1
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Keot N, Sarma M. Probing the dynamic behaviour and magnetic identification of seven coordinated Mn(II) complexes: a combined AIMD and multi-reference approach. Phys Chem Chem Phys 2023; 25:31165-31177. [PMID: 37953737 DOI: 10.1039/d3cp04072k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
We present an in-depth solution phase dynamics of rare seven coordinated pentagonal bipyramidal Mn(II) complexes, together with their binding affinity anticipated using ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT). Moreover, the simulations at different temperatures (25 °C and 90 °C) interpret the rigidity and stability of the ligands with Mn(II) ions. An intuitive approach for modulating the easy plane magnetic anisotropy of the mononuclear Mn(II) complex has been revealed by this work. In this regard, we have performed an extensive theoretical study based on the ab initio CASSCF/NEVPT2 method, exhibiting the presence of an easy plane magnetic anisotropy with a positive value of axial zero-field splitting (ZFS) parameter D. The complex's magnetic properties and electronic relaxation reveal that the rhombic ZFS term (E) can be modulated as the symmetry around the Mn(II) ion varies. The magnitude of the D-value increased with a more symmetrical equatorial ligand as found in the order of [Mn(pydpa)(H2O)] > [Mn(cbda)(H2O)]- > [Mn(dpaaa)(H2O)]- > [Mn(dpasam)(H2O)]-. Furthermore, we found that substituting the equatorial oxygen atom with heavier S and Se-donor atoms switches the sign of magnetic anisotropy for the Mn(II) complexes. The magnitude of the D-value increased when the energy levels of the ground state (GS) and the first excited state (ES) decreased. The observed magneto-structural correlation reveals that shortening the distance of the axial water molecule (Mn-O(w)) increases the D-value by an order of magnitude for the symmetrical [Mn(pydpa)(H2O)] complex. Overall, the combined analysis of solution phase dynamics of Mn(II) complexes and their magnetic characterization opens up new avenues in coordination chemistry, molecular magnetism, spin-crossover materials, and catalysis.
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Affiliation(s)
- Niharika Keot
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India.
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2
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Bruder F, Franzke YJ, Holzer C, Weigend F. Zero-field splitting parameters within exact two-component theory and modern density functional theory using seminumerical integration. J Chem Phys 2023; 159:194117. [PMID: 37987521 DOI: 10.1063/5.0175758] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 10/26/2023] [Indexed: 11/22/2023] Open
Abstract
An efficient implementation of zero-field splitting parameters based on the work of Schmitt et al. [J. Chem. Phys. 134, 194113 (2011)] is presented. Seminumerical integration techniques are used for the two-electron spin-dipole contribution and the response equations of the spin-orbit perturbation. The original formulation is further generalized. First, it is extended to meta-generalized gradient approximations and local hybrid functionals. For these functional classes, the response of the paramagnetic current density is considered in the coupled-perturbed Kohn-Sham equations for the spin-orbit perturbation term. Second, the spin-orbit perturbation is formulated within relativistic exact two-component theory and the screened nuclear spin-orbit (SNSO) approximation. The accuracy of the implementation is demonstrated for transition-metal and diatomic main-group compounds. The efficiency is assessed for Mn and Mo complexes. Here, it is found that coarse integration grids for the seminumerical schemes lead to drastic speedups while introducing clearly negligible errors. In addition, the SNSO approximation substantially reduces the computational demands and leads to very similar results as the spin-orbit mean field Ansatz.
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Affiliation(s)
- Florian Bruder
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Yannick J Franzke
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Christof Holzer
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1, 76131 Karlsruhe, Germany
| | - Florian Weigend
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
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3
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Silva Junior HC, Menezes HNS, Ferreira GB, Guedes GP. Rapid and Accurate Prediction of the Axial Magnetic Anisotropy in Cobalt(II) Complexes Using a Machine-Learning Approach. Inorg Chem 2023; 62:14838-14842. [PMID: 37676736 DOI: 10.1021/acs.inorgchem.3c02569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Estimating the magnetic anisotropy for single-ion magnets is complex due to its multireference nature. This study demonstrates that deep neural networks (DNNs) can provide accurate axial magnetic anisotropy (D) values, closely matching the complete-active-space self-consistent-field (CASSCF) quality using density functional theory (DFT) data. We curated an 86-parameter database (UFF1) with electronic data from over 33000 cobalt(II) compounds. The DNN achieved an R2 of 0.906 and a mean absolute error of 18.1 cm-1 in comparison to reference CASSCF D values. Remarkably, it is 11 times more accurate than DFT methods and 7700 times faster. This approach hints at DNNs predicting the anisotropy in larger molecules, even when trained on smaller ligands.
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Affiliation(s)
- Henrique C Silva Junior
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-141, Brazil
| | - Heloisa N S Menezes
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-141, Brazil
| | - Glaucio B Ferreira
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-141, Brazil
| | - Guilherme P Guedes
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-141, Brazil
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4
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Titiš J, Rajnák C, Boča R. Limitations on the D-Parameter in Ni(II) Complexes. J Phys Chem A 2023; 127:6412-6424. [PMID: 37494700 DOI: 10.1021/acs.jpca.3c02543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
A number of hexacoordinate, pentacoordinate, and tetracoordinate Ni(II) complexes have been investigated by applying ab initio CASSCF + NEVPT2 + SOC calculations and Generalized Crystal Field Theory. The geometry of the coordination polyhedron covers D4h, D3h, D2h, D2d, C4v, C3v, and C2v symmetry. The calculated spin-Hamiltonian parameters D and E were compared to the available experimental data. The limiting values of the D-parameter in the class of Ni(II) complexes are identified. Magnetic anisotropy in Ni(II) complexes, expressed by the axial zero-field splitting parameter D, seriously depends upon the ground and first excited electronic states. In hexacoordinate complexes, the ground electronic term is nondegenerate 3B1g for the D4h symmetry; D is slightly positive or negative. In tetracoordinate systems, D is only positive when the electronic ground state is nondegenerate 3A or 3B; this diverges on the τ4 path when oblate bisphenoid approaches the prolate geometry and a level crossing with 3E occurs. In pentacoordinate systems, D could be extremely negative when approaching a trigonal bipyramid (Addison index τ5 ∼ 1, ground state 3E″). In pentacoordinate Ni(II) complexes with the D3h and C3v symmetry of the coordination polyhedron, the ground electronic term is orbitally doubly degenerate which causes the D-parameter stays undefined. It is emphasized that one has to inspect compositions of the spin-orbit multiplets from the spin states |MS⟩ and check whether the weights confirm the expected spin-Hamiltonian picture: with D > 0, the ground state contains a dominant part of |0⟩ (close to 100%) whereas with D < 0 the spin-orbit doublet is formed of |±1⟩ with high weights (approaching 50 + 50%). The calculations show that the situations are not black and white, and the mixing of the states might be more complex especially when the rhombic zero-field splitting parameter E is in the play. In the case of the 3E ground term, six spin-orbit multiplets are formed by mixing six |MS⟩ states from the ground and quasi-degenerate excited states.
