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Bokouende SS, Ward CL, Allen MJ. Understanding the Coordination Chemistry and Structural and Photophysical Properties of Eu II- and Sm II-Containing Complexes of Hexamethylhexacyclen and Noncyclic Tetradentate Amines. Inorg Chem 2024; 63:16991-17004. [PMID: 39238155 DOI: 10.1021/acs.inorgchem.4c02590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2024]
Abstract
Ligands play a crucial role in supporting or stabilizing the divalent oxidation state of lanthanide metals. To expand the range of ligands used to chelate divalent lanthanide ions, we synthesized and studied the structural and photophysical properties of complexes of EuII and SmII with hexamethylhexacyclen, 1,1,4,7,10,10-hexamethyltriethylenetetramine, tris[2-(dimethylamino)ethyl]amine, and tris[2-(isopropylamino)ethyl]amine as supporting ligands. Coordination of hexamethylhexacyclen, an analogue of 18-crown-6, generates sterically crowded complexes of EuII and SmII that are either seven or eight coordinate and adopt a range of geometries that differ from those of their 18-crown-6 counterparts and from those of lanthanide-containing complexes with the acyclic tetradente tertiary amine ligands included in this report. The emission spectra of EuII(hexamethylhexacyclen) show a moderate sensitivity to counterion identity and are more red-shifted compared to those of complexes of EuII with 18-crown-6 and the hexamethylated aza derivative of 2.2.2-cryptand. In addition, the morphology of hexamethylhexacyclen in [LnI(hexamethylhexacyclen)]I was found to resemble that of thermally stable alkalides of the form [M(hexamethylhexacyclen)]Na- (M = K+ or Cs+), suggesting that hexamethylhexacyclen could be an interesting ligand for strongly reducing lanthanide ions.
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Affiliation(s)
| | - Cassandra L Ward
- Lumigen Instrument Center, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202, United States
| | - Matthew J Allen
- Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202, United States
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2
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Delano F, Benner F, Jang S, Greer SM, Demir S. Construction of intermolecular σ-hole interactions in rare earth metallocene complexes using a 2,3,4,5-tetraiodopyrrolyl anion. Chem Sci 2024; 15:13389-13404. [PMID: 39183902 PMCID: PMC11339973 DOI: 10.1039/d4sc03786c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Accepted: 06/29/2024] [Indexed: 08/27/2024] Open
Abstract
The generation of noncovalent intermolecular interactions represents a powerful method to control molecular vibrations and rotations. Combining these with the axial ligand field enforced by the metallocene ligand scaffold provides a dual-pronged approach in controlling the magnetic-relaxation pathways for dysprosium-based single-molecule magnets (SMMs). Here, we present the first implementation of 2,3,4,5-tetraiodopyrrole (TIPH) in its anionic form [TIP]- as a ligand in three isostructural rare-earth metal complexes Cp*2RE(TIP) (1-RE, RE = Y, Gd, and Dy; Cp* = pentamethylcylopentadienyl), where the TIP ligand binds through the nitrogen and one iodine atom κ2(N,I) to the metal centre. The shallow potential energy surface of the intermolecular σ-hole interaction yields distortions of the interatomic distances at elevated temperatures which were investigated by variable-temperature SCXRD. 1-RE constitute the first crystallographically characterized molecules containing TIP as a ligand for any metal ion, and 1-Dy is the first SMM that employs the TIP ligand. The structural dependence on temperature allowed the mechanism of magnetic relaxation to be explored through ab initio calculations at different temperatures. The electronic influence of the coordinated iodine substituent was probed via magnetometry and cw-EPR spectroscopy on 1-Gd. To further scrutinize the impact of the iodine substituents on the physical properties, a second set of new complexes Cp*2RE(DMP) (2-RE, RE = Y, and Dy) where DMP = 2,5-dimethylpyrrolyl were synthesized. Here, the DMP ligand binds similarly to the TIP ligand and represents an all-hydrocarbon analogue to 1-RE. 2-Dy constitutes the first SMM bearing a DMP ligand.
