1
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Ma HZ, Canty AJ, O'Hair RAJ. Electrospray Ionization Tandem Mass Spectrometry and DFT Survey of Copper(I) Ate Complexes Containing Coordinated Borohydride Anions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1443-1452. [PMID: 35749300 DOI: 10.1021/jasms.2c00103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Copper(I) borohydride ate complexes of the type Cat+[XCu(BH4)]- have been previously postulated as intermediates in the reactions of copper salts with borohydride. Negative ion electrospray ionization of an acetonitrile solution of copper(I) phenylacetylide with a 10-fold excess of sodium borohydride (NaBH4) revealed the formation of a diverse range of mononuclear, dinuclear and trinuclear cuprates with different numbers of BH4-, H- and CN- ligands, the latter likely being formed by abstraction of CN- from the acetonitrile solvent. Collision-induced dissociation was used to examine the fragmentation reactions of the following borohydride containing cuprates: [Cu(H)(BH4)]-, [Cu(BH4)2]-, [Cu(BH4)(CN)]-, [Cu2(H)(BH4)2]-, [Cu2(H)2(BH4)]-, [Cu2(BH4)2(CN)]-, [Cu2(H)(BH4)(CN)]-, [Cu3(H)(BH4)3]-, [Cu3(H)2(BH4)2]-, [Cu3(H)3(BH4)]-, [Cu3(BH4)2(CN)2]-, and [Cu3(H)(BH4)2(CN)]-. In all cases, BH3 loss is observed. For many of the dinuclear and trinuclear complexes cluster fragmentation by loss of CuH was also observed. In the case of [Cu2(H)2(BH4)]- and [Cu3(H)3(BH4)]-, loss of H2 was also observed. DFT calculations were used to explore potential structures of the various borohydride-containing cuprates and to predict the overall reaction energetics for the various fragmentation channels.
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Affiliation(s)
- Howard Z Ma
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
| | - Allan J Canty
- School of Natural Sciences - Chemistry, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001, Australia
| | - Richard A J O'Hair
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
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2
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Koszinowski K, Auth T. Modulation of Gas-Phase Lithium Cation Basicities by Microsolvation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1857-1866. [PMID: 31502224 DOI: 10.1007/s13361-019-02312-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 06/10/2023]
Abstract
In contrast to the extensive knowledge of lithium cation affinities and basicities, the thermochemistry of microsolvated lithium cations is much less explored. Here, we determine the relative stabilities of Li(A,B)n+ complexes, n = 2 and 3, by monitoring their gas-phase reactions with A and B substrate molecules, A/B = Me2O, Et2O, tetrahydrofuran, and MeCN, in a three-dimensional quadrupole-ion trap mass spectrometer. Kinetic analysis of the observed ligand displacement reactions affords equilibrium constants, which are then converted into Gibbs reaction energies. In addition, we use high-level quantum chemical calculations to predict the structures and sequential ligand dissociation energies of the homoleptic Li(A)n+ complexes, n = 1-3. As expected, the ligands dissociate more easily from complexes in higher coordination states. However, the very nature of the ligand also matters. Ligands with different steric demands can, thus, invert their relative Li+ affinities depending on the coordination state of the metal center. This finding shows that microsolvation of Li+ can result in specific effects, which are not recognized if the analysis takes into account only simple lithium cation affinities and basicities.
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Affiliation(s)
- Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany.
| | - Thomas Auth
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
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3
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Weske S, Hardin RA, Auth T, O'Hair RAJ, Koszinowski K, Ogle CA. Argentate(i) and (iii) complexes as intermediates in silver-mediated cross-coupling reactions. Chem Commun (Camb) 2018; 54:5086-5089. [PMID: 29708564 DOI: 10.1039/c8cc01707g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the potential of silver to mediate synthetically valuable cross-coupling reactions, the operating mechanisms have remained unknown. Here, we use a combination of rapid-injection NMR spectroscopy, electrospray-ionization mass spectrometry, and quantum chemical calculations to demonstrate that these transformations involve argentate(i) and (iii) complexes as key intermediates.
