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Borah A, Dey S, Siddiqui K, Gupta SK, Rajaraman G, Murugavel R. Magnetic anisotropy in octahedral Dy(III) and Yb(III) complexes. Dalton Trans 2024; 53:7263-7267. [PMID: 38618749 DOI: 10.1039/d3dt04352e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
New organophosphate complexes [Ln(dippH)3(dippH2)3]·(H2O)6, (Ln = Dy, Yb and Y; dippH2 = 2,6-diisopropylphenyl phosphate), displaying octahedral coordination geometry around the metal ion, exhibit unusual slow relaxation of magnetisation, which is investigated through experimental studies and ab initio CASSCF calculations.
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Affiliation(s)
- Aditya Borah
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400076, India.
- Department of Chemistry, Jengraimukh College, Majuli, Assam, 785105, India
| | - Sourav Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400076, India.
| | - Kehkasha Siddiqui
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400076, India.
| | - Sandeep K Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, Delhi, 110016, India
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400076, India.
| | - Ramaswamy Murugavel
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400076, India.
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Ray D, Oakley MS, Sarkar A, Bai X, Gagliardi L. Theoretical Investigation of Single-Molecule-Magnet Behavior in Mononuclear Dysprosium and Californium Complexes. Inorg Chem 2023; 62:1649-1658. [PMID: 36652606 PMCID: PMC9890484 DOI: 10.1021/acs.inorgchem.2c04013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Early-actinide-based (U, Np, and Pu) single-molecule magnets (SMMs) have yet to show magnetic properties similar to those of highly anisotropic lanthanide-based ones. However, there are not many studies exploring the late-actinides (more than half-filled f shells) as potential candidates for SMM applications. We computationally explored the electronic structure and magnetic properties of a hypothetical Cf(III) complex isostructural to the experimentally synthesized Dy(dbm)3(bpy) complex (bpy = 2,2'-bipyridine; dbm = dibenzoylmethanoate) via multireference methods and compared them to those of the Dy(III) analogue. This study shows that the Cf(III) complex can behave as a SMM and has a greater magnetic susceptibility compared to other experimentally and computationally studied early-actinide-based (U, Np, and Pu) magnetic complexes. However, Cf spontaneously undergoes α-decay and converts to Cm. Thus, we also explored the isostructural Cm(III)-based complex. The computed magnetic susceptibility and g-tensor values show that the Cm(III) complex has poor SMM behavior in comparison to both the Dy(III) and Cf(III) complexes, suggesting that the performance of Cf(III)-based magnets may be affected by α-decay and can explain the poor performance of experimentally studied Cf(III)-based molecular magnets in the literature. Further, this study suggests that the ligand field is dominant in Cf(III), which helps to increase the magnetization blocking barrier by nearly 3 times that of its 4f congener.
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Affiliation(s)
- Debmalya Ray
- Department
of Chemistry, Chemical Theory Center, and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Meagan S. Oakley
- Department
of Chemistry, Chemical Theory Center, and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Arup Sarkar
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, The University of Chicago, Chicago, Illinois60637, United States
| | - Xiaojing Bai
- Department
of Chemistry, Chemical Theory Center, and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Laura Gagliardi
- Department
of Chemistry, Pritzker School of Molecular Engineering, James Franck
Institute, Chicago Center for Theoretical Chemistry, The University of Chicago, Chicago, Illinois60637, United States,
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Dey S, Rajaraman G. In silico design criteria for high blocking barrier uranium (III) SIMs. Chem Commun (Camb) 2022; 58:6817-6820. [PMID: 35615940 DOI: 10.1039/d2cc01356h] [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
A combination of DFT and ab initio CASSCF/PT2 calculations on U(III) fictitious models and numerous reported X-ray structures unveils several geometries from coordination number 1 to 12 that can be targeted to design potential U(III) SIMs with attractive barrier heights. Among the geometries studied, the T-shaped and capped pentagonal antiprism geometries yield values exceeding 1500 cm-1 - a value that is elusive for any uranium SIMs.
