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Ismael F, Fleming CL, Christopher TD, Söhnel T, Zhou Y, Krenske EH, Gahan LR, Blackman AG. Co(III) complexes of the pentadentate NHC ligand PY4Im: carbene-induced trans influences and the non-disappearing 13C NMR peak. Dalton Trans 2024; 53:12688-12697. [PMID: 39015102 DOI: 10.1039/d4dt01579g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Co(III) complexes of the N-heterocyclic carbene ligand PY4Im (PY4Im = (1,3-bis(bis(2-pyridyl)methyl)imidazol-2-ylidene)) having the general formula [(PY4Im)Co(X)](ClO4)n (X = NCMe; n = 3: OH-, N3-, NCS-, ONO-, F-; n = 2: O2CO2-, n = 1; (N3-)3, n = 0) were prepared and structurally characterised. X-ray structural data are consistent with the presence of a trans influence due to the coordinated carbene carbon, and this is also supported by computational results. 13C NMR spectra of the complexes did not display peaks corresponding to the carbene carbon, except in the case of the [(PY4Im)Co(O2CO)]+ cation, where a peak at δ = 170.21 ppm was observed. However, HMBC spectra allowed indirect determination of the chemical shifts of the carbene carbon in the remaining complexes, owing to the geometry of the PY4Im ligand. Calculated 13C chemical shifts for the complexes showed very good agreement with the experimental values for all but the carbene carbon atoms in all cases.
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Affiliation(s)
- Fouad Ismael
- Department of Chemistry, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
| | - Cassandra L Fleming
- Department of Chemistry, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
- The University of Sydney, Chemistry Building, Eastern Ave, Camperdown, NSW 2050, Australia
| | - Timothy D Christopher
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Tilo Söhnel
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - Yuchen Zhou
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Elizabeth H Krenske
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Allan G Blackman
- Department of Chemistry, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
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2
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Neururer F, Huter K, Seidl M, Hohloch S. Reactivity and Structure of a Bis-phenolate Niobium NHC Complex. ACS ORGANIC & INORGANIC AU 2022; 3:59-71. [PMID: 36748079 PMCID: PMC9896488 DOI: 10.1021/acsorginorgau.2c00028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022]
Abstract
We report the facile synthesis of a rare niobium(V) imido NHC complex with a dianionic OCO-pincer benzimidazolylidene ligand (L 1 ) with the general formula [NbL 1 (N t Bu)PyCl] 1-Py. We achieved this by in situ deprotonation of the corresponding azolium salt [H 3 L 1 ][Cl] and subsequent reaction with [Nb(N t Bu)Py 2 Cl 3 ]. The pyridine ligand in 1-Py can be removed by the addition of B(C6F5)3 as a strong Lewis acid leading to the formation of the pyridine-free complex 1. In contrast to similar vanadium(V) complexes, complex 1-Py was found to be a good precursor for various salt metathesis reactions, yielding a series of chalcogenido and pnictogenido complexes with the general formula [ NbL 1 (N t Bu)Py(EMes)] (E = O (2), S (3), NH (4), and PH (5)). Furthermore, complex 1-Py can be converted to alkyl complex (6) with 1 equiv of neosilyl lithium as a transmetallation agent. Addition of a second equivalent yields a new trianionic supporting ligand on the niobium center (7) in which the benzimidazolylidene ligand is alkylated at the former carbene carbon atom. The latter is an interesting chemically "noninnocent" feature of the benzimidazolylidene ligand potentially useful in catalysis and atom transfer reactions. Addition of mesityl lithium to 1-Py gives the pyridine-free aryl complex 8, which is stable toward "overarylation" by an additional equivalent of mesityl lithium. Electrochemical investigation revealed that complexes 1-Py and 1 are inert toward reduction in dichloromethane but show two irreversible reduction processes in tetrahydrofuran as a solvent. However, using standard reduction agents, e.g., KC8, K-mirror, and Na/Napht, no reduced products could be isolated. All complexes have been thoroughly studied by various techniques, including 1H-, 13C{1H}-, and 1H-15N HMBC NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis.
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Horrer G, Krummenacher I, Mann S, Braunschweig H, Radius U. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of vanadium(III) and vanadium(V). Dalton Trans 2022; 51:11054-11071. [PMID: 35796195 DOI: 10.1039/d2dt01250b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
[VCl3(THF)3] offers a convenient entrance point into the chemistry of carbene stabilized V(III) complexes. Herein we report the paramagnetic mono- and biscarbene complexes [VCl3(cAACMe)] 1, [VCl3(cAACMe)(THF)] 1(thf), [VCl3(IMes)] 2, [{VCl2(IiPrMe)(μ-Cl)}2] 3, [VCl3(IDipp)] 4, [VCl3(SIDipp)] 5, [VCl3(SIDipp)(THF)] 5(thf), [VCl3(ItBu)] 6, [VCl3(cAACMe)2] 7 and [VCl3(IiPrMe)2] 8. Reaction of 1 with MesMgCl, MesLi and LiNPh2 afforded the complexes [VCl2(Mes)(cAACMe)] 9, [cAACMeH]+[VCl2Mes2]-10 and [VCl2(NPh2)(cAACMe)] 11. The V(V) complexes [V(O)Cl3(IDipp)] 12 and [V(O)Cl3(SIDipp)] 13 were selectively prepared from oxygen oxidation of 4 and 5. [V(O)Cl3(IDipp)] 12 and [V(O)Cl3(IMes)] react with isocyanates to yield the NHC-ligated imido complexes [V(N-p-CH3C6H4)Cl3(IDipp)] 14, [V(N-p-FC6H4)Cl3(IDipp)] 15, [V(N-p-CH3C6H4)Cl3(SIDipp)] 16, [V(N-p-FC6H4)Cl3(SIDipp)] 17, [V(N-p-CH3C6H4)Cl3(IMes)] 18 and [V(N-p-FC6H4)Cl3(IMes)] 19.