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Affiliation(s)
- Sebastian Weske
- Institut für Organische und Biomolekulare Chemie, Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany.
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Unravelling the hidden link of lithium halides and application in the synthesis of organocuprates. Nat Commun 2017; 8:14794. [PMID: 28300072 PMCID: PMC5357309 DOI: 10.1038/ncomms14794] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 02/01/2017] [Indexed: 11/18/2022] Open
Abstract
As a versatile metal, copper has demonstrated a wide application in acting as both organometallic reagent and catalyst. Organocuprates are among the most used organometallic reagents in the formation of new carbon–carbon bonds in organic synthesis. Therefore, revealing the real structures of organocuprates in solution is crucial to provide insights into the reactivity of organocuprates. Here we provide several important insights into organocuprate chemistry. The main finding contains the following aspects. The Cu(0) particles were detected via the reduction of CuX by nBuLi or PhLi. The Cu(II) precursors CuX2 (X=Cl, Br) could be used for the preparation of Gilman reagents. In addition, we provide direct evidence for the role and effect of LiX in organocuprate synthesis. Moreover, the EXAFS spectrum provides direct evidence for the exact structure of Li+ CuX2− ate complex in solution. This work not only sheds important light on the role of LiX in the formation of organocuprates but also reports two new routes for organocuprate synthesis. Organocopper species are widely used in synthetic chemistry. Here the authors study the structure of the anionic complex formed from copper salts and lithium halides, showing it to be a key intermediate in the formation of organocuprates, and also show that Cu(II) precursors can form Gilman reagents.
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Büschelberger P, Gärtner D, Reyes‐Rodriguez E, Kreyenschmidt F, Koszinowski K, Jacobi von Wangelin A, Wolf R. Alkene Metalates as Hydrogenation Catalysts. Chemistry 2017; 23:3139-3151. [PMID: 28026060 PMCID: PMC5861671 DOI: 10.1002/chem.201605222] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 11/09/2022]
Abstract
First-row transition-metal complexes hold great potential as catalysts for hydrogenations and related reductive reactions. Homo- and heteroleptic arene/alkene metalates(1-) (M=Co, Fe) are a structurally distinct catalyst class with good activities in hydrogenations of alkenes and alkynes. The first syntheses of the heteroleptic cobaltates [K([18]crown-6)][Co(η4 -cod)(η2 -styrene)2 ] (5) and [K([18]crown-6)][Co(η4 -dct)(η4 -cod)] (6), and the homoleptic complex [K(thf)2 ][Co(η4 -dct)2 ] (7; dct=dibenzo[a,e]cyclooctatetraene, cod=1,5-cyclooctadiene), are reported. For comparison, two cyclopentadienylferrates(1-) were synthesized according to literature procedures. The isolated and fully characterized monoanionic complexes were competent precatalysts in alkene hydrogenations under mild conditions (2 bar H2 , r.t., THF). Mechanistic studies by NMR spectroscopy, ESI mass spectrometry, and poisoning experiments documented the operation of a homogeneous mechanism, which was initiated by facile redox-neutral π-ligand exchange with the substrates followed by H2 activation. The substrate scope of the investigated precatalysts was also extended to polar substrates (ketones and imines).