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Affiliation(s)
- Ján Titiš
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 91701 Trnava, Slovakia
| | - Cyril Rajnák
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 91701 Trnava, Slovakia
| | - Roman Boča
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 91701 Trnava, Slovakia
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5
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Georgiev M, Chamati H. Magnetic Behavior of Trigonal (Bi-)pyramidal 3d 8 Mononuclear Nanomagnets: The Case of [Ni(MDABCO) 2Cl 3]ClO 4. ACS OMEGA 2023; 8:28640-28650. [PMID: 37576657 PMCID: PMC10413474 DOI: 10.1021/acsomega.3c03208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 06/30/2023] [Indexed: 08/15/2023]
Abstract
This paper attempts to shed light on the origin of the magnetic behavior specific to trigonal bi- and pyramidal 3d8 mono- and polynuclear nanomagnets. The focus lies on entirely unraveling the system's intrinsic microscopic mechanisms and fundamental quantum mechanical relations governing the underlying electron dynamics. To this end, we develop a self-consistent approach to characterize, in great detail, all electron correlations and the ensuing fine structure of the energy spectra of a broad class of 3d8 systems. The mathematical framework is based on the multiconfigurational self-consistent field method and is devised to account for prospective quantum mechanical constraints that may confine the electron orbital dynamics while preserving the properties of all measurable quantities. We successfully characterize the experimentally observed magnetic anisotropy properties of a slightly distorted trigonal bipyramidal Ni2+ coordination complex, demonstrating that such compounds do not exhibit intrinsic huge zero-field splitting and inherent giant magnetic anisotropy. We reproduce qualitatively and quantitatively the behavior of the low-field magnetic susceptibility, magnetization, low-, and high-field electron paramagnetic resonance spectroscopy measurements and provide an in-depth analysis of the obtained results.
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Affiliation(s)
- Miroslav Georgiev
- Bulgarian Academy of Sciences, G Nadjakov Institute of Solid State Physics, Tsarigradsko Chaussée 72, 1784 Sofia, Bulgaria
| | - Hassan Chamati
- Bulgarian Academy of Sciences, G Nadjakov Institute of Solid State Physics, Tsarigradsko Chaussée 72, 1784 Sofia, Bulgaria
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6
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Maurice R, Mallah T, Guihéry N. Magnetism in Binuclear Compounds: Theoretical Insights. TOP ORGANOMETAL CHEM 2023. [DOI: 10.1007/3418_2022_78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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7
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Fine Structure and the Huge Zero-Field Splitting in Ni 2+ Complexes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27248887. [PMID: 36558020 PMCID: PMC9784865 DOI: 10.3390/molecules27248887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
We perform a thorough study of the ground state magnetic properties of nickel-based 3d8 complexes. This includes an in-depth analysis of the contribution of the crystal field, spin exchange and spin-orbit interactions to the ground state magnetic properties. Of particular interest to the current investigation are the presence and occurrence of non-trivial zero-field splitting. The study focuses on the cases of Ni2+ ideal octahedral, trigonal bipyramidal, square planar and tetrahedral geometries. We provide results for the complete energy spectrum, the fine structure related to the ground state and the second set of excited states, low-field magnetic susceptibility and magnetization. In addition, we examine the zero-field fine structure in square pyramidal, trigonal pyramidal and trigonal planar complexes. The obtained results unequivocally show that a moderate or highly coordinated 3d8 complex can neither exhibit spin-orbit-driven large and giant magnetic anisotropy nor a huge zero-field splitting. Moreover, in the trigonal bipyramidal coordination, a fine structure associated to the ground state cannot result from the spin-orbit coupling alone.
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8
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Georgiev M, Chamati H. Single-Ion Magnets with Giant Magnetic Anisotropy and Zero-Field Splitting. ACS OMEGA 2022; 7:42664-42673. [PMID: 36467950 PMCID: PMC9713882 DOI: 10.1021/acsomega.2c06119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
The design of mononuclear molecular nanomagnets exhibiting a huge energy barrier to the reversal of magnetization have seen a surge of interest during the last few decades due to their potential technological applications. More specifically, single-ion magnets are peculiarly attractive by virtue of their rich quantum behavior and distinct fine structure. These are viable candidates for implementation as single-molecule high-density information storage devices and other applications in future quantum technologies. The present review presents the comprehensive state of the art in the topic of single-ion magnets possessing an eminent magnetization-reversal barrier, very slow magnetic relaxation and high blocking temperature. We turn our attention to the achievements in the synthesis of 3d and 4f single-ion magnets during the last two decades and discuss the observed magnetostructural properties underlying the anisotropy behavior and the ensuing remanence. Furthermore, we highlight the fundamental theoretical aspects to shed light on the complex behavior of these nanosized magnetic entities. In particular, we focus on key notions, such as zero-field splitting, anisotropy energy and quantum tunneling of the magnetization and their interdependence.
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9
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Lunghi A, Sanvito S. Computational design of magnetic molecules and their environment using quantum chemistry, machine learning and multiscale simulations. Nat Rev Chem 2022; 6:761-781. [PMID: 37118096 DOI: 10.1038/s41570-022-00424-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2022] [Indexed: 11/09/2022]
Abstract
Having served as a playground for fundamental studies on the physics of d and f electrons for almost a century, magnetic molecules are now becoming increasingly important for technological applications, such as magnetic resonance, data storage, spintronics and quantum information. All of these applications require the preservation and control of spins in time, an ability hampered by the interaction with the environment, namely with other spins, conduction electrons, molecular vibrations and electromagnetic fields. Thus, the design of a novel magnetic molecule with tailored properties is a formidable task, which does not only concern its electronic structures but also calls for a deep understanding of the interaction among all the degrees of freedom at play. This Review describes how state-of-the-art ab initio computational methods, combined with data-driven approaches to materials modelling, can be integrated into a fully multiscale strategy capable of defining design rules for magnetic molecules.
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10
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Sauza-de la Vega A, Pandharkar R, Stroscio GD, Sarkar A, Truhlar DG, Gagliardi L. Multiconfiguration Pair-Density Functional Theory for Chromium(IV) Molecular Qubits. JACS AU 2022; 2:2029-2037. [PMID: 36186551 PMCID: PMC9516709 DOI: 10.1021/jacsau.2c00306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/19/2022] [Accepted: 08/19/2022] [Indexed: 05/30/2023]
Abstract
Pseudotetrahedral organometallic complexes containing chromium(IV) and aryl ligands have been experimentally identified as promising molecular qubit candidates. Here we present a computational protocol based on multiconfiguration pair-density functional theory for computing singlet-triplet gaps and zero-field splitting (ZFS) parameters in Cr(IV) aryl complexes. We find that two multireference methods, multistate complete active space second-order perturbation theory (MS-CASPT2) and hybrid multistate pair-density functional theory (HMS-PDFT), perform better than Kohn-Sham density functional theory for singlet-triplet gaps. Despite the very small values of the ZFS parameters, both multireference methods performed qualitatively well. MS-CASPT2 and HMS-PDFT performed particularly well for predicting the trend in the ratio of the rhombic and axial ZFS parameters, |E/D|. We have also investigated the dependence and sensitivity of the calculated ZFS parameters on the active space and the molecular geometry. The methodologies outlined here can guide future prediction of ZFS parameters in molecular qubit candidates.
