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Hanft A, Radacki K, Lichtenberg C. Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties. Chemistry 2021; 27:6230-6239. [PMID: 33326650 PMCID: PMC8048980 DOI: 10.1002/chem.202005186] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Indexed: 01/03/2023]
Abstract
The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)3] and [Bi(ATI)2Ln][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored.
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Hanft A, Radacki K, Lichtenberg C. Cover Feature: Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties (Chem. Eur. J. 20/2021). Chemistry 2021. [DOI: 10.1002/chem.202100363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Brunecker C, Arrowsmith M, Müssig JH, Böhnke J, Stoy A, Heß M, Hofmann A, Lenczyk C, Lichtenberg C, Ramler J, Rempel A, Braunschweig H. Synthesis and characterisation of boranediyl- and diboranediyl-bridged diplatinum A-frame complexes. Dalton Trans 2021; 50:3506-3515. [PMID: 33442715 DOI: 10.1039/d0dt03855e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of boranediyl-bridged diplatinum A-frame complexes, [Pt2X2(μ-BY)(μ-dmpm)2] (X = Cl, Br, I; Y = aryl, alkyl, amino, halo; dmpm = bis(dimethylphosphino)methane), were synthesised by the twofold oxidative addition of BX2Y to [Pt2(nbe)2(μ-dmpm)2] (nbe = norbornene) or to the paddlewheel complex [Pt2(μ-dmpm)3]. Similarly, the addition of B2X2(NMe2)2 (X = Cl, Br) to [Pt2(nbe)2(μ-dmpm)2] provided access to the diborane-1,2-diyl-bridged A-frame complexes [Pt2X2(μ-1,2-B2(NMe2)2)(μ-dmpm)2]. X-ray crystallographic studies of these (BY)n-bridged complexes show structural trends depending on the steric demands of Y and the nature of X. Analysis of higher-order 31P NMR satellites provided information on JP-Pt and JPt-Pt coupling constants, the latter correlating with the PtPt distance. All (di)boranediyl complexes also proved unstable towards (successive) loss of the bridging "BY" unit(s), resulting in the formation of [Pt2X2(μ-dmpm)2].
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Oberdorf K, Hanft A, Ramler J, Krummenacher I, Bickelhaupt FM, Poater J, Lichtenberg C. Bismutamide als einfache Vermittler hochselektiver Pn−Pn‐Radikal‐Kupplungsreaktionen (Pn=N, P, As). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Oberdorf K, Hanft A, Ramler J, Krummenacher I, Bickelhaupt FM, Poater J, Lichtenberg C. Bismuth Amides Mediate Facile and Highly Selective Pn-Pn Radical-Coupling Reactions (Pn=N, P, As). Angew Chem Int Ed Engl 2021; 60:6441-6445. [PMID: 33315293 PMCID: PMC7986226 DOI: 10.1002/anie.202015514] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Indexed: 12/14/2022]
Abstract
The controlled release of well-defined radical species under mild conditions for subsequent use in selective reactions is an important and challenging task in synthetic chemistry. We show here that simple bismuth amide species [Bi(NAr2 )3 ] readily release aminyl radicals [NAr2 ]. at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar2 N-NAr2 , as a result of highly selective N-N coupling. The exploitation of facile homolytic Bi-Pn bond cleavage for Pn-Pn bond formation was extended to higher homologues of the pnictogens (Pn=N-As): homoleptic bismuth amides mediate the highly selective dehydrocoupling of HPnR2 to give R2 Pn-PnR2 . Analyses by NMR and EPR spectroscopy, single-crystal X-ray diffraction, and DFT calculations reveal low Bi-N homolytic bond-dissociation energies, suggest radical coupling in the coordination sphere of bismuth, and reveal electronic and steric parameters as effective tools to control these reactions.
