1
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Otte KS, Niklas JE, Studvick CM, Montgomery CL, Bredar ARC, Popov IA, La Pierre HS. Proton-Coupled Electron Transfer at the Pu 5+/4+ Couple. J Am Chem Soc 2024. [PMID: 39051969 DOI: 10.1021/jacs.4c06319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
The synthesis and solution and solid-state characterization of [Pu4+(NPC)4], 1-Pu, (NPC = [NPtBu(pyrr)2]-; tBu = C(CH3)3; pyrr = pyrrolidinyl) and [Pu3+(NPC)4][K(2.2.2.-cryptand)], 2-Pu, is described. Cyclic voltammetry studies of 1-Pu reveal a quasi-reversible Pu4+/3+ couple, an irreversible Pu5+/4+ couple, and a third couple evincing a rapid proton-coupled electron transfer (PCET) reaction occurring after the electrochemical formation of Pu5+. The chemical identity of the product of the PCET reaction was confirmed by independent chemical synthesis to be [Pu4+(NPC)3(HNPC)][B(ArF5)4], 3-Pu, (B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate) via two mechanistically distinct transformations of 1-Pu: protonation and oxidation. The kinetics and thermodynamics of this PCET reaction are determined via electrochemical analysis, simulation, and density functional theory. The computational studies demonstrate a direct correlation between the changing nature of 5f and 6d orbital participation in metal-ligand bonding and the electron density on the Nim atom with the thermodynamics of the PCET reaction from Np to Pu, and an indirect correlation with the roughly 5-orders of magnitude faster Pu PCET compared to Np for the An5+ species.
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Affiliation(s)
- Kaitlyn S Otte
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Julie E Niklas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Chad M Studvick
- Department of Chemistry, University of Akron, Akron, Ohio 44325-3601, United States
| | - Charlotte L Montgomery
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexandria R C Bredar
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Ivan A Popov
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Henry S La Pierre
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- Nuclear and Radiological Engineering and Medical Physics Program, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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2
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Mikeska ER, Wilson RE, Sen A, Autschbach J, Blakemore JD. Preparation of Neptunyl and Plutonyl Acetates To Access Nonaqueous Transuranium Coordination Chemistry. J Am Chem Soc 2024. [PMID: 39047184 DOI: 10.1021/jacs.4c04613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Uranyl diacetate dihydrate is a useful reagent for the preparation of uranyl (UO22+) coordination complexes, as it is a well-defined stoichiometric compound featuring moderately basic acetates that can facilitate protonolysis reactivity, unlike other anions commonly used in synthetic actinide chemistry such as halides or nitrate. Despite these attractive features, analogous neptunium (Np) and plutonium (Pu) compounds are unknown to date. Here, a modular synthetic route is reported for accessing stoichiometric neptunyl(VI) and plutonyl(VI) diacetate compounds that can serve as starting materials for transuranic coordination chemistry. The new NpO22+ and PuO22+ complexes, as well as a corresponding molecular UO22+ complex, are isomorphous in the solid state, and in solution show similar solubility properties that facilitate their use in synthesis. In both solid and solution state, the +VI oxidation state (O.S.) is maintained, as demonstrated by vibrational and optical spectroscopy, confirming that acetate anions stabilize the oxidizing, high-valent +VI states of Np and Pu as they do for the more stable U(VI). All three acetate salts readily react with a model diprotic ligand, affording incorporation of U(VI), Np(VI), and Pu(VI) cores into molecular coordination compounds that occurs concomitantly with elimination of acetic acid; the new complexes are high-valent, yet overall charge neutral, facilitating entry into nonaqueous chemistry by rational synthesis. Computational studies reveal that the dianionic ligand framework assists in stabilizing the +VI O.S. via donation to the 5f shells of the actinides, highlighting the potential usefulness of protonolysis reactivity toward preparation of stabilized high-valent transuranic species.