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Affiliation(s)
- Philipp Büschelberger
- Institute of Inorganic ChemistryUniversity of RegensburgUniversitätsstr. 3193040RegensburgGermany
| | - Dominik Gärtner
- Institute of Organic ChemistryUniversity of Regensburg93040RegensburgGermany
| | | | - Friedrich Kreyenschmidt
- Institut für Organische und Biomolekulare ChemieGeorg-August-Universität GöttingenTammannstr. 237077GöttingenGermany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare ChemieGeorg-August-Universität GöttingenTammannstr. 237077GöttingenGermany
| | | | - Robert Wolf
- Institute of Inorganic ChemistryUniversity of RegensburgUniversitätsstr. 3193040RegensburgGermany
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Kolter M, Koszinowski K. Stability and Unimolecular Reactivity of Palladate(II) Complexes [L n PdR 3 ] - (L=Phosphine, R=Organyl, n=0 and 1). Chemistry 2016; 22:15744-15750. [PMID: 27717040 DOI: 10.1002/chem.201603431] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Indexed: 11/08/2022]
Abstract
The reduction of PdII precatalysts to catalytically active Pd0 species is a key step in many palladium-mediated cross-coupling reactions. Besides phosphines, the stoichiometrically used organometallic reagents can afford this reduction, but do so in a poorly understood way. To elucidate the mechanism of this reaction, we have treated solutions of Pd(OAc)2 and a phosphine ligand L in tetrahydrofuran with RMgCl (R=Ph, Bn, Bu) as well as other organometallic reagents. Analysis of these model systems by electrospray- ionization mass spectrometry found palladate(II) complexes [Ln PdR3 ]- (n=0 and 1), thus pointing to the occurrence of transmetallation reactions. Upon gas-phase fragmentation, the [Ln PdR3 ]- anions preferentially underwent a reductive elimination to yield Pd0 species. The sequence of the transmetallation and reductive elimination, thus, constitutes a feasible mechanism for the reduction of the Pd(OAc)2 precatalyst. Other species of interest observed include the PdIV complex [PdBn5 ]- , which did not fragment via a reductive elimination but lost BnH instead.
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Affiliation(s)
- Marlene Kolter
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany.
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7
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Putau A, Brand H, Koszinowski K. Intermediates Formed in the Reactions of Organocuprates with α,β-Unsaturated Nitriles. Chemistry 2016; 22:12868-76. [PMID: 27461093 DOI: 10.1002/chem.201602451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Indexed: 11/10/2022]
Abstract
Conjugate additions of organocuprates are of outstanding importance for organic synthesis. To improve our mechanistic understanding of these reactions, we have used electrospray ionization mass spectrometry for the identification of the ionic intermediates formed upon the treatment of LiCuR2 ⋅LiCN (R=Me, Bu, Ph) with a series of α,β-unsaturated nitriles. Acrylonitrile, the weakest Michael acceptor included, did not afford any detectable intermediates. Fumaronitrile (FN) yielded adducts of the type Lin-1 Cun R2n (FN)n (-) , n=1-3. When subjected to fragmentation in the gas phase, these adducts were not converted into the conjugate addition products, but re-dissociated into the reactants. In contrast, the reaction with 1,1-dicyanoethylene furnished the products of the conjugate addition without any observable intermediates. Tri- and tetracyanoethylene proved to be quite reactive as well. The presence of several cyano groups in these substrates opened up reaction pathways different from simple conjugate additions, however, and led to dimerization and substitution reactions. Moreover, the gas-phase fragmentation behavior of the species formed from these substrates indicated the occurrence of single-electron transfer processes. Additional quantum-chemical calculations provided insight into the structures and stabilities of the observed intermediates and their consecutive reactions.
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Affiliation(s)
- Aliaksei Putau
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Harald Brand
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany.
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8
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Weske S, Schoop R, Koszinowski K. The Role of Ate Complexes in the Copper-Mediated Trifluoromethylation of Alkynes. Chemistry 2016; 22:11310-6. [PMID: 27385188 DOI: 10.1002/chem.201601261] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 01/30/2023]
Abstract
Trifluoromethylation reactions have recently received increased attention because of the beneficial effect of the trifluoromethyl group on the pharmacological properties of numerous substances. A common method to introduce the trifluoromethyl group employs the Ruppert-Prakash reagent, that is, Si(CH3 )3 CF3 , together with a copper(I) halide. We have applied this method to the trifluoromethylation of aromatic alkynes and used electrospray-ionization mass spectrometry to investigate the mechanism of these reactions in tetrahydrofuran, dichloromethane, and acetonitrile as well as with and without added 1,10-phenanthroline. In the absence of the alkyne component, the homoleptic ate complexes [Cu(CF3 )2 ](-) and [Cu(CF3 )4 ](-) were observed. In the presence of the alkynes RH, the heteroleptic complexes [Cu(CF3 )3 R](-) were detected as well. Upon gas-phase fragmentation, these key intermediates released the cross-coupling products R-CF3 with perfect selectivity. Apparently, the [Cu(CF3 )3 R](-) complexes did not originate from homoleptic cuprate anions, but from unobservable neutral precursors. The present results moreover point to the involvement of oxygen as the oxidizing agent.