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Affiliation(s)
- Arturo Sauza-de la Vega
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Riddhish Pandharkar
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
| | - Gautam D. Stroscio
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Arup Sarkar
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Donald G. Truhlar
- Department
of Chemistry, Chemical Theory Center, and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis, Minnesota 55455−0431, United States
| | - Laura Gagliardi
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
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11
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Wang Y, Li X. Unravelling the robustness of magnetic anisotropy of a nickelocene molecule in different environments: a first-principles-based study. Phys Chem Chem Phys 2022; 24:21122-21130. [PMID: 36039704 DOI: 10.1039/d2cp02793c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recent scanning tunneling spectroscopy with single metallocene molecule-functionalized tips have proved to be a powerful tool to probe and control individual spins and spin-spin exchange interactions due to the robustness of the magnetic properties of the metallocene molecule in different surroundings. However, accurate prediction of such robustness at a first-principles-based level by the conventional density functional theory (DFT) has remained challenging. In this paper, we have performed a detailed investigation of the evolution of electronic and magnetic properties of a nickelocene molecule (NiCp2) in different environments, i.e., free-standing, adsorbed on Cu(100) and as a functionalized tip apex. Using an embedding method, which combines DFT and the complete active space self-consistent field (CASSCF) method recently developed, we demonstrate that the nickelocene molecule almost preserves its spin and magnetic anisotropy upon adsorption on Cu(100), and also in the position of the tip apex. In particular, the cyclic π* orbital of the Cp rings could hybridize with the singly occupied dπ orbitals of the Ni center of the molecule, protecting these orbitals from external states. Hence the molecular spin maintains S = 1, the same as in the free-standing case, and its magnetic anisotropy is also robust with energies of 3.56, 3.34, and 3.51 meV in free-standing, adsorbed on Cu(100), and functionalized tip apex states, respectively, in good agreement with previous theoretical and experimental results. This work thus provides a first-principles-based understanding of the relevant experiments. Such agreement between theoretical simulations and experimental measurements highlights the potential usefulness of the method for investigating the local electronic and spin states of organometallic molecule-surface composite systems.
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Affiliation(s)
- Yu Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
| | - Xiaoguang Li
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
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12
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Bouammali MA, Suaud N, Guihéry N, Maurice R. Antisymmetric Exchange in a Real Copper Triangular Complex. Inorg Chem 2022; 61:12138-12148. [PMID: 35895313 DOI: 10.1021/acs.inorgchem.2c00939] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The antisymmetric exchange, also known as the Dzyaloshinskii-Moriya interaction (DMI), is an effective interaction that may be at play in isolated complexes (with transition metals or lanthanides, for instance), nanoparticles, and highly correlated materials with adequate symmetry properties. While many theoretical works have been devoted to the analysis of single-ion zero-field splitting and to a lesser extent to symmetric exchange, only a few ab initio studies deal with the DMI. Actually, it originates from a subtle interplay between weak electronic interactions and spin-orbit couplings. This article aims to highlight the origin of this interaction from theoretical grounds in a real tri-copper(II) complex, capitalizing on previous methodological studies on bi-copper(II) model complexes. By tackling this three-magnetic-center system, we will first show that the multispin model Hamiltonian is appropriate for trinuclear (and likely for higher nuclearity) complexes, then that the correct application of the permutation relationship is necessary to explain the outcomes of the ab initio calculations, and finally, that the model parameters extracted from a binuclear model transfer well to the trinuclear complex. For a more theory-oriented purpose, we will show that the use of a simplified structural model allows one to perform more demanding electronic structure calculations. On this simpler system, we will first check that the previous transferability is still valid, prior to performing more advanced calculations on the derived two-magnetic-center model system. To this end, we will explain in detail the physics of the DMI in the copper triangle of interest, before advocating further theory/experiment efforts.
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Affiliation(s)
- Mohammed-Amine Bouammali
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Nicolas Suaud
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Nathalie Guihéry
- Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 18 route de Narbonne, 31062 Toulouse, France
| | - Rémi Maurice
- SUBATECH, UMR CNRS 6457, IN2P3/IMT Atlantique/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3, France.,Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)─UMR 6226, 35000 Rennes, France
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13
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Amrutha K, Kathirvelu V. Interpretation of EPR and optical spectra of Ni(II) ions in crystalline lattices at ambient temperature. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:414-421. [PMID: 34859492 DOI: 10.1002/mrc.5237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 06/13/2023]
Abstract
Many biologically important paramagnetic metal ions are characterized by electron paramagnetic resonance (EPR) spectroscopy to use as spin probes to investigate the structure and function of biomolecules. Though nickel(II) ions are an essential trace element and part of many biomolecules, the EPR properties are least understood. Herein, the EPR and optical absorption spectra measured at 300 K for Ni(II) ions diluted in two different diamagnetic hosts are investigated and reported. The EPR spectrum of a polycrystalline Ni/Mg(3-methylpyrazole)6 (ClO4 )2 [Ni/MMPC] shows two transitions at X-band frequency (~9.5 GHz), suggesting the zero-field splitting parameter (D) is larger than the resonance field of the free electron (Ho ). This incomplete and complex spectrum is successfully analyzed to obtain EPR parameters. The EPR spectrum of the polycrystalline Ni/Zn(pyrazole)6 (NO3 )2 [Ni/ZPN] shows a triplet spectrum indicating D < Ho . A detailed analysis of single-crystal EPR data yielded the spin Hamiltonian parameters. The optical absorption spectra are deconvoluted to understand the symmetry of the coordination environment in the complex.
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Affiliation(s)
- Kamalon Amrutha
- Department of Applied Sciences, National Institute of Technology Goa, Ponda, India
| | - Velavan Kathirvelu
- Department of Applied Sciences, National Institute of Technology Goa, Ponda, India
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14
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Khedkar A, Roemelt M. Modern multireference methods and their application in transition metal chemistry. Phys Chem Chem Phys 2021; 23:17097-17112. [PMID: 34355719 DOI: 10.1039/d1cp02640b] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transition metal chemistry is a challenging playground for quantum chemical methods owing to the simultaneous presence of static and dynamic electron correlation effects in many systems. Wavefunction based multireference (MR) methods constitute a physically sound and systematically improvable Ansatz to deal with this complexity but suffer from some conceptual difficulties and high computational costs. The latter problem partially arises from the unfavorable scaling of the Full Configuration Interaction (Full-CI) problem which in the majority of MR methods is solved for a subset of the molecular orbital space, the so-called active space. In the last years multiple methods such as modern variants of selected CI, Full-CI Quantum Monte Carlo (FCIQMC) and the density matrix renormalization group (DMRG) have been developed that solve the Full-CI problem approximately for a fraction of the computational cost required by conventional techniques thereby significantly extending the range of applicability of modern MR methods. This perspective review outlines recent advancements in the field of MR electronic structure methods together with the resulting chances and challenges for theoretical studies in the field of transition metal chemistry. In light of its emerging importance a special focus is put on the selection of adequate active spaces and the concomitant development of numerous selection aides in recent years.
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Affiliation(s)
- Abhishek Khedkar
- Lehrstuhl für theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
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15
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Multireversible Redox Processes in a Self‐Assembled Nickel Pentanuclear Bis(Triple‐stranded Helicate): Structural and Spectroscopic Characterizations in the Ni
II
5
and Ni
I
Ni
II
4
Redox States. ChemElectroChem 2021. [DOI: 10.1002/celc.202100895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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16
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Abstract
Magnetic anisotropy, in the absence of an external magnetic field, relates to the degeneracy lift of energy levels. In the standard case of transition metal complexes, this property is usually modeled by an anisotropic spin Hamiltonian and one speaks of "zero-field splitting" (ZFS) of spin states. While the case of mononuclear complexes has been extensively described by means of ab initio quantum mechanical calculations, the literature on polynuclear complexes studied with these methodologies is rather scarce. In this work, advanced multiconfigurational wave function theory methods are applied to compute the ZFS of the ground S = 4 state of an actual tetranickel(II) complex, displaying a magnet behavior below 0.5 K. First, the isotropic couplings are computed in the absence of the spin-orbit coupling operator, in the full complex and also in clusters with only two active nickel(II) centers, confirming the occurrence of weak ferromagnetic couplings in this system. Second, the single-site magnetic anisotropies are computed on a cluster bearing only one active nickel(II) site, showing that the single-site anisotropy axes are not oriented in an optimal fashion for generating a large uniaxial molecular anisotropy. Furthermore, the possibility for involving only a few local orbital excited states in the calculation is assessed, actually opening the way for a consistent and manageable treatment of the ZFS of the ground S = 4 state. Third, multiconfigurational calculations are performed on the full complex, confirming the weak uniaxial anisotropy occurring for this state and also, interestingly, revealing a significant contribution of the lowest-lying orbitally excited S = 3 states. Overall, by comparison with the experiment, the reported results question the common habit of using only one structure, in particular derived from a crystallography experiment, to compute magnetic anisotropy parameters.
