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Hand AT, Watson-Sanders BD, Xue ZL. Spectroscopic techniques to probe magnetic anisotropy and spin-phonon coupling in metal complexes. Dalton Trans 2024; 53:4390-4405. [PMID: 38380640 DOI: 10.1039/d3dt03609j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Magnetism of molecular quantum materials such as single-molecule magnets (SMMs) has been actively studied for potential applications in the new generation of high-density data storage using SMMs and quantum information science. Magnetic anisotropy and spin-phonon coupling are two key properties of d- and f-metal complexes. Here, phonons refer to both intermolecular and intramolecular vibrations. Direct determination of magnetic anisotropy and experimental studies of spin-phonon coupling are critical to the understanding of molecular magnetism. This article discusses our recent approach in using three complementary techniques, far-IR and Raman magneto-spectroscopies (FIRMS and RaMS, respectively) and inelastic neutron scatterings (INS), to determine magnetic excited states. Spin-phonon couplings are observed in FIRMS and RaMS. DFT phonon calculations give energies and symmetries of phonons as well as calculated INS spectra which help identify magnetic peaks in experimental INS spectra.
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Affiliation(s)
- Adam T Hand
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
| | | | - Zi-Ling Xue
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Larsen EMH, Bonde NA, Weihe H, Ollivier J, Vosch T, Lohmiller T, Holldack K, Schnegg A, Perfetti M, Bendix J. Experimental assignment of long-range magnetic communication through Pd & Pt metallophilic contacts. Chem Sci 2023; 14:266-276. [PMID: 36687355 PMCID: PMC9811497 DOI: 10.1039/d2sc05201f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/21/2022] [Indexed: 11/23/2022] Open
Abstract
Record-breaking magnetic exchange interactions have previously been reported for 3d-metal dimers of the form [M(Pt(SAc)4)(pyNO2)]2 (M = Ni or Co) that are linked in the solid state via metallophilic Pt⋯Pt bridges. This contrasts the terminally capped monomers [M(Pt(SAc)4)(py)2], for which neither metallophilic bridges nor magnetic exchange interactions are found. Computational modeling has shown that the magnetic exchange interaction is facilitated by the pseudo-closed shell d8⋯d8 metallophilic interaction between the filled Pt2+ 5d z 2 orbitals. We present here inelastic neutron scattering experiments on these complexes, wherein the dimers present an oscillatory momentum-transfer-dependence of the magnetic transitions. This allows for the unequivocal experimental assignment of the distance between the coupled ions, which matches exactly the coupling pathway via the metallophilic bridges. Furthermore, we have synthesized and magnetically characterized the isostructural palladium-analogues. The magnetic coupling across the Pd⋯Pd bridge is found through SQUID-magnetometry and FD-FT THz-EPR spectroscopy to be much weaker than via the Pt⋯Pt bridge. The weaker coupling is traced to the larger radial extent of the 5d z 2 orbitals compared to that of the 4d z 2 orbitals. The existence of a palladium metallophilic interaction is evaluated computationally from potential surface cuts along the metal stretching direction. Similar behavior is found for the Pd⋯Pd and Pt⋯Pt-systems with clear minima along this coordinate and provide estimates for the force constant for this distortion. The estimated M⋯M stretching frequencies are found to match experimental observed, polarized bands in single-crystal Raman spectra close to 45 cm-1. This substantiates the existence of energetically relevant Pd⋯Pd metallophilic interactions. The unique properties of both Pt2+ and Pd2+ constitutes an orthogonal reactivity, which can be utilized for steering both the direction and strength of magnetic interactions.