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Affiliation(s)
- Emily R Mikeska
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Richard E Wilson
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Asmita Sen
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - James D Blakemore
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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3
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Kulasekara DN, Bailey MD, Ward CL, Allen MJ. Comparison of the structural, electrochemical, and spectroscopic properties of two cryptates of trivalent uranium. Dalton Trans 2024; 53:8657-8661. [PMID: 38695748 PMCID: PMC11106807 DOI: 10.1039/d4dt00521j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 04/27/2024] [Indexed: 05/22/2024]
Abstract
We describe a study of the influence of cryptand denticity on the structural, electronic, and electrochemical properties of UIII-containing cryptates. Two cryptands (2.2.2 and 2.2.1) are reported. The cryptand with the smaller denticity leads to negative electrochemical potentials and shorter bond lengths that are consistent with a better fit for UIII than the larger cryptand. These studies provide insight into the rational design of cryptand-based ligands for trivalent uranium.
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Affiliation(s)
- D Nuwangi Kulasekara
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
| | - Matthew D Bailey
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
| | - Cassandra L Ward
- Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA
| | - Matthew J Allen
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
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4
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Murillo J, Seed JA, Wooles AJ, Oakley MS, Goodwin CAP, Gregson M, Dan D, Chilton NF, Gaunt AJ, Kozimor SA, Liddle ST, Scott BL. Carbene Complexes of Plutonium: Structure, Bonding, and Divergent Reactivity to Lanthanide Analogs. J Am Chem Soc 2024; 146:4098-4111. [PMID: 38301208 PMCID: PMC10870714 DOI: 10.1021/jacs.3c12719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/21/2023] [Accepted: 01/08/2024] [Indexed: 02/03/2024]
Abstract
Organoplutonium chemistry was established in 1965, yet structurally authenticated plutonium-carbon bonds remain rare being limited to π-bonded carbocycle and σ-bonded isonitrile and hydrocarbyl derivatives. Thus, plutonium-carbenes, including alkylidenes and N-heterocyclic carbenes (NHCs), are unknown. Here, we report the preparation and characterization of the diphosphoniomethanide-plutonium complex [Pu(BIPMTMSH)(I)(μ-I)]2 (1Pu, BIPMTMSH = (Me3SiNPPh2)2CH) and the diphosphonioalkylidene-plutonium complexes [Pu(BIPMTMS)(I)(DME)] (2Pu, BIPMTMS = (Me3SiNPPh2)2C) and [Pu(BIPMTMS)(I)(IMe4)2] (3Pu, IMe4 = C(NMeCMe)2), thus disclosing non-actinyl transneptunium multiple bonds and transneptunium NHC complexes. These Pu-C double and dative bonds, along with cerium, praseodymium, samarium, uranium, and neptunium congeners, enable lanthanide-actinide and actinide-actinide comparisons between metals with similar ionic radii and isoelectronic 4f5 vs 5f5 electron-counts within conserved ligand fields over 12 complexes. Quantum chemical calculations reveal that the orbital-energy and spatial-overlap terms increase from uranium to neptunium; however, on moving to plutonium the orbital-energy matching improves but the spatial overlap decreases. The bonding picture that emerges is more complex than the traditional picture of the bonding of lanthanides being ionic and early actinides being more covalent but becoming more ionic left to right. Multiconfigurational calculations on 2M and 3M (M = Pu, Sm) account for the considerably more complex UV/vis/NIR spectra for 5f5 2Pu and 3Pu compared to 4f5 2Sm and 3Sm. Supporting the presence of Pu═C double bonds in 2Pu and 3Pu, 2Pu exhibits metallo-Wittig bond metathesis involving the highest atomic number element to date, reacting with benzaldehyde to produce the alkene PhC(H)═C(PPh2NSiMe3)2 (4) and "PuOI". In contrast, 2Ce and 2Pr do not react with benzaldehyde to produce 4.