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Affiliation(s)
- Sebastian Weske
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany
| | - Ramona Schoop
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany.
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9
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Hirofuji T, Ikeda T, Haino T, Yamamoto Y, Kawachi A. Synthesis of a Pentacene-Type Silaborin via Double Dehydrogenative Cyclization of 1,4-Diboryl-2,5-disilylbenzene. Chemistry 2016; 22:9734-9. [DOI: 10.1002/chem.201600785] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Indexed: 01/15/2023]
Affiliation(s)
- Tatsuya Hirofuji
- Department of Chemistry; Graduate School of Science; Hiroshima University; Kagamiyama 1-3-1 Higashi-Hiroshima 739-8526 Hiroshima Japan
| | - Toshiaki Ikeda
- Department of Chemistry; Graduate School of Science; Hiroshima University; Kagamiyama 1-3-1 Higashi-Hiroshima 739-8526 Hiroshima Japan
| | - Takeharu Haino
- Department of Chemistry; Graduate School of Science; Hiroshima University; Kagamiyama 1-3-1 Higashi-Hiroshima 739-8526 Hiroshima Japan
| | - Yohsuke Yamamoto
- Department of Chemistry; Graduate School of Science; Hiroshima University; Kagamiyama 1-3-1 Higashi-Hiroshima 739-8526 Hiroshima Japan
| | - Atsushi Kawachi
- Department of Chemistry; Graduate School of Science; Hiroshima University; Kagamiyama 1-3-1 Higashi-Hiroshima 739-8526 Hiroshima Japan
- Faculty of Bioscience and Applied Chemistry; Hosei University; Kajino-cho 3-7-2 Koganei 184-8584 Tokyo Japan
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10
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Schnegelsberg C, Bachmann S, Kolter M, Auth T, John M, Stalke D, Koszinowski K. Association and Dissociation of Grignard Reagents RMgCl and Their Turbo Variant RMgCl⋅LiCl. Chemistry 2016; 22:7752-62. [DOI: 10.1002/chem.201600699] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Christoph Schnegelsberg
- Institut für Organische und Biomolekulare Chemie; Georg-August-Universität Göttingen; Tammannstraße 2 37077 Göttingen Germany
| | - Sebastian Bachmann
- Institut für Anorganische Chemie; Georg-August-Universität Göttingen; Tammannstraße 4 37077 Göttingen Germany
| | - Marlene Kolter
- Institut für Organische und Biomolekulare Chemie; Georg-August-Universität Göttingen; Tammannstraße 2 37077 Göttingen Germany
| | - Thomas Auth
- Institut für Organische und Biomolekulare Chemie; Georg-August-Universität Göttingen; Tammannstraße 2 37077 Göttingen Germany
| | - Michael John
- Institut für Organische und Biomolekulare Chemie; Georg-August-Universität Göttingen; Tammannstraße 2 37077 Göttingen Germany
| | - Dietmar Stalke
- Institut für Anorganische Chemie; Georg-August-Universität Göttingen; Tammannstraße 4 37077 Göttingen Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie; Georg-August-Universität Göttingen; Tammannstraße 2 37077 Göttingen Germany
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11
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Molteni R, Bertermann R, Edkins K, Steffen A. An unexpected transmetalation intermediate: isolation and structural characterization of a solely CH3 bridged di-copper(i) complex. Chem Commun (Camb) 2016; 52:5019-22. [PMID: 26983362 DOI: 10.1039/c6cc01510g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Structural characterization of unsupported, two metal centres bridging methyl groups is rare. They have been proposed as transmetalation intermediates in cuprate chemistry, but as yet no structural evidence has been presented. We have isolated a di-copper(i) complex with solely a methyl ligand bridging two Cu(i) atoms, representing a new bonding mode of CH3.