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Affiliation(s)
- Francis Delano
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - Florian Benner
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - Seoyun Jang
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - Samuel M Greer
- Los Alamos National Laboratory (LANL) Los Alamos New Mexico 87545 USA
| | - Selvan Demir
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
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MacKenzie RE, Hajdu T, Seed JA, Whitehead GFS, Adams RW, Chilton NF, Collison D, McInnes EJL, Goodwin CAP. δ-Bonding modulates the electronic structure of formally divalent nd 1 rare earth arene complexes. Chem Sci 2024:d4sc03005b. [PMID: 39220159 PMCID: PMC11361033 DOI: 10.1039/d4sc03005b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 07/28/2024] [Indexed: 09/04/2024] Open
Abstract
Landmark advances in rare earth (RE) chemistry have shown that divalent complexes can be isolated with non-Aufbau 4f n {5d/6s}1 electron configurations, facilitating remarkable bonding motifs and magnetic properties. We report a series of divalent bis-tethered arene complexes, [RE(NHAriPr6 )2] (2RE; RE = Sc, Y, La, Sm, Eu, Tm, Yb; NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}). Fluid solution EPR spectroscopy gives g iso < 2.002 for 2Sc, 2Y, and 2La, consistent with formal nd1 configurations, calculations reveal metal-arene δ-bonding via mixing of nd(x 2-y 2) valence electrons into arene π* orbitals. Experimental and calculated EPR and UV-Vis-NIR spectroscopic properties for 2Y show that minor structural changes markedly alter the metal d(x 2-y 2) contribution to the SOMO. This contrasts 4f n {5d/6s}1 complexes where the valence d-based electron resides in a non-bonding orbital. Complexes 2Sm, 2Eu, 2Tm, and 2Yb contain highly-localised 4f n+1 ions with no appreciable metal-arene bonding by density functional calculations. These results show that the physicochemical properties of divalent rare earth arene complexes with both formal nd1 and 4f n+1 configurations are nuanced, may be controlled through ligand modification, and require a multi-pronged experimental and theoretical approach to fully rationalise.
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Affiliation(s)
- Ross E MacKenzie
- Centre for Radiochemistry Research, The University of Manchester Oxford Road Manchester M13 9PL UK
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Tomáš Hajdu
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
- Photon Science Institute, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - John A Seed
- Centre for Radiochemistry Research, The University of Manchester Oxford Road Manchester M13 9PL UK
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - George F S Whitehead
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Ralph W Adams
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Nicholas F Chilton
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
- Research School of Chemistry, The Australian National University Sullivans Creek Road Canberra 2601 Australia
| | - David Collison
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
- Photon Science Institute, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Eric J L McInnes
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
- Photon Science Institute, The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Conrad A P Goodwin
- Centre for Radiochemistry Research, The University of Manchester Oxford Road Manchester M13 9PL UK
- Department of Chemistry, The University of Manchester Oxford Road Manchester M13 9PL UK
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Deng W, Wu SG, Ruan ZY, Gong YP, Du SN, Wang HL, Chen YC, Zhang WX, Liu JL, Tong ML. Spin-State Control in Dysprosium(III) Metallacrown Magnets via Thioacetal Modification. Angew Chem Int Ed Engl 2024; 63:e202404271. [PMID: 38700507 DOI: 10.1002/anie.202404271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Indexed: 06/19/2024]
Abstract
Integrating controllable spin states into single-molecule magnets (SMMs) enables precise manipulation of magnetic interactions at a molecular level, but remains a synthetic challenge. Herein, we developed a 3d-4f metallacrown (MC) magnet [DyNi5(quinha)5(Clsal)2(py)8](ClO4) ⋅ 4H2O (H2quinha=quinaldichydroxamic acid, HClsal=5-chlorosalicylaldehyde) wherein a square planar NiII is stabilized by chemical stacking. Thioacetal modification was employed via post-synthetic ligand substitutions and yielded [DyNi5(quinha)5(Clsaldt)2(py)8](ClO4) ⋅ 3H2O (HClsaldt=4-chloro-2-(1,3-dithiolan-2-yl)phenol). Thanks to the additional ligations of thioacetal onto the NiII site, coordination-induced spin state switching (CISSS) took place with spin state altering from low-spin S=0 to high-spin S=1. The synergy of CISSS effect and magnetic interactions results in distinct energy splitting and magnetic dynamics. Magnetic studies indicate prominent enhancement of reversal barrier from 57 cm-1 to 423 cm-1, along with hysteresis opening and an over 200-fold increment in coercive field at 2 K. Ab initio calculations provide deeper insights into the exchange models and rationalize the relaxation/tunnelling pathways. These results demonstrate here provide a fire-new perspective in modulating the magnetization relaxation via the incorporation of controllable spin states and magnetic interactions facilitated by the CISSS approach.