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Affiliation(s)
- Rémi Maurice
- SUBATECH, UMR CNRS 6457, IN2P3/IMT Atlantique/Université de Nantes, 4 rue A. Kastler, 44307 Nantes Cedex 3, France
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17
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Chiu CC, Cheng MC, Lin SH, Yan CW, Lee GH, Chang MC, Lin TS, Peng SM. Structure and magnetic properties of a novel heteroheptanuclear metal string complex [Ni 3Ru 2Ni 2(μ 7-teptra) 4(NCS) 2](PF 6). Dalton Trans 2020; 49:6635-6643. [PMID: 32367097 DOI: 10.1039/d0dt00156b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We report the synthesis of a novel heteroheptanuclear metal string complex (HMSC) [Ni3Ru2Ni2(μ7-teptra)4(NCS)2](PF6) 1 supported by tetra-pyridyl-tri-amine (H3teptra) ligands. We employed X-ray diffraction and other spectroscopic techniques to characterize the complex. The observed remarkably short Ru-Ru distance of 2.2499(3) Å for 1 is indicative of a unique metal-metal interaction in the mixed-valence [Ru2]5+ (S = 3/2) unit. The complex exhibits a relatively high magnetic moment value of 4.55 B.M. at 4 K, which increases rapidly to 6.00 B.M. at 30 K and remains at 6.11 B.M. from 50 to 300 K as shown by SQUID measurements, indicating a high spin (S≥ 3/2) system which is further supported by the analyses of EPR spectra at low temperatures. These magnetic behaviors can be ascribed to the result of spin-exchange interactions among multi-spin centers.
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Affiliation(s)
- Cheng-Chang Chiu
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., 10617 Taipei, Taiwan, Republic of China.
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18
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Kowalewski J, Fries PH, Kruk D, Odelius M, Egorov AV, Krämer S, Stork H, Horvatić M, Berthier C. Field-dependent paramagnetic relaxation enhancement in solutions of Ni(II): What happens above the NMR proton frequency of 1 GHz? JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 314:106737. [PMID: 32380383 DOI: 10.1016/j.jmr.2020.106737] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
An extended set of paramagnetic relaxation enhancement (PRE) data, up to the field of 32.9 Tesla, is reported for protons in an acidified aqueous solution of a Ni(II) salt in the presence and in the absence of added glycerol. For the 55% w/w glycerol sample, a distinct maximum in the PRE vs magnetic field curve is observed for the first time. The data are analysed using the Swedish slow-motion theory, including both the intramolecular (inner-sphere) and intermolecular (outer-sphere) contributions. The results indicate that estimating the outer-sphere part in the presence of the more efficient inner-sphere term is a difficult task.
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Affiliation(s)
- Jozef Kowalewski
- Department of Materials and Environmental Chemistry, Stockholm University, SE-116 91 Stockholm, Sweden.
| | - Pascal H Fries
- Univ. Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
| | - Danuta Kruk
- University of Warmia and Mazury in Olsztyn, Faculty of Mathematics and Computer Science, Sloneczna 54, PL-10710 Olsztyn, Poland
| | - Michael Odelius
- Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Andrei V Egorov
- St.Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Steffen Krämer
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Univ. Grenoble Alpes, INSA Toulouse, Univ. Toulouse Paul Sabatier, B.P. 166, 38042 Grenoble Cedex 09, France
| | - Holger Stork
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Univ. Grenoble Alpes, INSA Toulouse, Univ. Toulouse Paul Sabatier, B.P. 166, 38042 Grenoble Cedex 09, France
| | - Mladen Horvatić
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Univ. Grenoble Alpes, INSA Toulouse, Univ. Toulouse Paul Sabatier, B.P. 166, 38042 Grenoble Cedex 09, France
| | - Claude Berthier
- Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, Univ. Grenoble Alpes, INSA Toulouse, Univ. Toulouse Paul Sabatier, B.P. 166, 38042 Grenoble Cedex 09, France
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19
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Masys Š, Rinkevicius Z, Tamulienė J. On the magnetic properties of nanodiamonds: Electronic g-tensor calculations. J Chem Phys 2019; 151:044305. [PMID: 31370534 DOI: 10.1063/1.5111024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The electronic g-tensor calculations are carried out for various paramagnetic defects introduced into hydrogenated diamond nanocrystal C35H36, showing that such a system can be successfully used to model magnetic properties of nanodiamonds (NDs) with paramagnetic centers containing no vacancies. In addition, it is revealed that, depending on the geometric positions in ND, paramagnetic centers of the same type produce noticeable variations of the g-tensor values. A side-by-side comparison of the performance of effective nuclear charge and spin-orbit mean field (SOMF) approaches indicates that the latter is more sensitive to the quality of basis sets, especially concerning diffuse functions, the inclusion of which is found to be nonbeneficial. What is more, the SOMF method also exhibits a much more pronounced gauge-origin dependence. Compared to electronic charge centroid, spin centers (SCs) demonstrate a superior suitability as gauge origins, providing a better agreement with diamagnetic and paramagnetic contributions of g-tensor obtained employing gauge-including atomic orbitals (GIAOs). Therefore, SCs can be recommended for the g-tensor calculations of NDs whenever GIAOs are not available.
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Affiliation(s)
- Š Masys
- Institute of Theoretical Physics and Astronomy, Faculty of Physics, Vilnius University, LT-10257 Vilnius, Lithuania
| | - Z Rinkevicius
- Department of Theoretical Chemistry & Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - J Tamulienė
- Institute of Theoretical Physics and Astronomy, Faculty of Physics, Vilnius University, LT-10257 Vilnius, Lithuania
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20
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Roy Chowdhury S, Mishra S. Ab initioinvestigation of magnetic anisotropy in intermediate spin iron(iii) complexes. J Chem Phys 2018; 149:234302. [DOI: 10.1063/1.5050037] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Sabyashachi Mishra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India
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21
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Mareš J, Vaara J. Ab initio paramagnetic NMR shifts via point-dipole approximation in a large magnetic-anisotropy Co(ii) complex. Phys Chem Chem Phys 2018; 20:22547-22555. [PMID: 30141806 DOI: 10.1039/c8cp04123g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Transition metal complexes can possess a large magnetic susceptibility anisotropy, facilitating applications such as paramagnetic tags or shift agents in nuclear magnetic resonance (NMR) spectroscopy. Due to its g-shift and zero-field splitting (ZFS) we demonstrate on a Co(ii) clathrochelate with an aliphatic 16-carbon chain, a modern approach for ab initio calculation of paramagnetic susceptibility. Due to its large anisotropy, large linear dimension but relatively low number of atoms, the chosen complex is especially well-suited for testing the long-range point-dipole approximation (PDA) for the pseudocontact shifts (PCSs) of paramagnetic NMR. A static structure of the complex is used to compare the limiting long-distance PDA with full first-principles quantum-mechanical calculation. A non-symmetric formula for the magnetic susceptibility tensor is necessary to be consistent with the latter. Comparison with experimental shifts is performed by conformational averaging over the chain dynamics using Monte Carlo simulation. We observe satisfactory accuracy from the rudimentary simulation and, more importantly, demonstrate the fast applicability of the ab initio PDA.