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Affiliation(s)
- Roberto Molteni
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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12
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Tsybizova A, Roithová J. Copper-catalyzed reactions: Research in the gas phase. MASS SPECTROMETRY REVIEWS 2016; 35:85-110. [PMID: 25975564 DOI: 10.1002/mas.21464] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/19/2014] [Indexed: 06/04/2023]
Abstract
Electrospray ionization mass spectrometry (ESI-MS) is becoming an important tool for mechanistic studies in organic and organometallic chemistry. It allows investigation of reaction mixtures including monitoring of reactants, products, and intermediates, studying properties of the intermediates and their reactivity. Studying the reactive species in the gas phase can be advantageously combined with theoretical calculations. This review is focused on ESI-MS studies of copper-catalyzed reactions. Possible effects of the electrospray process on the transfer of the copper complexes to the gas phase are discussed. The plethora of mass spectrometric approaches is demonstrated on copper mediated C-H activations, cross coupling reactions, rearrangements, organocuprate chemistry, and other examples.
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Affiliation(s)
- Alexandra Tsybizova
- Department of Organic Chemistry, Charles University in Prague, Faculty of Science; Hlavova 2030, 128 40 Prague 2, Czech Republic
| | - Jana Roithová
- Department of Organic Chemistry, Charles University in Prague, Faculty of Science; Hlavova 2030, 128 40 Prague 2, Czech Republic
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13
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Böck K, Feil JE, Karaghiosoff K, Koszinowski K. Catalyst Activation, Deactivation, and Degradation in Palladium-Mediated Negishi Cross-Coupling Reactions. Chemistry 2015; 21:5548-60. [DOI: 10.1002/chem.201406408] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 11/11/2022]
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Dieter RK, Picado A. Regio- and stereocontrol in the reactions of α-halo-β,γ-enoates and α-O-phosphono-β,γ-enenitriles with organocuprates. J Org Chem 2014; 79:11125-38. [PMID: 25303237 DOI: 10.1021/jo502111c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of (Z)- and (E)-ethyl 2-chloro-3-octenoate (4a and 17) and (E)- and (Z)-diethyl (1-cyano-2-heptenyl)phosphate (21a and 21b) with organocuprates were investigated as potential substrates for preparing γ-substituted α,β-enoates and enenitriles. In these copper-mediated allylic substitution reactions, the Z-isomer 4a displayed complete regio- and stereoselectivity (i.e., E:Z), while the regio- and stereoselectivity for E-isomer 17 varied as a function of solvent, cuprate reagent, transferable ligand, and cuprate counterion (e.g., Li(+) vs MgX(+)). Excellent selectivities could be achieved with 17 and (n)BuCuCNLi in Et2O. Conditions for improved selectivities in the reactions of allylic cyanophosphates over those previously reported were found. A series of relative rate and competition experiments was performed, and the degree of regio- and stereoselectivity for each system was rationalized in the light of the current mechanistic understanding of cuprate-mediated allylic substitution reactions.