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Ramler J, Wüst L, Rempel A, Wolz L, Lichtenberg C. Bismuth Atoms in Hydrocarbon Ligands: Bismepines as Rigid, Ditopic Arene Donors in Coordination Chemistry. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lichtenberg C. Molecular bismuth(iii) monocations: structure, bonding, reactivity, and catalysis. Chem Commun (Camb) 2021; 57:4483-4495. [DOI: 10.1039/d1cc01284c] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Structurally defined, molecular bismuth(iii) cations show remarkable properties in coordination chemistry, Lewis acidity, and redox chemistry, allowing for unique applications in synthetic chemistry.
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Hanft A, Jürgensen M, Wolz L, Radacki K, Lichtenberg C. Salicylaldimines: Formation via Ring Contraction and Synthesis of Mono- and Heterobimetallic Alkali Metal Heterocubanes. Inorg Chem 2020; 59:17678-17688. [PMID: 33226783 DOI: 10.1021/acs.inorgchem.0c02920] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The formation of salicylaldimine derivatives via ring contraction as byproducts in 2-aminotropone syntheses has been investigated. Salicylaldiminate (SAI) complexes of the alkali metals Li-K have been synthesized and transformed into heterobimetallic complexes. Important findings include an unusual double heterocubane structure of the homometallic sodium SAI, an unprecedented ligand-induced E/Z isomerization of the aldimine functional group in the homometallic potassium SAI, and the first example of a structurally authenticated mixed-metal SAI based on s-block central atoms. Rapid equilibria have been shown to play a crucial role in the solution phase chemistry of mixed-metal SAIs. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, VT- and DOSY NMR spectroscopy, high-resolution mass spectrometry, single-crystal X-ray diffraction analysis, and DFT calculations.
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Ramler J, Krummenacher I, Lichtenberg C. Well-Defined, Molecular Bismuth Compounds: Catalysts in Photochemically Induced Radical Dehydrocoupling Reactions. Chemistry 2020; 26:14551-14555. [PMID: 32573876 PMCID: PMC7821184 DOI: 10.1002/chem.202002219] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/08/2020] [Indexed: 01/12/2023]
Abstract
A series of diorgano(bismuth)chalcogenides, [Bi(di-aryl)EPh], has been synthesised and fully characterised (E=S, Se, Te). These molecular bismuth complexes have been exploited in homogeneous photochemically-induced radical catalysis, using the coupling of silanes with TEMPO as a model reaction (TEMPO=(tetramethyl-piperidin-1-yl)-oxyl). Their catalytic properties are complementary or superior to those of known catalysts for these coupling reactions. Catalytically competent intermediates of the reaction have been identified. Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single-crystal X-ray diffraction analysis, and (TD)-DFT calculations.
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Ramler J, Lichtenberg C. Cover Feature: Molecular Bismuth Cations: Assessment of Soft Lewis Acidity (Chem. Eur. J. 45/2020). Chemistry 2020. [DOI: 10.1002/chem.202003165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ramler J, Lichtenberg C. Molecular Bismuth Cations: Assessment of Soft Lewis Acidity. Chemistry 2020; 26:10250-10258. [PMID: 32428329 PMCID: PMC7818483 DOI: 10.1002/chem.202001674] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/10/2020] [Indexed: 02/06/2023]
Abstract
Three-coordinate cationic bismuth compounds [Bi(diaryl)(EPMe3 )][SbF6 ] have been isolated and fully characterized (diaryl=[(C6 H4 )2 C2 H2 ]2- , E=S, Se). They represent rare examples of molecular complexes with Bi⋅⋅⋅EPR3 interactions (R=monoanionic substituent). The 31 P NMR chemical shift of EPMe3 has been found to be sensitive to the formation of LA⋅⋅⋅EPMe3 Lewis acid/base interactions (LA=Lewis acid). This corresponds to a modification of the Gutmann-Beckett method and reveals information about the hardness/softness of the Lewis acid under investigation. A series of organobismuth compounds, bismuth halides, and cationic bismuth species have been investigated with this approach and compared to traditional group 13 and cationic group 14 Lewis acids. Especially cationic bismuth species have been shown to be potent soft Lewis acids that may prefer Lewis pair formation with a soft (S/Se-based) rather than a hard (O/N-based) donor. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, single-crystal X-ray diffraction analysis, and DFT calculations.