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Affiliation(s)
- Sourav Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
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Dey S, Rajaraman G. Deciphering the Role of Symmetry and Ligand Field in Designing Three-Coordinate Uranium and Plutonium Single-Molecule Magnets. Inorg Chem 2022; 61:1831-1842. [PMID: 35025497 DOI: 10.1021/acs.inorgchem.1c02646] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Actinide single-molecule magnets (SMMs) have gained paramount interest in molecular magnetism as they offer a larger barrier height of magnetization (Ueff) reversal compared to the lanthanide analogue, thanks to their greater metal-ligand covalency. However, the reported actinide SMMs to date yield a relatively smaller Ueff as there is no established design principle to enhance Ueff values. To address this issue, we have employed ab initio CASSCF/CASPT2/NEVPT2 calculations to study a series of three-coordinate U3+ and Pu3+ SMMs. To begin with, we have studied two experimentally characterized U3+ ion-field-induced SMMs, namely, planar [U{N(SiMe2tBu)2}3] (1) and pyramidal [U{N(SiMe3)2}3] (2) complexes reported earlier. Both the complexes were found to stabilize mJ = |±1/2⟩ as the ground state with a very strong quantum tunneling of magnetization (QTM), rendering them unsuitable for SMMs. Our calculations reveal that in the pyramidal geometry (such as in 2), the energy of the 5f26d1 state is lowered compared to the planar geometry (as in 1), resulting in a slightly better SMM characteristic in the former. To unravel the effect of symmetry in magnetic properties, ab initio calculations were performed on two reported T-shaped complexes [U(NSiiPr2)2(I)] (3) and [U(NHAriPr6)2I] (4, AriPr6 = 2,6-(2,4,6-iPr3C6H2)2C6H3). Quite interestingly, mJ = |±9/2⟩ is found to be the ground state for both the complexes with a blocking barrier exceeding 900 cm-1. Furthermore, to decipher the effect of the transuranic element in magnetic anisotropy, ab initio calculations were extended to the Pu analogue of 2, [Pu{N(SiMe3)2}3] (5), which yields a record-breaking blocking barrier of ∼1933 cm-1. Among the three-coordinate geometries studied, the pyramidal geometry was found to offer substantial magnetic anisotropy for Pu3+ ions, while a T-shaped geometry is best suited for U3+ ions. While the chosen theoretical protocols' overestimation of barrier height cannot be avoided, these values are still several orders of magnitude larger than the Ueff values reported for any actinide SMMs and unveil a design principle for superior three-coordinate actinide-based SMMs.
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Affiliation(s)
- Sourav Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Abstract
Molecular magnets are a relatively new class of purely organic or metallo-organic materials, showing magnetism even without an external magnetic field. This interdisciplinary field between chemistry and physics has been gaining increased interest since the 1990s. While bulk molecular magnets are usually hard to build because of their molecular structures, low-dimensional molecular magnets are often easier to construct, down to dot-like (zero-dimensional) structures, which are investigated by different scanning probe technologies. On these scales, new effects such as superparamagnetic behavior or coherent switching during magnetization reversal can be recognized. Here, we give an overview of the recent advances in molecular nanomagnets, starting with single-molecule magnets (0D), typically based on Mn12, Fe8, or Mn4, going further to single-chain magnets (1D) and finally higher-dimensional molecular nanomagnets. This review does not aim to give a comprehensive overview of all research fields dealing with molecular nanomagnets, but instead aims at pointing out diverse possible materials and effects in order to stimulate new research in this broad field of nanomagnetism.
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Borah A, Dey S, Gupta SK, Walawalkar MG, Rajaraman G, Murugavel R. Enhancing the barrier height for Yb(III) single-ion magnets by modulating axial ligand fields. Chem Commun (Camb) 2020; 56:11879-11882. [PMID: 33021294 DOI: 10.1039/d0cc01370f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The effect of systematic modification of the axial ligand field X on Ueff values in Yb(iii)-based SIMs, [Yb(Ph3PO)4X2]X' (X, X' = NO3 (1), OTf (2) and X = I/Br/Cl; X' = I3 (3)), whose equatorial Ph3PO ligation remains unchanged, has been investigated. Combined magnetic studies coupled with ab initio calculations reveal weakening of the axial ligand fields leading to the increase in the energy barrier, apart from suggesting the operation of different relaxation pathways.
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Affiliation(s)
- Aditya Borah
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India.
| | - Sourav Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India.
| | - Sandeep K Gupta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India.
| | | | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India.
| | - Ramaswamy Murugavel
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India.
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Apostolidis C, Kovács A, Walter O, Colineau E, Griveau J, Morgenstern A, Rebizant J, Caciuffo R, Panak PJ, Rabung T, Schimmelpfennig B, Perfetti M. Tris-{hydridotris(1-pyrazolyl)borato}actinide Complexes: Synthesis, Spectroscopy, Crystal Structure, Bonding Properties and Magnetic Behaviour. Chemistry 2020; 26:11293-11306. [PMID: 32519790 PMCID: PMC7497007 DOI: 10.1002/chem.202001095] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/26/2020] [Indexed: 01/10/2023]
Abstract
The isostructural compounds of the trivalent actinides uranium, neptunium, plutonium, americium, and curium with the hydridotris(1-pyrazolyl)borato (Tp) ligand An[η3 -HB(N2 C3 H3 )3 ]3 (AnTp3 ) have been obtained through several synthetic routes. Structural, spectroscopic (absorption, infrared, laser fluorescence) and magnetic characterisation of the compounds were performed in combination with crystal field, density functional theory (DFT) and relativistic multiconfigurational calculations. The covalent bonding interactions were analysed in terms of the natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) models.