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Affiliation(s)
- R Karl Dieter
- Hunter Laboratory, Department of Chemistry, Clemson University , Clemson, South Carolina 29634-0973, United States
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15
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Khairallah GN, da Silva G, O'Hair RAJ. Molecular salt effects in the gas phase: tuning the kinetic basicity of [HCCLiCl]⁻ and [HCCMgCl₂]⁻ by LiCl and MgCl₂. Angew Chem Int Ed Engl 2014; 53:10979-83. [PMID: 25079912 DOI: 10.1002/anie.201404362] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/11/2014] [Indexed: 11/09/2022]
Abstract
A combination of gas-phase ion-molecule reaction experiments and theoretical kinetic modeling is used to examine how a salt can influence the kinetic basicity of organometallates reacting with water. [HC≡CLiCl](-) reacts with water more rapidly than [HC≡CMgCl2](-), consistent with the higher reactivity of organolithium versus organomagnesium reagents. Addition of LiCl to [HC≡CLiCl](-) or [HC≡CMgCl2](-) enhances their reactivity towards water by a factor of about 2, while addition of MgCl2 to [HC≡CMgCl2](-) enhances its reactivity by a factor of about 4. Ab initio calculations coupled with master equation/RRKM theory kinetic modeling show that these reactions proceed via a mechanism involving formation of a water adduct followed by rearrangement, proton transfer, and acetylene elimination as either discrete or concerted steps. Both the energy and entropy requirements for these elementary steps need to be considered in order to explain the observed kinetics.
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Affiliation(s)
- George N Khairallah
- School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010 (Australia); ARC Centre of Excellence for Free-Radical Chemistry and Biotechnology.
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16
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Khairallah GN, da Silva G, O'Hair RAJ. Molecular Salt Effects in the Gas Phase: Tuning the Kinetic Basicity of [HCCLiCl]−and [HCCMgCl2]−by LiCl and MgCl2. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Bluemke TD, Clegg W, García-Alvarez P, Kennedy AR, Koszinowski K, McCall MD, Russo L, Hevia E. Structural and reactivity insights in Mg–Zn hybrid chemistry: Zn–I exchange and Pd-catalysed cross-coupling applications of aromatic substrates. Chem Sci 2014. [DOI: 10.1039/c4sc01263a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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18
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Rijs NJ, Yoshikai N, Nakamura E, O’Hair RAJ. Unraveling Organocuprate Complexity: Fundamental Insights into Intrinsic Group Transfer Selectivity in Alkylation Reactions. J Org Chem 2014; 79:1320-34. [DOI: 10.1021/jo4027325] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
| | - Naohiko Yoshikai
- Division
of Chemistry and Biological Chemistry, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore 637371
| | - Eiichi Nakamura
- Department
of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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19
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Putau A, Wilken M, Koszinowski K. Ionic Aggregates of Lithium Organocuprates. Chemistry 2013; 19:10992-9. [DOI: 10.1002/chem.201300804] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Indexed: 11/09/2022]
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20
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Khairallah GN, Thum CCL, Lesage D, Tabet JC, O’Hair RAJ. Gas-Phase Formation and Fragmentation Reactions of the Organomagnesates [RMgX2]−. Organometallics 2013. [DOI: 10.1021/om3011917] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Denis Lesage
- Institut Parisien de Chimie Moléculaire, Université Pierre et Marie Curie-Paris 6 (UPMC), UMR 7201- FR2769, Place Jussieu, 75252 Paris Cedex 05, France
| | - Jean-Claude Tabet
- Institut Parisien de Chimie Moléculaire, Université Pierre et Marie Curie-Paris 6 (UPMC), UMR 7201- FR2769, Place Jussieu, 75252 Paris Cedex 05, France
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Blümke TD, Klatt T, Koszinowski K, Knochel P. InCl3-katalysierte Synthese von 1,2-dimetallierten Verbindungen durch direkte Insertion von Aluminium- oder Zinkpulver. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Blümke TD, Klatt T, Koszinowski K, Knochel P. InCl3-Catalyzed Synthesis of 1,2-Dimetallic Compounds by Direct Insertion of Aluminum or Zinc Powder. Angew Chem Int Ed Engl 2012; 51:9926-30. [DOI: 10.1002/anie.201205169] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Indexed: 11/09/2022]