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Affiliation(s)
- Jiří Mareš
- NMR Research Unit, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland.
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22
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Kamebuchi H, Sugaya T, Shiga R, Murakami H, Tadokoro M. Self-organized Tetranickel(II) Molecular Square with Imidazolinyl-imidazole Bridging Ligand. CHEM LETT 2018. [DOI: 10.1246/cl.180218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Hajime Kamebuchi
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Tomoaki Sugaya
- Education Center, Faculty of Engineering, Chiba Institute of Technology, 2-1-1 Shibazono, Narashino, Chiba 275-0023, Japan
| | - Ryosuke Shiga
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Hiroki Murakami
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Makoto Tadokoro
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
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23
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Khan S, Peters V, Kowalewski J, Odelius M. Zero-field splitting in the isoelectronic aqueous Gd(III) and Eu(II) complexes from a first principles analysis. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Gupta T, Rajaraman G. Modelling spin Hamiltonian parameters of molecular nanomagnets. Chem Commun (Camb) 2018; 52:8972-9008. [PMID: 27366794 DOI: 10.1039/c6cc01251e] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular nanomagnets encompass a wide range of coordination complexes possessing several potential applications. A formidable challenge in realizing these potential applications lies in controlling the magnetic properties of these clusters. Microscopic spin Hamiltonian (SH) parameters describe the magnetic properties of these clusters, and viable ways to control these SH parameters are highly desirable. Computational tools play a proactive role in this area, where SH parameters such as isotropic exchange interaction (J), anisotropic exchange interaction (Jx, Jy, Jz), double exchange interaction (B), zero-field splitting parameters (D, E) and g-tensors can be computed reliably using X-ray structures. In this feature article, we have attempted to provide a holistic view of the modelling of these SH parameters of molecular magnets. The determination of J includes various class of molecules, from di- and polynuclear Mn complexes to the {3d-Gd}, {Gd-Gd} and {Gd-2p} class of complexes. The estimation of anisotropic exchange coupling includes the exchange between an isotropic metal ion and an orbitally degenerate 3d/4d/5d metal ion. The double-exchange section contains some illustrative examples of mixed valance systems, and the section on the estimation of zfs parameters covers some mononuclear transition metal complexes possessing very large axial zfs parameters. The section on the computation of g-anisotropy exclusively covers studies on mononuclear Dy(III) and Er(III) single-ion magnets. The examples depicted in this article clearly illustrate that computational tools not only aid in interpreting and rationalizing the observed magnetic properties but possess the potential to predict new generation MNMs.
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Affiliation(s)
- Tulika Gupta
- Department of Chemistry, IIT Powai, Mumbai-400076, India.
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25
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Naveed KUR, Wang L, Yu H, Ullah RS, Haroon M, Fahad S, Li J, Elshaarani T, Khan RU, Nazir A. Recent progress in the electron paramagnetic resonance study of polymers. Polym Chem 2018. [DOI: 10.1039/c8py00689j] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This review article provides an overview of the contemporary research based on a tailor-made technique to understand the paramagnetic behavior of different polymer classes.
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Affiliation(s)
| | - Li Wang
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Haojie Yu
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Raja Summe Ullah
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Muhammad Haroon
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Shah Fahad
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Jiyang Li
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Tarig Elshaarani
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Rizwan Ullah Khan
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
| | - Ahsan Nazir
- College of Chemical and Biological Engineering
- Zhejiang University
- Zhejiang
- China
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26
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Mondal A, Gaultois MW, Pell AJ, Iannuzzi M, Grey CP, Hutter J, Kaupp M. Large-Scale Computation of Nuclear Magnetic Resonance Shifts for Paramagnetic Solids Using CP2K. J Chem Theory Comput 2017; 14:377-394. [DOI: 10.1021/acs.jctc.7b00991] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Arobendo Mondal
- Institut
für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekretariat C7, Strasse des 17 Juni 135, D-10623 Berlin, Germany
| | - Michael W. Gaultois
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Andrew J. Pell
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Marcella Iannuzzi
- Institut
für Chemie, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Clare P. Grey
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Jürg Hutter
- Institut
für Chemie, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Martin Kaupp
- Institut
für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekretariat C7, Strasse des 17 Juni 135, D-10623 Berlin, Germany
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27
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Lu J, Ozel IO, Belvin CA, Li X, Skorupskii G, Sun L, Ofori-Okai BK, Dincă M, Gedik N, Nelson KA. Rapid and precise determination of zero-field splittings by terahertz time-domain electron paramagnetic resonance spectroscopy. Chem Sci 2017; 8:7312-7323. [PMID: 29163882 PMCID: PMC5672788 DOI: 10.1039/c7sc00830a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/10/2017] [Indexed: 01/09/2023] Open
Abstract
Zero-field splitting (ZFS) parameters are fundamentally tied to the geometries of metal ion complexes. Despite their critical importance for understanding the magnetism and spectroscopy of metal complexes, they are not routinely available through general laboratory-based techniques, and are often inferred from magnetism data. Here we demonstrate a simple tabletop experimental approach that enables direct and reliable determination of ZFS parameters in the terahertz (THz) regime. We report time-domain measurements of electron paramagnetic resonance (EPR) signals associated with THz-frequency ZFSs in molecular complexes containing high-spin transition-metal ions. We measure the temporal profiles of the free-induction decays of spin resonances in the complexes at zero and nonzero external magnetic fields, and we derive the EPR spectra via numerical Fourier transformation of the time-domain signals. In most cases, absolute values of the ZFS parameters are extracted from the measured zero-field EPR frequencies, and the signs can be determined by zero-field measurements at two different temperatures. Field-dependent EPR measurements further allow refined determination of the ZFS parameters and access to the g-factor. The results show good agreement with those obtained by other methods. The simplicity of the method portends wide applicability in chemistry, biology and material science.
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Affiliation(s)
- Jian Lu
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - I Ozge Ozel
- Department of Physics , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA
| | - Carina A Belvin
- Department of Physics , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA
| | - Xian Li
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - Grigorii Skorupskii
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - Lei Sun
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - Benjamin K Ofori-Okai
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - Mircea Dincă
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
| | - Nuh Gedik
- Department of Physics , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA
| | - Keith A Nelson
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , USA .
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28
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Rouf SA, Jakobsen VB, Mareš J, Jensen ND, McKenzie CJ, Vaara J, Nielsen UG. Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 87:29-37. [PMID: 28759801 DOI: 10.1016/j.ssnmr.2017.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 06/07/2023]
Abstract
Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)2L2] with L = H2O, D2O, NH3, ND3, and PMe2Ph have provided detailed insight into the origin of the paramagnetic contributions to the total shift tensor. This was employed for the assignment of the solid-state 1,2H and 13C MAS NMR spectra of these compounds. The two major contributions to the isotropic shifts are by orbital (diamagnetic-like) and contact mechanism. The orbital shielding, contact, as well as dipolar terms all contribute to the anisotropic component. The calculations suggest reassignment of the 13C methyl and carbonyl resonances in the acac ligand [Inorg. Chem.53, 2014, 399] leading to isotropic paramagnetic shifts of δ(13C) ≈ 800-1100 ppm and ≈180-300 ppm for 13C for the methyl and carbonyl carbons located three and two bonds away from the paramagnetic Ni(II) ion, respectively. Assignment using three different empirical correlations, i.e., paramagnetic shifts, shift anisotropy, and relaxation (T1) were ambiguous, however the latter two support the computational results. Thus, solid-state NMR spectroscopy in combination with modern quantum-chemical calculations of paramagnetic shifts constitutes a promising tool for structural investigations of metal complexes and materials.