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Affiliation(s)
- Jesse Murillo
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - John A. Seed
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Ashley J. Wooles
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Meagan S. Oakley
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Conrad A. P. Goodwin
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Matthew Gregson
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - David Dan
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Nicholas F. Chilton
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
- Research
School of Chemistry, The Australian National
University, Sullivans
Creek Road, Canberra, ACT 2601, Australia
| | - Andrew J. Gaunt
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Stosh A. Kozimor
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Stephen T. Liddle
- Department
of Chemistry and Centre for Radiochemistry Research, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Brian L. Scott
- Materials
Physics & Applications Division, Los
Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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5
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Degtyareva SS, Bardonov DA, Afanaseva AV, Puntus LN, Lyssenko KA, Birin KP, Minyaev ME, Burykina JV, Taydakov IV, Varaksina EA, Nifant'ev IE, Roitershtein DM. Tridentate Nitrogen Ligand as a Tool for the Construction of Well-Defined Rare Earth Trichloride Complexes. Inorg Chem 2024; 63:1867-1878. [PMID: 38237143 DOI: 10.1021/acs.inorgchem.3c03492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
LnCl3(THF)3 (Ln = Y, La ÷ Nd, Sm ÷ Lu) readily react with the tridentate 1,3,5-trimethyl-1,3,5-triazacyclohexane (Me3tach) ligand to form mono- or binuclear lanthanide trichloride complexes, depending on the stoichiometry of the reaction and the ionic radius of the metal: mononuclear pseudosandwich [LnCl3(Me3tach)2], (Ln = Y, La ÷ Ho) or binuclear complexes [Ln2Cl6(Me3tach)3], or [LnCl3(Me3tach)(THF)]2 (Ln = Sm, Tb). Detailed analysis of the NMR data of [LnCl3(Me3tach)2] complexes with paramagnetic lanthanide ions showed that their structures remained unchanged in the toluene solution. A series of isomorphous complexes [LnCl3(Me3tach)(Py)2] (Ln = La, Sm, Tb, Er, Lu; Py = pyridine) have been obtained by the recrystallization of either mononuclear or binuclear complexes from pyridine. Complexes of terbium and europium ions with the Me3tach ligand exhibit relatively high quantum yields of metal-centered luminescence (0.39 and 0.32, respectively).
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Affiliation(s)
- Svetlana S Degtyareva
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- National Research University Higher School of Economics (HSE University), 101000 Moscow, Russian Federation
| | - Daniil A Bardonov
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- National Research University Higher School of Economics (HSE University), 101000 Moscow, Russian Federation
| | - Anna V Afanaseva
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- National Research University Higher School of Economics (HSE University), 101000 Moscow, Russian Federation
| | - Lada N Puntus
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- V.A. Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Fryazino, 141190 Moscow, Russian Federation
| | - Konstantin A Lyssenko
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russian Federation
| | - Kirill P Birin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russian Federation
| | - Mikhail E Minyaev
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation
| | - Julia V Burykina
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation
| | - Ilya V Taydakov
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russian Federation
| | - Evgenia A Varaksina
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russian Federation
| | - Ilya E Nifant'ev
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russian Federation
| | - Dmitrii M Roitershtein
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation
- National Research University Higher School of Economics (HSE University), 101000 Moscow, Russian Federation
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation
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6
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Otte KS, Niklas JE, Studvick CM, Boggiano AC, Bacsa J, Popov IA, La Pierre HS. Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes. Angew Chem Int Ed Engl 2023; 62:e202306580. [PMID: 37327070 DOI: 10.1002/anie.202306580] [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: 05/10/2023] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 06/18/2023]
Abstract
The study of the redox chemistry of mid-actinides (U-Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=Pt Bu(pyrr)2 ]- ; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U5+/4+ , U6+/5+ , and to an unprecedented, well-behaved Np5+/4+ redox couple. The differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.