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Affiliation(s)
- Günther Horrer
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Ivo Krummenacher
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sophie Mann
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Udo Radius
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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Weberg AB, Chaudhuri S, Cheisson T, Uruburo C, Lapsheva E, Pandey P, Gau MR, Carroll PJ, Schatz GC, Schelter EJ. Tantalum, easy as Pi: understanding differences in metal–imido bonding towards improving Ta/Nb separations. Chem Sci 2022; 13:6796-6805. [PMID: 35774165 PMCID: PMC9200122 DOI: 10.1039/d2sc01926d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 05/10/2022] [Indexed: 12/04/2022] Open
Abstract
The separation and purification of niobium and tantalum, which co-occur in natural sources, is difficult due to their similar physical and chemical properties. The current industrial method for separating Ta/Nb mixtures uses an energy-intensive process with caustic and toxic conditions. It is of interest to develop alternative, fundamental methodologies for the purification of these technologically important metals that improve upon their environmental impact. Herein, we introduce new Ta/Nb imido compounds: M(tBuN)(TriNOx) (1-M) bound by the TriNOx3− ligand and demonstrate a fundamental, proof-of-concept Ta/Nb separation based on differences in the imido reactivities. Despite the nearly identical structures of 1-M, density functional theory (DFT)-computed electronic structures of 1-M indicate enhanced basic character of the imido group in 1-Ta as compared to 1-Nb. Accordingly, the rate of CO2 insertion into the M
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Nimido bond of 1-Ta to form a carbamate complex (2-Ta) was selective compared to the analogous, unobserved reaction with 1-Nb. Differences in solubility between the imido and carbamate complexes allowed for separation of the carbamate complex, and led to an efficient Ta/Nb separation (STa/Nb = 404 ± 150) dependent on the kinetic differences in nucleophilicities between the imido moieties in 1-Ta and 1-Nb. A selective separation of the critical metals tantalum and niobium was accomplished from π-bonding-based reactivity differences of imido complexes. New insights into Ta/Nb separations were gained through detailed kinetic and computational studies.![]()
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Affiliation(s)
- Alexander B. Weberg
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Subhajyoti Chaudhuri
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Thibault Cheisson
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Christian Uruburo
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Ekaterina Lapsheva
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Pragati Pandey
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Michael R. Gau
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - Patrick J. Carroll
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
| | - George C. Schatz
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Eric J. Schelter
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA
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5
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Neururer F, Liu S, Leitner D, Baltrun M, Fisher KR, Kopacka H, Wurst K, Daumann LJ, Munz D, Hohloch S. Mesoionic Carbenes in Low- to High-Valent Vanadium Chemistry. Inorg Chem 2021; 60:15421-15434. [PMID: 34590834 PMCID: PMC8527456 DOI: 10.1021/acs.inorgchem.1c02087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Indexed: 12/12/2022]
Abstract
We report the synthesis of vanadium(V) oxo complex 1 with a pincer-type dianionic mesoionic carbene (MIC) ligand L1 and the general formula [VOCl(L1)]. A comparison of the structural (SC-XRD), electronic (UV-vis), and electrochemical (cyclic voltammetry) properties of 1 with the benzimidazolinylidene congener 2 (general formula [VOCl(L2)]) shows that the MIC is a stronger donor also for early transition metals with low d-electron population. Since electrochemical studies revealed both complexes to be reversibly reduced, the stronger donor character of MICs was not only demonstrated for the vanadium(V) but also for the vanadium(IV) oxidation state by isolating the reduced vanadium(IV) complexes [Co(Cp*)2][1] and [Co(Cp*)2][2] ([Co(Cp*)2] = decamethylcobaltocenium). The electronic structures of the compounds were investigated by computational methods. Complex 1 was found to be a moderate precursor for salt metathesis reactions, showing selective reactivity toward phenolates or secondary amides, but not toward primary amides and phosphides, thiophenols, or aryls/alkyls donors. Deoxygenation with electron-rich phosphines failed to give the desired vanadium(III) complex. However, treatment of the deprotonated ligand precursor with vanadium(III) trichloride resulted in the clean formation of the corresponding MIC vanadium(III) complex 6, which undergoes a clean two-electron oxidation with organic azides yielding the corresponding imido complexes. The reaction with TMS-N3 did not afford a nitrido complex, but instead the imido complex 10. This study reveals that, contrary to popular belief, MICs are capable of supporting early transition-metal complexes in a variety of oxidation states, thus making them promising candidates for the activation of small molecules and redox catalysis.
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Affiliation(s)
- Florian
R. Neururer
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Shenyu Liu
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Daniel Leitner
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Marc Baltrun
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Katherine R. Fisher
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Holger Kopacka
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Klaus Wurst
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Lena J. Daumann
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Dominik Munz
- Fakultät
NT, Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Stephan Hohloch
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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