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Affiliation(s)
- Emil M. H. Larsen
- Department of Chemistry, University of CopenhagenUniversitetsparken 5DK-2100 CopenhagenDenmark
| | - Niels A. Bonde
- Department of Chemistry, University of CopenhagenUniversitetsparken 5DK-2100 CopenhagenDenmark,Institut Laue-Langevin71 avenue des MartyrsCS 2015638042 Grenoble Cedex 9France
| | - Høgni Weihe
- Department of Chemistry, University of CopenhagenUniversitetsparken 5DK-2100 CopenhagenDenmark
| | - Jacques Ollivier
- Institut Laue-Langevin71 avenue des MartyrsCS 2015638042 Grenoble Cedex 9France
| | - Tom Vosch
- Department of Chemistry, University of CopenhagenUniversitetsparken 5DK-2100 CopenhagenDenmark
| | - Thomas Lohmiller
- Humboldt-Universität zu Berlin, Institut für ChemieBrook-Taylor-Str. 212489 BerlinGermany,EPR4 Energy Joint Lab, Department Spins in Energy Conversion and Quantum Information Science, Helmholtz Zentrum Berlin für Materialien und Energie GmbHAlbert-Einstein-Straße 1512489 BerlinGermany
| | - Karsten Holldack
- Department of Optics and Beamlines, Helmholtz Zentrum Berlin für Materialien und Energie GmbHAlbert-Einstein-Straße 1512489 BerlinGermany
| | - Alexander Schnegg
- EPR4 Energy Joint Lab, Department Spins in Energy Conversion and Quantum Information Science, Helmholtz Zentrum Berlin für Materialien und Energie GmbHAlbert-Einstein-Straße 1512489 BerlinGermany,Max Planck Institute for Chemical Energy ConversionStiftstrasse 34-36D-45470 Mülheim an der RuhrGermany
| | - Mauro Perfetti
- Department of Chemistry “U. Schiff”, University of FlorenceVia della Lastruccia 3-13, Sesto Fiorentino50019Italy
| | - Jesper Bendix
- Department of Chemistry, University of CopenhagenUniversitetsparken 5DK-2100 CopenhagenDenmark
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Moseley DH, Liu Z, Bone AN, Stavretis SE, Singh SK, Atanasov M, Lu Z, Ozerov M, Thirunavukkuarasu K, Cheng Y, Daemen LL, Lubert-Perquel D, Smirnov D, Neese F, Ramirez-Cuesta AJ, Hill S, Dunbar KR, Xue ZL. Comprehensive Studies of Magnetic Transitions and Spin-Phonon Couplings in the Tetrahedral Cobalt Complex Co(AsPh 3) 2I 2. Inorg Chem 2022; 61:17123-17136. [PMID: 36264658 DOI: 10.1021/acs.inorgchem.2c02604] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combination of inelastic neutron scattering (INS), far-IR magneto-spectroscopy (FIRMS), and Raman magneto-spectroscopy (RaMS) has been used to comprehensively probe magnetic excitations in Co(AsPh3)2I2 (1), a reported single-molecule magnet (SMM). With applied field, the magnetic zero-field splitting (ZFS) peak (2D') shifts to higher energies in each spectroscopy. INS placed the ZFS peak at 54 cm-1, as revealed by both variable-temperature (VT) and variable-magnetic-field data, giving results that agree well with those from both far-IR and Raman studies. Both FIRMS and RaMS also reveal the presence of multiple spin-phonon couplings as avoided crossings with neighboring phonons. Here, phonons refer to both intramolecular and lattice vibrations. The results constitute a rare case in which the spin-phonon couplings are observed with both Raman-active (g modes) and far-IR-active phonons (u modes; space group P21/c, no. 14, Z = 4 for 1). These couplings are fit using a simple avoided crossing model with coupling constants of ca. 1-2 cm-1. The combined spectroscopies accurately determine the magnetic excited level and the interaction of the magnetic excitation with phonon modes. Density functional theory (DFT) phonon calculations compare well with INS, allowing for the assignment of the modes and their symmetries. Electronic calculations elucidate the nature of ZFS in the complex. Features of different techniques to determine ZFS and other spin-Hamiltonian parameters in transition-metal complexes are summarized.
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Affiliation(s)
- Duncan H Moseley
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Zhiming Liu
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Alexandria N Bone
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Shelby E Stavretis
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Saurabh Kumar Singh
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, 502285Sangareddy, Telangana, India
| | - Mihail Atanasov
- Max Planck Institute for Coal Research, Kaiser-Wilhelm-Platz 1, D-45470Mülheim an der Ruhr, Germany.,Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113Sofia, Bulgaria
| | - Zhengguang Lu
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | | | - Yongqiang Cheng
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Luke L Daemen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Daphné Lubert-Perquel
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | - Frank Neese
- Max Planck Institute for Coal Research, Kaiser-Wilhelm-Platz 1, D-45470Mülheim an der Ruhr, Germany
| | - A J Ramirez-Cuesta
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Stephen Hill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States.,Department of Physics, Florida State University, Tallahassee, Florida32306, United States
| | - Kim R Dunbar
- Department of Chemistry, Texas A&M University, College Station, Texas77843, United States
| | - Zi-Ling Xue
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
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