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Affiliation(s)
- Kaitlyn S Otte
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - Julie E Niklas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - Chad M Studvick
- Department of Chemistry, The University of Akron, Akron, OH, 44325-3601, USA
| | - Andrew C Boggiano
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - John Bacsa
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - Ivan A Popov
- Department of Chemistry, The University of Akron, Akron, OH, 44325-3601, USA
| | - Henry S La Pierre
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
- Nuclear and Radiological Engineering Program, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
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7
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Peluzo BMTC, Makoś MZ, Moura RT, Freindorf M, Kraka E. Linear versus Bent Uranium(II) Metallocenes─A Local Vibrational Mode Study. Inorg Chem 2023. [PMID: 37478353 DOI: 10.1021/acs.inorgchem.3c01761] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Uranium metallocenes have recently attracted attention driven by their use as catalysts in organometallic synthesis. In addition to bent U(IV) and U(III), an U(II) metallocene [(η5-C5i Pr5)2U] was synthesized with an unusual linear Cp-U-Cp angle. In this work, we investigated 22 U(II) metallocenes, (i) assessing the intrinsic strength of the U-ring interactions in these complexes with a novel bond strength measure based on our local vibrational mode analysis and (ii) systematically exploring what makes these U(II) metallocenes bent. We included relativistic effects through the NESCau Hamiltonian and complemented the local mode analysis with natural bonding orbital (NBO) and quantum theory of atoms in molecules (QTAIM) data. Our study led to the following results: (i) reduction of bulky U-ring ligand substituents does not lead to bent complexes for alkyl substituents (iPr and iBu) in contrast to SiMe3 ring substituents, which are all bent. (ii) The most bent complexes are [(η5-C5H4SiMe3)2U] (130°) and [η5-P5H5)2U] (143°). (iii) Linear complexes showed one hybridized NBO with s/d character, while bent structures were characterized by s/d/f mixing. (iv) We did not observe a correlation between the strength of the U-ring interaction and the amount of the ring-U-ring bend; the strongest interaction was found for [η5-Cp)2U] and the weakest for [η5-P5H5)2U]. In conclusion, our results provide a foundation for the design of U(II) metallocenes with specific physicochemical properties and increased reactivity.
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Affiliation(s)
- Bárbara M T C Peluzo
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Małgorzata Z Makoś
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
- Chemical Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37830, United States
| | - Renaldo T Moura
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
- Department of Chemistry and Physics, Center of Agrarian Sciences, Federal University of Paraíba, Areia 58397-000, Paraíba, Brazil
| | - Marek Freindorf
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Elfi Kraka
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
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8
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Wedal JC, Ziller JW, Evans WJ. Trimethyltriazacyclohexane coordination chemistry of simple rare-earth metal salts. Dalton Trans 2023; 52:4787-4795. [PMID: 36938859 DOI: 10.1039/d3dt00242j] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
Reactions of 1,3,5-trimethyl-triazacyclohexane (Me3tach) with common rare-earth metal iodide, chloride, and triflate salts were examined to determine the capacity of this inexpensive chelate to provide alternative precursors for THF-free reactions. The reaction of LaI3(THF)4 and CeI3(THF)4 with 1,3,5-trimethyl-triazacyclohexane in THF generated toluene soluble (Me3tach)2LnI3, 1-Ln, in which the Ln center has a tri-capped trigonal prismatic geometry with two eclipsed Me3tach rings. Reaction with NdI3(THF)3.5 forms the analogous 1-Nd, but a different structure with one outer sphere iodide, [(Me3tach)2NdI2][I], 2-Nd, is also accessible and has a structure reminiscent of bent metallocenes. The reaction of LaCl3 and Me3tach forms the less soluble (Me3tach)2LaCl3, which has a structure analogous to 1-Ln with eclipsed Me3tach rings. The mono-ring yttrium complex, (Me3tach)YCl3(THF)2, could be isolated from the reaction of YCl3 with Me3tach. Reactions of La(OTf)3 with Me3tach were sensitive to the presence of residual proton sources as exemplified by the isolation of {[(Me3tach)La(μ-OH)(μ-OTf)]2(μ-OTf)2}2, 5-La, and [HMe3tach][(Me3tach)2La-(OTf)4], 6-La. SmI2 reacts with Me3tach to produce the Sm(II) complex, (Me3tach)2SmI2(THF), 7-Sm, but 2-Sm can also form in this reaction. Complexes of the larger 1,4,7-trimethyltriazacyclononane (Me3tacn) ligand, namely (Me3tacn)LaI3(THF), (Me3tacn)YCl3, and (Me3tacn)SmI2(THF) were synthesized for comparison. Several examples of the protonated ligands with simple counteranions, [HMe3tach][X] (X = Cl, Br, I) and [HMe3tacn][OTf], were identified in the course of these studies.
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Affiliation(s)
- Justin C Wedal
- Department of Chemistry, University of California Irvine, Irvine, CA 92617, USA.
| | - Joseph W Ziller
- Department of Chemistry, University of California Irvine, Irvine, CA 92617, USA.
| | - William J Evans
- Department of Chemistry, University of California Irvine, Irvine, CA 92617, USA.
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