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Affiliation(s)
- Syed Awais Rouf
- NMR Research Unit, University of Oulu, P.O. BOX 3000, FIN-90014 Oulu, Finland
| | - Vibe Boel Jakobsen
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark; School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jiří Mareš
- NMR Research Unit, University of Oulu, P.O. BOX 3000, FIN-90014 Oulu, Finland
| | - Nicholai Daugaard Jensen
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - Christine J McKenzie
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - Juha Vaara
- NMR Research Unit, University of Oulu, P.O. BOX 3000, FIN-90014 Oulu, Finland
| | - Ulla Gro Nielsen
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark.
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29
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Mansikkamäki A, Popov AA, Deng Q, Iwahara N, Chibotaru LF. Interplay of spin-dependent delocalization and magnetic anisotropy in the ground and excited states of [Gd 2@C 78] - and [Gd 2@C 80] . J Chem Phys 2017; 147:124305. [PMID: 28964020 DOI: 10.1063/1.5004183] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The magnetic properties and electronic structure of the ground and excited states of two recently characterized endohedral metallo-fullerenes, [Gd2@C78]- (1) and [Gd2@C80]- (2), have been studied by theoretical methods. The systems can be considered as [Gd2]5+ dimers encapsulated in a fullerene cage with the fifteen unpaired electrons ferromagnetically coupled into an S = 15/2 high-spin configuration in the ground state. The microscopic mechanisms governing the Gd-Gd interactions leading to the ferromagnetic ground state are examined by a combination of density functional and ab initio calculations and the full energy spectrum of the ground and lowest excited states is constructed by means of ab initio model Hamiltonians. The ground state is characterized by strong electron delocalization bordering on a σ type one-electron covalent bond and minor zero-field splitting (ZFS) that is successfully described as a second order spin-orbit coupling effect. We have shown that the observed ferromagnetic interaction originates from Hund's rule coupling and not from the conventional double exchange mechanism. The calculated ZFS parameters of 1 and 2 in their optimized geometries are in qualitative agreement with experimental EPR results. The higher excited states display less electron delocalization, but at the same time they possess unquenched first-order angular momentum. This leads to strong spin-orbit coupling and highly anisotropic energy spectrum. The analysis of the excited states presented here constitutes the first detailed study of the effects of spin-dependent delocalization in the presence of first order orbital angular momentum and the obtained results can be applied to other mixed valence lanthanide systems.
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Affiliation(s)
- Akseli Mansikkamäki
- Theory of Nanomaterials Group, Chemistry Department, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Alexey A Popov
- Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, Dresden 01069, Germany
| | - Qingming Deng
- Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, Dresden 01069, Germany
| | - Naoya Iwahara
- Theory of Nanomaterials Group, Chemistry Department, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Liviu F Chibotaru
- Theory of Nanomaterials Group, Chemistry Department, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
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30
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Ravera E, Parigi G, Luchinat C. Perspectives on paramagnetic NMR from a life sciences infrastructure. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 282:154-169. [PMID: 28844254 DOI: 10.1016/j.jmr.2017.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 05/17/2023]
Abstract
The effects arising in NMR spectroscopy because of the presence of unpaired electrons, collectively referred to as "paramagnetic NMR" have attracted increasing attention over the last decades. From the standpoint of the structural and mechanistic biology, paramagnetic NMR provides long range restraints that can be used to assess the accuracy of crystal structures in solution and to improve them by simultaneous refinements through NMR and X-ray data. These restraints also provide information on structure rearrangements and conformational variability in biomolecular systems. Theoretical improvements in quantum chemistry calculations can nowadays allow for accurate calculations of the paramagnetic data from a molecular structural model, thus providing a tool to refine the metal coordination environment by matching the paramagnetic effects observed far away from the metal. Furthermore, the availability of an improved technology (higher fields and faster magic angle spinning) has promoted paramagnetic NMR applications in the fast-growing area of biomolecular solid-state NMR. Major improvements in dynamic nuclear polarization have been recently achieved, especially through the exploitation of the Overhauser effect occurring through the contact-driven relaxation mechanism: the very large enhancement of the 13C signal observed in a variety of liquid organic compounds at high fields is expected to open up new perspectives for applications of solution NMR.
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Affiliation(s)
- Enrico Ravera
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, via Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, via Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Claudio Luchinat
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, via Sacconi 6, 50019 Sesto Fiorentino, Italy.
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31
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Sugisaki K, Toyota K, Sato K, Shiomi D, Takui T. Behaviour of DFT-based approaches to the spin–orbit term of zero-field splitting tensors: a case study of metallocomplexes, MIII(acac)3 (M = V, Cr, Mn, Fe and Mo). Phys Chem Chem Phys 2017; 19:30128-30138. [DOI: 10.1039/c7cp05533a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Zero-field splitting tensors of MIII(acac)3 complexes are calculated using ab initio and DFT methods.
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Affiliation(s)
- Kenji Sugisaki
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University
- Sumiyoshi-ku
- Japan
| | - Kazuo Toyota
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University
- Sumiyoshi-ku
- Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University
- Sumiyoshi-ku
- Japan
| | - Daisuke Shiomi
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University
- Sumiyoshi-ku
- Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University
- Sumiyoshi-ku
- Japan
- Research Support/URA Centre, University Administration Department, Osaka City University
- Sumiyoshi-ku
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32
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Sugisaki K, Toyota K, Sato K, Shiomi D, Takui T. Quasi-Restricted Orbital Treatment for the Density Functional Theory Calculations of the Spin–Orbit Term of Zero-Field Splitting Tensors. J Phys Chem A 2016; 120:9857-9866. [DOI: 10.1021/acs.jpca.6b10253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Kenji Sugisaki
- Department of Chemistry and
Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan
| | - Kazuo Toyota
- Department of Chemistry and
Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan
| | - Kazunobu Sato
- Department of Chemistry and
Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan
| | - Daisuke Shiomi
- Department of Chemistry and
Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan
| | - Takeji Takui
- Department of Chemistry and
Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan
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33
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Insights into the value of statistical models and relativistic effects for the investigation of halogenated derivatives of fluorescent probes. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1862-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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34
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Pradipto AM, Broer R, Picozzi S. Ab initio modelling of magnetic anisotropy in Sr3NiPtO6. Phys Chem Chem Phys 2016; 18:4078-85. [PMID: 26778078 DOI: 10.1039/c5cp05954b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
First principles calculations in the framework of Density Functional Theory (DFT) and wavefunction-based correlated methods have been performed to investigate in detail the magnetic anisotropy in Sr3NiPtO6. This material is known for the easy-plane anisotropy with a large anisotropy constant of about 7.5-9.3 meV. We find that by properly choosing the onsite Coulomb repulsion and exchange parameters, DFT can correctly explain the easy-plane magnetocrystalline anisotropy of the material, but the magnitude of the anisotropy constant is underestimated. On the other hand, a quantitative agreement with respect to experiments, both in the magnitude and direction of the magnetic anisotropy, can be recovered by using the wavefunction-based approach which is able to fully describe the multiplet physics. We also show that the presence of structural distortions of the local NiO6 coordination is crucial for stabilizing the magnetic anisotropy in this compound.