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Dieter RK, Huang Y, Guo F. Regio- and Stereoselectivity in the Reactions of Organometallic Reagents with an Electron-Deficient and an Electron-Rich Vinyloxirane: Applications for Sequential Bis-Allylic Substitution Reactions in the Generation of Vicinal Stereogenic Centers. J Org Chem 2012; 77:4949-67. [DOI: 10.1021/jo300304n] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- R. Karl Dieter
- Hunter Laboratory, Department
of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States
| | - Yaxin Huang
- Hunter Laboratory, Department
of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States
| | - Fenghai Guo
- Hunter Laboratory, Department
of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States
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Jašíková L, Hanikýřová E, Škríba A, Jašík J, Roithová J. Metal-assisted Lossen Rearrangement. J Org Chem 2012; 77:2829-36. [DOI: 10.1021/jo300031f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lucie Jašíková
- Department of Organic Chemistry,
Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843
Prague 2, Czech Republic
| | - Eva Hanikýřová
- Department of Organic Chemistry,
Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843
Prague 2, Czech Republic
| | - Anton Škríba
- Department of Organic Chemistry,
Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843
Prague 2, Czech Republic
| | - Juraj Jašík
- Department of Organic Chemistry,
Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843
Prague 2, Czech Republic
| | - Jana Roithová
- Department of Organic Chemistry,
Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843
Prague 2, Czech Republic
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25
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Jašíková L, Roithová J. Interaction of the Gold(I) Cation Au(PMe3)+ with Unsaturated Hydrocarbons. Organometallics 2012. [DOI: 10.1021/om2012387] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lucie Jašíková
- Department of Organic
Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843 Prague 2, Czech Republic
| | - Jana Roithová
- Department of Organic
Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843 Prague 2, Czech Republic
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27
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Putau A, Brand H, Koszinowski K. Tetraalkylcuprates(III): formation, association, and intrinsic reactivity. J Am Chem Soc 2011; 134:613-22. [PMID: 22129347 DOI: 10.1021/ja209433j] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tetraalkylcuprates are prototypical examples of organocopper(III) species, which remained elusive until their recent detection by NMR spectroscopy. In agreement with the NMR studies, the present electrospray ionization mass spectrometric experiments, as well as supporting electrical conductivity measurements, indicate that LiCuMe(2)·LiCN reacts with a series of alkyl halides RX. The resulting Li(+)Me(2)CuR(CN)(-) intermediates then afford the observable Me(3)CuR(-) tetraalkylcuprate anions upon Me/CN exchanges with added MeLi. In contrast, the reactions of LiCuMe(2)·LiCN with neopentyl iodide and various aryl halides give rise to halogen-copper exchanges. Concentration- and solvent-dependent studies suggest that lithium tetraalkylcuprates are not fully dissociated in ethereal solvents, but partly form Li(+)Me(3)CuR(-) contact ion pairs and presumably also triple ions LiMe(6)Cu(2)R(2)(-). According to theoretical calculations, these triple ions consist of two square-planar Me(3)CuR(-) subunits binding to a central Li(+) ion. Upon fragmentation in the gas phase, the mass-selected Me(3)CuR(-) anions undergo reductive elimination, yielding both the cross-coupling products MeR and the homocoupling product Me(2). The branching between these two fragmentation channels markedly depends on the nature of the alkyl substituent R. The triple ions LiMe(6)Cu(2)R(2)(-) (as well as their mixed analogues LiMe(6)Cu(2)R(R')(-)) also afford both cross-coupling and homocoupling products upon fragmentation, but strongly favor the former. On the basis of theoretical calculations, we rationalize this prevalence of cross-coupling by the preferential interaction of the central Li(+) ion of the triple ions with two Me groups of each Me(3)CuR(-) subunit, which thereby effectively blocks the homocoupling channel. Our results thus show how a Li(+) counterion can alter the reactivity of an organocopper species at the molecular level.
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Affiliation(s)
- Aliaksei Putau
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany
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28
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Affiliation(s)
- Naohiko Yoshikai
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Eiichi Nakamura
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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