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Mukhopadhyay DP, Schleier D, Wirsing S, Ramler J, Kaiser D, Reusch E, Hemberger P, Preitschopf T, Krummenacher I, Engels B, Fischer I, Lichtenberg C. Methylbismuth: an organometallic bismuthinidene biradical. Chem Sci 2020; 11:7562-7568. [PMID: 32874526 PMCID: PMC7450715 DOI: 10.1039/d0sc02410d] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/02/2020] [Indexed: 12/04/2022] Open
Abstract
We report the generation, spectroscopic characterization, and computational analysis of the first free (non-stabilized) organometallic bismuthinidene, BiMe. The title compound was generated in situ from BiMe3 by controlled homolytic Bi-C bond cleavage in the gas phase. Its electronic structure was characterized by a combination of photoion mass-selected threshold photoelectron spectroscopy and DFT as well as multi-reference computations. A triplet ground state was identified and an ionization energy (IE) of 7.88 eV was experimentally determined. Methyl abstraction from BiMe3 to give [BiMe2]• is a key step in the generation of BiMe. We reaveal a bond dissociation energy of 210 ± 7 kJ mol-1, which is substantially higher than the previously accepted value. Nevertheless, the homolytic cleavage of Me-BiMe2 bonds could be achieved at moderate temperatures (60-120 °C) in the condensed phase, suggesting that [BiMe2]• and BiMe are accessible as reactive intermediates under these conditions.
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Lichtenberg C. Main-Group Metal Complexes in Selective Bond Formations Through Radical Pathways. Chemistry 2020; 26:9674-9687. [PMID: 32048770 PMCID: PMC7496981 DOI: 10.1002/chem.202000194] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/10/2020] [Indexed: 12/21/2022]
Abstract
Recent years have witnessed remarkable advances in radical reactions involving main-group metal complexes. This includes the isolation and detailed characterization of main-group metal radical compounds, but also the generation of highly reactive persistent or transient radical species. A rich arsenal of methods has been established that allows control over and exploitation of their unusual reactivity patterns. Thus, main-group metal compounds have entered the field of selective bond formations in controlled radical reactions. Transformations that used to be the domain of late transition-metal compounds have been realized, and unusual selectivities, high activities, as well as remarkable functional-group tolerances have been reported. Recent findings demonstrate the potential of main-group metal compounds to become standard tools of synthetic chemistry, catalysis, and materials science, when operating through radical pathways.
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Lichtenberg C. Frontispiece: Main‐Group Metal Complexes in Selective Bond Formations Through Radical Pathways. Chemistry 2020. [DOI: 10.1002/chem.202084461] [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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Ramler J, Radacki K, Abbenseth J, Lichtenberg C. Combined experimental and theoretical studies towards mutual osmium-bismuth donor/acceptor bonding. Dalton Trans 2020; 49:9024-9034. [PMID: 32567644 DOI: 10.1039/d0dt01663b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Osmium(ii) PNP pincer complexes bearing a hemilabile pyridyl-pyrazolide (PyrPz) ligand have been synthesised, and their reactivity towards Lewis acidic bismuth compounds has been examined. Reactions with BiCl3 resulted in chlorine-atom-transfer to give an osmium(iii) species. Reactions with cationic bismuth species led to adduct formation through N → Bi bond formation via the PyrPz ligand. Theoretical analyses revealed that steric interactions hamper Os → Bi bond formation and indicate that such interactions are possible upon reducing the steric profile around the osmium atom. Analytical techniques include NMR, IR, and EPR spectroscopy, cyclic voltammetry, elemental analysis and DFT calculations.
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Hanft A, Lichtenberg C. Dimerization of 2-[(2-((2-aminophenyl)thio)phenyl)amino]-cyclohepta-2,4,6-trien-1-one through hydrogen bonding, C 19H 16N 2OS. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2020-0124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C19H16N2OS, triclinic, P1̄ (no. 2), a = 8.1510(3) Å, b = 8.8021(3) Å, c = 11.3953(5) Å, α = 72.546(2)°, β = 84.568(2)°, γ = 80.760(2)°, V = 768.86(5) Å3, Z = 2, R
gt(F) = 0.0491, wR
ref(F
2) = 0.1494, T = 100 K.