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Affiliation(s)
- A-M Pradipto
- Consiglio Nazionale delle Ricerche - CNR-SPIN, I-66100 Chieti, Italy.
| | - R Broer
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands.
| | - S Picozzi
- Consiglio Nazionale delle Ricerche - CNR-SPIN, I-66100 Chieti, Italy.
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35
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Zlatar M, Gruden M, Vassilyeva OY, Buvaylo EA, Ponomarev AN, Zvyagin SA, Wosnitza J, Krzystek J, Garcia-Fernandez P, Duboc C. Origin of the Zero-Field Splitting in Mononuclear Octahedral Mn(IV) Complexes: A Combined Experimental and Theoretical Investigation. Inorg Chem 2016; 55:1192-201. [PMID: 26745448 DOI: 10.1021/acs.inorgchem.5b02368] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this work was to determine and understand the origin of the electronic properties of Mn(IV) complexes, especially the zero-field splitting (ZFS), through a combined experimental and theoretical investigation on five well-characterized mononuclear octahedral Mn(IV) compounds, with various coordination spheres (N6, N3O3, N2O4 in both trans (trans-N2O4) and cis configurations (cis-N2O4) and O4S2). High-frequency and -field EPR (HFEPR) spectroscopy has been applied to determine the ZFS parameters of two of these compounds, MnL(trans-N2O4) and MnL(O4S2). While at X-band EPR, the axial-component of the ZFS tensor, D, was estimated to be +0.47 cm(-1) for MnL(O4S2), and a D-value of +2.289(5) cm(-1) was determined by HFEPR, which is the largest D-magnitude ever measured for a Mn(IV) complex. A moderate D value of -0.997(6) cm(-1) has been found for MnL(trans-N2O4). Quantum chemical calculations based on two theoretical frameworks (the Density Functional Theory based on a coupled perturbed approach (CP-DFT) and the hybrid Ligand-Field DFT (LF-DFT)) have been performed to define appropriate methodologies to calculate the ZFS tensor for Mn(IV) centers, to predict the orientation of the magnetic axes with respect to the molecular ones, and to define and quantify the physical origin of the different contributions to the ZFS. Except in the case of MnL(trans-N2O4), the experimental and calculated D values are in good agreement, and the sign of D is well predicted, LF-DFT being more satisfactory than CP-DFT. The calculations performed on MnL(cis-N2O4) are consistent with the orientation of the principal anisotropic axis determined by single-crystal EPR, validating the calculated ZFS tensor orientation. The different contributions to D were analyzed demonstrating that the d-d transitions mainly govern D in Mn(IV) ion. However, a deep analysis evidences that many factors enter into the game, explaining why no obvious magnetostructural correlations can be drawn in this series of Mn(IV) complexes.
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Affiliation(s)
- Matija Zlatar
- Center for Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade , Njegoševa 12, P.O. Box 815, 11001 Belgrade, Serbia
| | - Maja Gruden
- Faculty of Chemistry, University of Belgrade , Studentski trg 12-16, 11001 Belgrade, Serbia
| | - Olga Yu Vassilyeva
- Department of Chemistry, Taras Shevchenko National University of Kyiv , 64/13 Volodymyrska str., Kyiv 01601, Ukraine
| | - Elena A Buvaylo
- Department of Chemistry, Taras Shevchenko National University of Kyiv , 64/13 Volodymyrska str., Kyiv 01601, Ukraine
| | - A N Ponomarev
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Saxony, Germany
| | - S A Zvyagin
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Saxony, Germany
| | - J Wosnitza
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Saxony, Germany.,Institut für Festkörperphysik, Technische Universität Dresden , D-01062 Dresden, Saxony, Germany
| | - J Krzystek
- National High Magnetic Field Laboratory (NHMFL), Florida State University , Tallahassee, Florida 32310, United States
| | - Pablo Garcia-Fernandez
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria , Avenida de los Castros s/n, 39005 Santander, Cantabria, Spain
| | - Carole Duboc
- Département de Chimie Moléculaire, Université Grenoble Alpes/CNRS, UMR-5250 , BP-53, 38041 Grenoble Cedex 9, France
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36
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37
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Brazzolotto D, Gennari M, Yu S, Pécaut J, Rouzières M, Clérac R, Orio M, Duboc C. An Experimental and Theoretical Investigation on Pentacoordinated Cobalt(III) Complexes with an Intermediate S=
1 Spin State: How Halide Ligands Affect their Magnetic Anisotropy. Chemistry 2015; 22:925-33. [DOI: 10.1002/chem.201502997] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 11/06/2022]
Affiliation(s)
| | | | - Shengying Yu
- Univ. Grenoble Alpes, DCM, CNRS UMR 5250; 38000 Grenoble France
| | - Jacques Pécaut
- Univ. Grenoble Alpes, CEA, INAC-SCIB; 38000 Grenoble France
| | - Mathieu Rouzières
- CNRS, CRPP, UPR 8641; F-33600 Pessac France
- Univ. Bordeaux, CRPP, UPR 8641; F-33600 Pessac France
| | - Rodolphe Clérac
- CNRS, CRPP, UPR 8641; F-33600 Pessac France
- Univ. Bordeaux, CRPP, UPR 8641; F-33600 Pessac France
| | - Maylis Orio
- Aix Marseille Université, ISM2, CNRS UMR 7313; 13397 Marseille France
| | - Carole Duboc
- Univ. Grenoble Alpes, DCM, CNRS UMR 5250; 38000 Grenoble France
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38
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Vaara J, Rouf SA, Mareš J. Magnetic couplings in the chemical shift of paramagnetic NMR. J Chem Theory Comput 2015; 11:4840-9. [PMID: 26574272 DOI: 10.1021/acs.jctc.5b00656] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We apply the Kurland-McGarvey (J. Magn. Reson. 1970, 2, 286) theory for the NMR shielding of paramagnetic molecules, particularly its special case limited to the ground-state multiplet characterized by zero-field splitting (ZFS) interaction of the form S·D·S. The correct formulation for this problem was recently presented by Soncini and Van den Heuvel (J. Chem. Phys. 2013, 138, 054113). With the effective electron spin quantum number S, the theory involves 2S+1 states, of which all but one are low-lying excited states, between which magnetic couplings take place by Zeeman and hyperfine interactions. We investigate these couplings as a function of temperature, focusing on both the high- and low-temperature behaviors. As has been seen in work by others, the full treatment of magnetic couplings is crucial for a realistic description of the temperature behavior of NMR shielding up to normal measurement temperatures. At high temperatures, depending on the magnitude of ZFS, the effect of magnetic couplings diminishes, and the Zeeman and hyperfine interactions become effectively averaged in the thermally occupied states of the multiplet. At still higher temperatures, the ZFS may be omitted altogether, and the shielding properties may be evaluated using a doublet-like formula, with all the 2S+1 states becoming effectively degenerate at the limit of vanishing magnetic field. We demonstrate these features using first-principles calculations of Ni(II), Co(II), Cr(II), and Cr(III) complexes, which have ZFS of different sizes and signs. A non-monotonic inverse temperature dependence of the hyperfine shift is predicted for axially symmetric integer-spin systems with a positive D parameter of ZFS. This is due to the magnetic coupling terms that are proportional to kT at low temperatures, canceling the Curie-type 1/kT prefactor of the hyperfine shielding in this case.
