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Cutler DJ, Canaj AB, Singh MK, Nichol GS, Gracia D, Nojiri H, Evangelisti M, Schnack J, Brechin EK. Odd and Even Numbered Ferric Wheels. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304553. [PMID: 37635185 PMCID: PMC10625049 DOI: 10.1002/advs.202304553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/04/2023] [Indexed: 08/29/2023]
Abstract
The structurally related odd and even numbered wheels [FeIII 11 ZnII 4 (tea)10 (teaH)1 (OMe)Cl8 ] (1) and [FeIII 12 ZnII 4 (tea)12 Cl8 ] (2) can be synthesized under ambient conditions by reacting FeIII and ZnII salts with triethanolamine (teaH3 ), the change in nuclearity being dictated by the solvents employed. An antiferromagnetic exchange between nearest neighbors, J = -10.0 cm-1 for 1 and J = -12.0 cm-1 for 2, leads to a frustrated S = 1/2 ground state in the former and an S = 0 ground state in the latter.
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Affiliation(s)
- Daniel J. Cutler
- EaStCHEM School of ChemistryThe University of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
| | - Angelos B. Canaj
- EaStCHEM School of ChemistryThe University of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
| | - Mukesh K. Singh
- EaStCHEM School of ChemistryThe University of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
| | - Gary S. Nichol
- EaStCHEM School of ChemistryThe University of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
| | - David Gracia
- Instituto de Nanociencia y Materiales de Aragón (INMA)CSIC & Universidad de ZaragozaZaragoza50009Spain
| | - Hiroyuki Nojiri
- Institute for Materials ResearchTohoku UniversityKatahira 2‐1‐1Sendai980–8577Japan
| | - Marco Evangelisti
- Instituto de Nanociencia y Materiales de Aragón (INMA)CSIC & Universidad de ZaragozaZaragoza50009Spain
| | - Jürgen Schnack
- Universität Bielefeld | Fakultät für PhysikPostfach 100131D‐33501BielefeldGermany
| | - Euan K. Brechin
- EaStCHEM School of ChemistryThe University of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
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2
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Rubín J, Arauzo A, Bartolomé E, Sedona F, Rancan M, Armelao L, Luzón J, Guidi T, Garlatti E, Wilhelm F, Rogalev A, Amann A, Spagna S, Bartolomé J, Bartolomé F. Origin of the Unusual Ground-State Spin S = 9 in a Cr 10 Single-Molecule Magnet. J Am Chem Soc 2022; 144:12520-12535. [PMID: 35759747 PMCID: PMC9979690 DOI: 10.1021/jacs.2c05453] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The molecular wheel [Cr10(OMe)20(O2CCMe3)10], abbreviated {Cr10}, with an unusual intermediate total spin S = 9 and non-negligible cluster anisotropy, D/kB = -0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (S = 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr10}. For powder samples, the temperature dependence of the susceptibility plotted as χT(T) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve M(H) did not saturate at the expected 30 μB/fu for 10 FM coupled 3/2 spin Cr3+ ions, but to a much lower value, corresponding to S = 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 μB/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr10} wheel is formed by two semiwheels, each with four Cr3+ spins FM coupled (JFM/kB = 2.0 K), separated by two Cr3+ ions AF coupled asymmetrically (J23/kB = J78/kB = -2.0 K; J34/kB = J89/kB = -0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the S = 9 ground state and first excited S = 8. Single-molecule magnet behavior with an activation energy of U/kB = 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr10} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr-O-Cr alkoxy bridges coupling the Cr3+ ions, as demonstrated by ab initio and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr3+ ion in the wheel.
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Affiliation(s)
- Javier Rubín
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain,Departamento
de Ciencia y Tecnología de Materiales y Fluidos, Universidad de Zaragoza, 50018 Zaragoza, Spain,
| | - Ana Arauzo
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain,Servicio
de Medidas Físicas, Universidad de
Zaragoza, Pedro Cerbuna
12, 50009 Zaragoza, Spain,Departamento
de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Elena Bartolomé
- Escola
Universitària Salesiana de Sarrià (EUSS), Passeig Sant Joan Bosco 74, 08017 Barcelona, Spain,
| | - Francesco Sedona
- Dipartimento
di Scienze Chimiche, Università di
Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Marzio Rancan
- Institute
of Condensed Matter Chemistry and Technologies for Energy (ICMATE),
National Research Council (CNR), c/o Department of Chemistry, University of Padova, via F. Marzolo 1, 35131 Padova, Italy
| | - Lidia Armelao
- Dipartimento
di Scienze Chimiche, Università di
Padova, Via Marzolo 1, 35131 Padova, Italy,Department
of Chemical Sciences and Materials Technologies (DSCTM), National Research Council (CNR), Piazzale A. Moro 7, 00185 Roma, Italy
| | - Javier Luzón
- Academia
General Militar, Centro Universitario de
la Defensa, 50090 Zaragoza, Spain
| | - Tatiana Guidi
- Physics
Division, School of Science and Technology, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, MC, Italy,ISIS
Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, Oxfordshire, U.K.
| | - Elena Garlatti
- Dipartimento
di Science Matematiche, Fisiche e Informatiche, Università di Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy
| | - Fabrice Wilhelm
- ESRF − The European Synchrotron Radiation Facility, 71 Avenue des Martyrs CS40220, F-38043 Grenoble Cedex 09, France
| | - Andrei Rogalev
- ESRF − The European Synchrotron Radiation Facility, 71 Avenue des Martyrs CS40220, F-38043 Grenoble Cedex 09, France
| | - Andreas Amann
- Quantum Design Inc., San Diego, California 92121, United States
| | - Stefano Spagna
- Quantum Design Inc., San Diego, California 92121, United States
| | - Juan Bartolomé
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain,Departamento
de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Fernando Bartolomé
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain,Departamento
de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain,
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Magnetic Energy Landscape of Dimolybdenum Tetraacetate on a Bulk Insulator Surface. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11093806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The magnetic states and the magnetic anisotropy barrier of a transition metal molecular complex, dimolybdenum tetraacetate, are investigated via density functional theory (DFT). Calculations are performed in the gas phase and on a calcite (10.4) bulk insulating surface, using the Generalized-Gradient Approximation (GGA)-PBE and the Hubbard-corrected DFT + U and DFT + U + V functionals. The molecular complex (denoted MoMo) contains two central metallic molybdenum atoms, embedded in a square cage of acetate groups. Recently, MoMo was observed to form locally regular networks of immobile molecules on calcite (10.4), at room conditions. As this is the first example of a metal-coordinated molecule strongly anchored to an insulator surface at room temperature, we explore here its magnetic properties with the aim to understand whether the system could be assigned features of a single molecule magnet (SMM) and could represent the basis to realize stable magnetic networks on insulators. After an introductory review on SMMs, we show that, while the uncorrected GGA-PBE functional stabilizes MoMo in a nonmagnetic state, the DFT + U and DFT + U + V approaches stabilize an antiferromagnetic ground state and several meta-stable ferromagnetic and ferrimagnetic states. Importantly, the energy landscape of magnetic states remains almost unaltered on the insulating surface. Finally, via a noncollinear magnetic formalism and a newly introduced algorithm, we calculate the magnetic anisotropy barrier, whose value indicates the stability of the molecule’s magnetic moment.
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