312-7481/11/2/8metal-bis-dithiolene saltthermotropic phase transitionpiezotropic phase transitionlinear tetramerspin-paired dimer
spellingShingle Yin Qian
Yan Gao
Lei Xu
Reinhard K. Kremer
Jin Zhang
Xiao-Ming Ren
Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
Magnetochemistry
metal-bis-dithiolene salt
thermotropic phase transition
piezotropic phase transition
linear tetramer
spin-paired dimer
title Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
title_full Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
title_fullStr Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
title_full_unstemmed Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
title_short Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
title_sort comprehensively understanding the transformation of paramagnetic tetramer to spin paired dimer in an s 1 2 molecular crystal
topic metal-bis-dithiolene salt
thermotropic phase transition
piezotropic phase transition
linear tetramer
spin-paired dimer
url https://www.mdpi.com/2312-7481/11/2/8
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AT yangao comprehensivelyunderstandingthetransformationofparamagnetictetramertospinpaireddimerinans1⁄2molecularcrystal
AT leixu comprehensivelyunderstandingthetransformationofparamagnetictetramertospinpaireddimerinans1⁄2molecularcrystal
AT reinhardkkremer comprehensivelyunderstandingthetransformationofparamagnetictetramertospinpaireddimerinans1⁄2molecularcrystal
AT jinzhang comprehensivelyunderstandingthetransformationofparamagnetictetramertospinpaireddimerinans1⁄2molecularcrystal
AT xiaomingren comprehensivelyunderstandingthetransformationofparamagnetictetramertospinpaireddimerinans1⁄2molecularcrystal