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Affiliation(s)
- Wei Deng
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Si-Guo Wu
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Ze-Yu Ruan
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Ya-Ping Gong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Shan-Nan Du
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Hai-Ling Wang
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Yan-Cong Chen
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Wei-Xiong Zhang
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Jun-Liang Liu
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Ming-Liang Tong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
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Xin J, Hu Z, Yao YR, Ullah A, Han X, Xiang W, Jin H, Jiang Z, Yang S. Short Didysprosium Covalent Bond Enables High Magnetization Blocking Temperature of a Direct 4f-4f Coupled Dinuclear Single-Molecule Magnet. J Am Chem Soc 2024; 146:17600-17605. [PMID: 38869355 DOI: 10.1021/jacs.4c04429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Coupling two magnetic anisotropic lanthanide ions via a direct covalent bond is an effective way to realize high magnetization blocking temperature of single-molecule magnets (SMMs) by suppressing quantum tunneling of magnetization (QTM), whereas so far only single-electron lanthanide-lanthanide bonds with relatively large bond distances are stabilized in which coupling between lanthanide and the single electron dominates over weak direct 4f-4f coupling. Herein, we report for the first time synthesis of short Dy(II)-Dy(II) single bond (3.61 Å) confined inside a carbon cage in the form of an endohedral metallofullerene Dy2@C82. Such a direct Dy(II)-Dy(II) covalent bond renders a strong Dy-Dy antiferromagnetic coupling that effectively quenches QTM at zero magnetic field, thus opening up magnetic hysteresis up to 25 K using a field sweep rate of 25 Oe/s, concomitant with a high 100 s magnetization blocking temperature (TB,100s) of 27.2 K.
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Affiliation(s)
- Jinpeng Xin
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Ziqi Hu
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Yang-Rong Yao
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Aman Ullah
- Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Xinyi Han
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Wenhao Xiang
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Huaimin Jin
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Zhanxin Jiang
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Shangfeng Yang
- Key Laboratory of Precision and Intelligent Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
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6
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Delano F, Deshapriya S, Demir S. Guanidinate Yttrium Complexes Containing Bipyridyl and Bis(benzimidazolyl) Radicals. Inorg Chem 2024; 63:9659-9669. [PMID: 38569134 PMCID: PMC11134503 DOI: 10.1021/acs.inorgchem.4c00006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 02/26/2024] [Accepted: 03/06/2024] [Indexed: 04/05/2024]
Abstract
Ancillary ligand scaffolds that sufficiently stabilize a metal ion to allow its coordination to an open-shell ligand are scarce, yet their development is essential for next-generation spin-based materials with topical applications in quantum information science. To this end, a synthetic challenge must be met: devising molecules that enable the binding of a redox-active ligand through facile displacement and clean removal of a weakly coordinating anion. Here, we probe the accessibility of unprecedented radical-containing rare-earth guanidinate complexes by combining our recently discovered yttrium tetraphenylborate complex [{(Me3Si)2NC(NiPr)2}2Y][(μ-η6-Ph)(BPh3)] with the redox-active ligands 2,2'-bipyridine (bpy) and 2,2'-bis(benzimidazole) (Bbim), respectively, under reductive conditions. Our endeavor resulted in the first evidence of guanidinate complexes that contain radicals, namely, a mononuclear bipyridyl radical complex, {(Me3Si)2NC(NiPr)2}2Y(bpy•) (1), and a dinuclear bis(benzimidazolyl) radical-bridged complex, [K(crypt-222)][{(Me3Si)2NC(NiPr)2}2Y]2(μ-Bbim•) (2'). The latter was achieved by an in situ reduction of [{(Me3Si)2NC(NiPr)2}2Y]2(μ-Bbim) (2), which was isolated from a salt metathesis reaction. 1 and 2 were characterized by X-ray crystallography and IR and UV-vis spectroscopy. Variable-temperature electron paramagnetic resonance spectroscopy was applied to gain insight into the distribution of unpaired spin density on 1 and 2'. Density functional theory calculations were conducted on 1 and 2' to elucidate further their electronic structures. The redox activity of 1 and 2' was also probed by electrochemical methods.
