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Extending the family of reduced [Mn12O12(O2CR)16(H2O)x]n− complexes, and their sensitivity to environmental factors

Soler, Monica ; Mahalay, Preet ; Wernsdorfer, Wolfgang ; Lubert-Perquel, Daphné ; Huffman, John C. ; Abboud, Khalil A. ; Hill, Stephen ; Christou, George

Polyhedron, 2021-02, Vol.195 (C), p.114968, Article 114968 [Periódico revisado por pares]

United Kingdom: Elsevier Ltd

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  • Título:
    Extending the family of reduced [Mn12O12(O2CR)16(H2O)x]n− complexes, and their sensitivity to environmental factors
  • Autor: Soler, Monica ; Mahalay, Preet ; Wernsdorfer, Wolfgang ; Lubert-Perquel, Daphné ; Huffman, John C. ; Abboud, Khalil A. ; Hill, Stephen ; Christou, George
  • Assuntos: Clusters ; Crystal structures ; Magnetism ; Manganese
  • É parte de: Polyhedron, 2021-02, Vol.195 (C), p.114968, Article 114968
  • Notas: USDOE
  • Descrição: The [Mn12O12(O2CR)16(H2O)4]−.2− family of single-molecule magnets has been expanded with new members and the crystal structures of (PPh4)[Mn12O12(O2CCHCl2)16(H2O)4] and (PPh4)2[Mn12O12(O2CCH2Cl)16(H2O)3]. Crystals as grown exhibit three and two forms, respectively, with different relaxation rates, which collapse to a single form on vacuum-drying. This emphasizes a high sensitivity of the magnetic properties of such ultra-small nanomagnets to environmental influences. [Display omitted] •New reduced versions of Mn12 single-molecule magnets have been synthesized.•Crystal structures of one [Mn12]− and one [Mn12]2− salt have been obtained.•Remarkable sensitivity of the magnetic properties has been revealed by single-crystal hysteresis loop studies.•High sensitivity of ultra-small magnets to their solvation environment is an important factor in their potential application. The family of reduced [Mn12O12(O2CR)16(H2O)4]n− (n = 1, 2) single-molecule magnets (SMMs) has been expanded with the synthesis of new members using I− as a stoichiometric one-electron reducing agent of the neutral n = 0 complexes. Electrochemical data, 1H NMR spectra of the [Mn12O12(O2CCH2Cl)16(H2O)3]0,−,2− salts, and the crystal structures of two complexes, (PPh4)[Mn12O12(O2CCHCl2)16(H2O)4] and (PPh4)2[Mn12O12(O2CCH2Cl)16(H2O)3] have been obtained. For (PPh4)2[Mn12O12(O2CCH2Cl)16(H2O)3], the data confirm an S = 10 ground state, and magnetization vs dc field scans on a pristine crystal exhibit hysteresis loops possessing steps due to quantum tunneling of magnetization (QTM). In addition, two forms of the cluster have been identified in the crystal with distinctly different relaxation barriers, with the faster-relaxing form being the majority one in pristine crystals from mother liquor, and the slower-relaxing one becoming the majority one in vacuum-dried samples. Similar behavior is seen for (PPh4)[Mn12O12(O2CCHCl2)16(H2O)4] with an S = 19/2 ground state, which shows three forms to be present in the hysteresis loops of a pristine crystal, all converting to a slow-relaxing form on vacuum-drying. High-frequency EPR spectra of the latter confirm a high axial anisotropy with D = −0.477 cm−1 and rationalize its effective relaxation barrier Ueff = 57 K. The combined work emphasizes a high sensitivity of such ultra-small nanomagnets to environmental influences, affecting their properties significantly, especially their quantum properties that are so important to many potential new 21st century applications.
  • Editor: United Kingdom: Elsevier Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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