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Affiliation(s)
- Juha Vaara
- NMR Research Group, University of Oulu , P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Syed Awais Rouf
- NMR Research Group, University of Oulu , P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Jiří Mareš
- NMR Research Group, University of Oulu , P.O. Box 3000, FIN-90014 Oulu, Finland
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39
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Rouf SA, Mareš J, Vaara J. 1H Chemical Shifts in Paramagnetic Co(II) Pyrazolylborate Complexes: A First-Principles Study. J Chem Theory Comput 2015; 11:1683-91. [DOI: 10.1021/acs.jctc.5b00193] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Syed Awais Rouf
- NMR Research Group, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Jiří Mareš
- NMR Research Group, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Juha Vaara
- NMR Research Group, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
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40
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Khan S, Kubica-Misztal A, Kruk D, Kowalewski J, Odelius M. Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches. J Chem Phys 2015; 142:034304. [DOI: 10.1063/1.4905559] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Shehryar Khan
- Department of Physics, Stockholm University, AlbaNova University Center, S-106 91 Stockholm, Sweden
| | | | - Danuta Kruk
- Faculty of Mathematics and Computer Science, University of Warmia and Mazury in Olsztyn, Sloneczna 54, Olsztyn PL-10710, Poland
| | - Jozef Kowalewski
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - Michael Odelius
- Department of Physics, Stockholm University, AlbaNova University Center, S-106 91 Stockholm, Sweden
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41
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Yoe F, Flores-Alamo M, Morales F, Escudero R, Cortes-Hernández H, Castro M, Barba-Behrens N. Structural, magnetic and theoretical study of mononuclear nickel(II) and cobalt(II) compounds of a benzimidazole thiobutanoic acid derivative. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.07.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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42
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Singh SK, Gupta T, Badkur P, Rajaraman G. Magnetic anisotropy of mononuclear Ni(II) complexes: on the importance of structural diversity and the structural distortions. Chemistry 2014; 20:10305-13. [PMID: 25042299 DOI: 10.1002/chem.201402694] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Indexed: 11/06/2022]
Abstract
Mononuclear Ni(II) complexes are particularly attractive in the area of single-molecule magnets as the axial zero-field splitting (D) for the Ni(II) complexes is in the range of -200 to +200 cm(-1) . Despite this advantage, very little is known on the origin of anisotropy across various coordination ligands, coordination numbers, and particularly what factors influence the D parameter in these complexes. To answer some of these questions, herein we have undertaken a detailed study of a series of mononuclear Ni(II) complexes with ab initio calculations. Our results demonstrate that three prominent spin-conserved low-lying d-d transitions contribute significantly to the D value. Variation in the sign and the magnitude of D values are found to correlate to the specific structural distortions. Apart from the metal-ligand bond lengths, two different parameters, namely, Δα and Δβ, which are correlated to the cis angles present in the coordination environment, are found to significantly influence the axial D values. Developed magneto-structural D correlations suggest that the D values can be enhanced significantly by fine tuning the structural distortion in the coordination environment. Calculations performed on a series of Ni(II) models with coordination numbers two to six unfold an interesting observation-the D parameter increases significantly upon a reduction in coordination number compared with a reference octahedral coordination. Besides, if high symmetry is maintained, even larger coordination numbers yield large D values.
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Affiliation(s)
- Saurabh Kumar Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai,Mumbai,Maharashtra,India-400 076, Fax: (+91) 22-2576-7152
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43
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Rantaharju J, Mareš J, Vaara J. Spin dynamics simulation of electron spin relaxation in Ni2 +(aq). J Chem Phys 2014; 141:014109. [DOI: 10.1063/1.4885050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Jyrki Rantaharju
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland
| | - Jiří Mareš
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland
| | - Juha Vaara
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland
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44
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Lasoroski A, Vuilleumier R, Pollet R. Vibrational dynamics of zero-field-splitting hamiltonian in gadolinium-based MRI contrast agents from ab initio molecular dynamics. J Chem Phys 2014; 141:014201. [DOI: 10.1063/1.4885848] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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45
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Sugisaki K, Toyota K, Sato K, Shiomi D, Kitagawa M, Takui T. An ab initio MO study of heavy atom effects on the zero-field splitting tensors of high-spin nitrenes: how the spin–orbit contributions are affected. Phys Chem Chem Phys 2014; 16:9171-81. [DOI: 10.1039/c4cp00822g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The CASSCF and hybrid CASSCF–MRMP2 methods reproduce the ZFS tensors of spin-septet 2,4,6-trinitrenopyridines, focusing on the heavy atom effects on the spin–orbit terms of the tensors.
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Affiliation(s)
- Kenji Sugisaki
- Department of Chemistry
- Graduate School of Science
- Osaka City University
- Osaka 558-8585, Japan
| | - Kazuo Toyota
- Department of Chemistry
- Graduate School of Science
- Osaka City University
- Osaka 558-8585, Japan
| | - Kazunobu Sato
- Department of Chemistry
- Graduate School of Science
- Osaka City University
- Osaka 558-8585, Japan
| | - Daisuke Shiomi
- Department of Chemistry
- Graduate School of Science
- Osaka City University
- Osaka 558-8585, Japan
| | - Masahiro Kitagawa
- Department of System Innovation
- Graduate School of Engineering Science
- Osaka University
- Osaka 560-8531, Japan
| | - Takeji Takui
- Department of Chemistry
- Graduate School of Science
- Osaka City University
- Osaka 558-8585, Japan
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46
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Mareš J, Hanni M, Lantto P, Lounila J, Vaara J. Curie-type paramagnetic NMR relaxation in the aqueous solution of Ni(ii). Phys Chem Chem Phys 2014; 16:6916-24. [DOI: 10.1039/c3cp55522d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The magnetic field of the Curie spin manifests itself as both the pNMR shielding tensor and Curie relaxation, in analogy with CSA relaxation theory.
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Affiliation(s)
- Jiří Mareš
- NMR Research Group
- Department of Physics
- University of Oulu
- Oulu, Finland
| | - Matti Hanni
- NMR Research Group
- Department of Physics
- University of Oulu
- Oulu, Finland
- Department of Radiology
| | - Perttu Lantto
- NMR Research Group
- Department of Physics
- University of Oulu
- Oulu, Finland
| | - Juhani Lounila
- NMR Research Group
- Department of Physics
- University of Oulu
- Oulu, Finland
| | - Juha Vaara
- NMR Research Group
- Department of Physics
- University of Oulu
- Oulu, Finland
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47
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Maurice R, Verma P, Zadrozny JM, Luo S, Borycz J, Long JR, Truhlar DG, Gagliardi L. Single-Ion Magnetic Anisotropy and Isotropic Magnetic Couplings in the Metal–Organic Framework Fe2(dobdc). Inorg Chem 2013; 52:9379-89. [DOI: 10.1021/ic400953e] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Rémi Maurice
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Pragya Verma
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Joseph M. Zadrozny
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Sijie Luo
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Joshua Borycz
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Jeffrey R. Long
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Donald G. Truhlar
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Laura Gagliardi
- Department of Chemistry, Supercomputing Institute, and Chemical Theory
Center, University of Minnesota, Minneapolis,
Minnesota 55455, United States
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48
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Maurice R, Graaf CD, Guihéry N. Theoretical determination of spin Hamiltonians with isotropic and anisotropic magnetic interactions in transition metal and lanthanide complexes. Phys Chem Chem Phys 2013; 15:18784-804. [DOI: 10.1039/c3cp52521j] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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49
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Chemical Shift in Paramagnetic Systems. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-444-59411-2.00003-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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