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Affiliation(s)
| | | | - Selvan Demir
- Department of Chemistry, Michigan
State University (MSU), 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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7
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Nguyen JQ, Wedal JC, Ziller JW, Furche F, Evans WJ. Investigating Steric and Electronic Effects in the Synthesis of Square Planar 6d 1 Th(III) Complexes. Inorg Chem 2024; 63:6217-6230. [PMID: 38502000 DOI: 10.1021/acs.inorgchem.3c04462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The factors affecting the formation and crystal structures of unusual 6d1 Th(III) square planar aryloxide complexes, as exemplified by [Th(OArMe)4]1- (OArMe = OC6H2tBu2-2,6-Me-4), were explored by synthetic and reduction studies of a series of related Th(IV) tetrakis(aryloxide) complexes, Th(OArR)4 (OArR = OC6H2tBu2-2,6-R-4). Specifically, electronic, steric, and countercation effects were explored by varying the aryloxide ligand, the alkali metal reducing agent, and the alkali metal chelating agent. Salt metathesis reactions between ThBr4(DME)2 (DME = 1,2-dimethoxyethane) and 4 equiv of the appropriate potassium aryloxide salt were used to prepare a series of Th(IV) aryloxide complexes in high yields: Th(OArH)4 (OArH = OC6H3tBu2-2,6), Th(OArtBu)4 (OArtBu = OC6H2tBu3-2,4,6), Th(OArOMe)4 (OArOMe = OC6H2tBu2-2,6-OMe-4), and Th(OArPh)4 (OArPh = OC6H2tBu2-2,6-Ph-4). Th(OArH)4 can be reduced by KC8, Na, or Li in the absence or presence of 2.2.2-cryptand (crypt) or 18-crown-6 (crown) to form dark purple solutions that have EPR and UV-visible spectra similar to those of the square planar Th(III) complex, [Th(OArMe)4]1-. Hence, the para position of the aryloxide ligand does not have to be alkylated to obtain the Th(III) complexes. Furthermore, reduction of Th(OArOMe)4, Th(OArtBu)4, and Th(OArPh)4 with KC8 in THF generated purple solutions with EPR and UV-visible spectra that are similar to those of the previously reported Th(III) anion, [Th(OArMe)4]1-. Although many of these reduction reactions did not produce single crystals suitable for study by X-ray diffraction, reduction of Th(OArH)4, Th(OArtBu)4, and Th(OArOMe)4 with Li provided X-ray quality crystals whose structures had square planar coordination geometries. Reduction of Th(OArPh)4 with Li also gave a product with EPR and UV-visible spectra that matched those of [Th(OArMe)4]1-, but X-ray quality crystals of the reduction product were too unstable to provide data. Neither Th(Odipp)4(THF)2 (Odipp = OC6H3iPr2-2,6) nor Th(Odmp)4(THF)2 (Odmp = OC6H3Me2-2,6) could be reduced to Th(III) products under similar conditions. Reduction of U(OArH)3(THF) with KC8 in the presence of 2.2.2-cryptand (crypt) was examined for comparison and formed [K(crypt)][U(OArH)4], which has a tetrahedral arrangement of the aryloxide ligands. Moreover, no further reduction was observed when either [K(crypt)][U(OArH)4] or [K(crown)(THF)2][U(OArH)4] were treated with KC8 or Li.
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Affiliation(s)
- Joseph Q Nguyen
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Justin C Wedal
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - William J Evans
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
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Xue T, Ding YS, Zheng Z. A tetravalent praseodymium complex with field-induced slow magnetic relaxation. Dalton Trans 2024; 53:5779-5783. [PMID: 38482700 DOI: 10.1039/d4dt00052h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Herein the synthesis, structural characterization, and magnetic properties of a Pr(IV) complex [Pr(OSiPh3)4(L)] (1, L = 4,4'-dimethoxy-2,2'-bipyridine) are reported. The stability of the Pr(IV) complex significantly enhanced with the use of the bidentate ligand L. Slow magnetic relaxation was observed at low temperatures, indicating that the complex may be the first single-ion magnet with a tetravalent lanthanide ion being the magnetic center.
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Affiliation(s)
- Tianjiao Xue
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
- Key University Laboratory of Rare Earth Chemistry of Guangdong, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - You-Song Ding
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
- Key University Laboratory of Rare Earth Chemistry of Guangdong, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Zhiping Zheng
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
- Key University Laboratory of Rare Earth Chemistry of Guangdong, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
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9
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Wedal JC, Moore WNG, Lukens WW, Evans WJ. Perplexing EPR Signals from 5f 36d 1 U(II) Complexes. Inorg Chem 2024; 63:2945-2953. [PMID: 38279200 DOI: 10.1021/acs.inorgchem.3c03449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
Metal complexes with unpaired electrons in orbitals of different angular momentum quantum numbers (e.g., f and d orbitals) are unusual and opportunities to study the interactions among these electrons are rare. X-band electron paramagnetic resonance (EPR) data were collected at <10 and 77 K on 10 U(II) complexes with 5f36d1 electron configurations and on some analogous Ce(II), Pr(II), and Nd(II) complexes with 4fn5d1 electron configurations. The U(II) compounds unexpectedly display similar two-line axial signals with g|| = 2.04 and g⊥ = 2.00 at 77 K. In contrast, U(II) complexes with 5f4 configurations are EPR-silent. Unlike U(II), the congenic 4f35d1 Nd(II) complex is EPR-silent. The Ce(II) complex with a 4f15d1 configuration is also EPR-silent, but a signal is observed for the Pr(II) complex, which has a 4f25d1 configuration. Whether or not an EPR signal is expected for these complexes depends on the coupling between f and d electrons. Since the coupling in U(II) systems is expected to be sufficiently strong to preclude an EPR signal from compounds with a 5f36d1 configuration, the results are viewed as unexplained phenomena. However, they do show that 5f36d1 U(II) samples can be differentiated from 5f4 U(II) complexes by EPR spectroscopy.
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Affiliation(s)
- Justin C Wedal
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - William N G Moore
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Wayne W Lukens
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - William J Evans
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
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