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Ramler J, Hofmann K, Lichtenberg C. Neutral and Cationic Bismuth Compounds: Structure, Heteroaromaticity, and Lewis Acidity of Bismepines. Inorg Chem 2019; 59:3367-3376. [DOI: 10.1021/acs.inorgchem.9b03189] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hanft A, Krummenacher I, Lichtenberg C. Cover Feature: Alkali‐Metal Aminotroponiminates: Selectivities and Equilibria in Reversible Radical Coupling of Delocalized π‐Electron Systems (Chem. Eur. J. 51/2019). Chemistry 2019. [DOI: 10.1002/chem.201902906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ramler J, Krummenacher I, Lichtenberg C. Bismutverbindungen in der Radikalkatalyse: Übergangsmetallbismutane ermöglichen thermisch induzierte Cycloisomerisierungen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904365] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Ramler J, Krummenacher I, Lichtenberg C. Bismuth Compounds in Radical Catalysis: Transition Metal Bismuthanes Facilitate Thermally Induced Cycloisomerizations. Angew Chem Int Ed Engl 2019; 58:12924-12929. [PMID: 31166083 DOI: 10.1002/anie.201904365] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Indexed: 11/06/2022]
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Hanft A, Krummenacher I, Lichtenberg C. Alkali‐Metal Aminotroponiminates: Selectivities and Equilibria in Reversible Radical Coupling of Delocalized π‐Electron Systems. Chemistry 2019; 25:11883-11891. [DOI: 10.1002/chem.201901962] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Indexed: 11/10/2022]
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Ramler J, Poater J, Hirsch F, Ritschel B, Fischer I, Bickelhaupt FM, Lichtenberg C. Carbon monoxide insertion at a heavy p-block element: unprecedented formation of a cationic bismuth carbamoyl. Chem Sci 2019; 10:4169-4176. [PMID: 31057745 PMCID: PMC6471928 DOI: 10.1039/c9sc00278b] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 02/27/2019] [Indexed: 12/20/2022] Open
Abstract
The first insertion reaction of CO with a molecular complex of the heavy p-block elements is reported (principal quantum number > 4).
Major advances in the chemistry of 5th and 6th row heavy p-block element compounds have recently uncovered intriguing reactivity patterns towards small molecules such as H2, CO2, and ethylene. However, well-defined, homogeneous insertion reactions with carbon monoxide, one of the benchmark substrates in this field, have not been reported to date. We demonstrate here, that a cationic bismuth amide undergoes facile insertion of CO into the Bi–N bond under mild conditions. This approach grants direct access to the first cationic bismuth carbamoyl species. Its characterization by NMR, IR, and UV/vis spectroscopy, elemental analysis, single-crystal X-ray analysis, cyclic voltammetry, and DFT calculations revealed intriguing properties, such as a reversible electron transfer at the bismuth center and an absorption feature at 353 nm ascribed to a transition involving σ- and π-type orbitals of the bismuth-carbamoyl functionality. A combined experimental and theoretical approach provided insight into the mechanism of CO insertion. The substrate scope could be extended to isonitriles.
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Hanft A, Jürgensen M, Bertermann R, Lichtenberg C. Sodium Aminotroponiminates: Ligand-Induced Disproportionation, Mixed-Metal Compounds, and Exceptional Activity in Polymerization Catalysis. ChemCatChem 2018. [DOI: 10.1002/cctc.201800580] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Hanft A, Lichtenberg C. New Perspectives for Aminotroponiminates: Coordination Chemistry, Redox Behavior, Cooperativity, and Catalysis. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800465] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hanft A, Lichtenberg C. Rationalizing the Effect of Ligand Substitution Patterns on Coordination and Reactivity of Alkali Metal Aminotroponiminates. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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