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Affiliation(s)
| | - Attila Kovács
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | - Olaf Walter
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | - Eric Colineau
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | | | - Alfred Morgenstern
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | - Jean Rebizant
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | - Roberto Caciuffo
- European Commission, Joint Research CentrePostfach 234076125KarlsruheGermany
| | - Petra J. Panak
- Institut für Nukleare EntsorgungForschungszentrum KarlsruhePostfach 364076021KarlsruheGermany
| | - Thomas Rabung
- Institut für Nukleare EntsorgungForschungszentrum KarlsruhePostfach 364076021KarlsruheGermany
| | - Bernd Schimmelpfennig
- Institut für Nukleare EntsorgungForschungszentrum KarlsruhePostfach 364076021KarlsruheGermany
| | - Mauro Perfetti
- Department of ChemistryUniversity of CopenhagenUniversitetsparken 52100CopenhagenDenmark
- Department of Chemistry “Ugo Schiff” and INSTM Research UnitUniversity of FlorenceVia della Lastruccia 350019Sesto FiorentinoItaly
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Kalita P, Ahmed N, Bar AK, Dey S, Jana A, Rajaraman G, Sutter JP, Chandrasekhar V. Pentagonal Bipyramidal Ln(III) Complexes Containing an Axial Phosphine Oxide Ligand: Field-induced Single-ion Magnetism Behavior of the Dy(III) Analogues. Inorg Chem 2020; 59:6603-6612. [PMID: 32309926 DOI: 10.1021/acs.inorgchem.0c00751] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A series of neutral homologous complexes [(L)Ln(Cy3PO)Cl] {where Ln = Gd (1), Tb (2), Dy (3), and Er (5)} and [(L)Dy(Ph3PO)Cl] (4) [H2L = 2,6-diacetylpyridine bis-benzoylhydrazone] were isolated. In these complexes, the central lanthanide ion possesses a pentagonal bipyramidal geometry with an overall pseudo D5h symmetry. The coordination environment around the lanthanide ion comprises of three nitrogen and two oxygen donors in an equatorial plane. The axial positions are taken up by a phosphine oxide (O donor) and a chloride ion. Among these compounds, the Dy(III) (3 and 4) analogues were found to be field-induced single-ion magnets.
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Affiliation(s)
- Pankaj Kalita
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India.,Tata Institute of Fundamental Research Hyderabad, Gopanpally 500107, Hyderabad, India
| | - Naushad Ahmed
- Tata Institute of Fundamental Research Hyderabad, Gopanpally 500107, Hyderabad, India
| | - Arun Kumar Bar
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India
| | - Sourav Dey
- Departrment of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally 500107, Hyderabad, India
| | - Gopalan Rajaraman
- Departrment of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Jean-Pascal Sutter
- Laboratoire de Chimie de Coordination du CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research Hyderabad, Gopanpally 500107, Hyderabad, India.,Department of Chemistry, IIT Kanpur, Kanpur 208016, India
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Autillo M, Islam MA, Jung J, Pilmé J, Galland N, Guerin L, Moisy P, Berthon C, Tamain C, Bolvin H. Crystallographic structure and crystal field parameters in the [AnIV(DPA)3]2− series, An = Th, U, Np, Pu. Phys Chem Chem Phys 2020; 22:14293-14308. [DOI: 10.1039/d0cp02137g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The [AnIV(DPA)3]2− series with An = Th, U, Np, Pu has been synthesized and characterized using SC-XRD, vibrational spectroscopy, and first principles calculations.
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Affiliation(s)
| | - Md. Ashraful Islam
- Laboratoire de Chimie et Physique Quantiques
- CNRS
- Université Toulouse III
- 31062 Toulouse
- France
| | - Julie Jung
- Theoretical division
- Los Alamos National Laboratory
- Los Alamos
- USA
| | - Julien Pilmé
- Sorbonne Université
- CNRS
- Laboratoire de Chimie Théorique CC 137-4 place Jussieu
- 75252 Paris Cédex 05
- France
| | | | | | | | | | | | - Hélène Bolvin
- Laboratoire de Chimie et Physique Quantiques
- CNRS
- Université Toulouse III
- 31062 Toulouse
- France
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