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Riddlestone IM, Kraft A, Schaefer J, Krossing I. Die Schöne (WCA) und das (kationische) Biest: Neues aus der Chemie von und mit schwach koordinierenden Anionen. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201710782] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ian M. Riddlestone
- Institut für Anorganische und Analytische Chemie; Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Anne Kraft
- Institut für Anorganische und Analytische Chemie; Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Julia Schaefer
- Institut für Anorganische und Analytische Chemie; Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie; Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
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52
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Riddlestone IM, Kraft A, Schaefer J, Krossing I. Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions. Angew Chem Int Ed Engl 2018; 57:13982-14024. [PMID: 29266644 DOI: 10.1002/anie.201710782] [Citation(s) in RCA: 251] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Indexed: 12/11/2022]
Abstract
This Review gives a comprehensive overview of the most topical weakly coordinating anions (WCAs) and contains information on WCA design, stability, and applications. As an update to the 2004 review, developments in common classes of WCA are included. Methods for the incorporation of WCAs into a given system are discussed and advice given on how to best choose a method for the introduction of a particular WCA. A series of starting materials for a large number of WCA precursors and references are tabulated as a useful resource when looking for procedures to prepare WCAs. Furthermore, a collection of scales that allow the performance of a WCA, or its underlying Lewis acid, to be judged is collated with some advice on how to use them. The examples chosen to illustrate WCA developments are taken from a broad selection of topics where WCAs play a role. In addition a section focusing on transition metal and catalysis applications as well as supporting electrolytes is also included.
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Affiliation(s)
- Ian M Riddlestone
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Anne Kraft
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Julia Schaefer
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
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53
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Pahl J, Brand S, Elsen H, Harder S. Highly Lewis acidic cationic alkaline earth metal complexes. Chem Commun (Camb) 2018; 54:8685-8688. [PMID: 29892727 DOI: 10.1039/c8cc04083d] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cationic Lewis base-free β-diketiminate (BDI) complexes of Mg and Ca have been isolated as their B(C6F5)4- salts. The cation (BDI)Mg+ shows an extraordinarily strong Lewis acidity that can compete with strong Lewis acids like B(C6F5)3 and (BDI)AlMe+. Its highly electrophilic nature is exemplified by isolation of an 3-hexyne adduct.
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Affiliation(s)
- Jürgen Pahl
- Inorganic and Organometallic Chemistry, University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany.
| | - Steffen Brand
- Inorganic and Organometallic Chemistry, University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany.
| | - Holger Elsen
- Inorganic and Organometallic Chemistry, University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany.
| | - Sjoerd Harder
- Inorganic and Organometallic Chemistry, University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany.
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54
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Hoshimoto Y, Kinoshita T, Hazra S, Ohashi M, Ogoshi S. Main-Group-Catalyzed Reductive Alkylation of Multiply Substituted Amines with Aldehydes Using H 2. J Am Chem Soc 2018; 140:7292-7300. [PMID: 29790343 DOI: 10.1021/jacs.8b03626] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Given the growing demand for green and sustainable chemical processes, the catalytic reductive alkylation of amines with main-group catalysts of low toxicity and molecular hydrogen as the reductant would be an ideal method to functionalize amines. However, such a process remains challenging. Herein, a novel reductive alkylation system using H2 is presented, which proceeds via a tandem reaction that involves the B(2,6-Cl2C6H3)( p-HC6F4)2-catalyzed formation of an imine and the subsequent hydrogenation of this imine catalyzed by a frustrated Lewis pair (FLP). This reductive alkylation reaction generates H2O as the sole byproduct and directly functionalizes amines that bear a remarkably wide range of substituents including carboxyl, hydroxyl, additional amino, primary amide, and primary sulfonamide groups. The synthesis of isoindolinones and aminophthalic anhydrides has also been achieved by a one-pot process that consists of a combination of the present reductive alkylation with an intramolecular amidation and intramolecular dehydration reactions, respectively. The reaction showed a zeroth-order and a first-order dependence on the concentration of an imine intermediate and B(2,6-Cl2C6H3)( p-HC6F4)2, respectively. In addition, the reaction progress was significantly affected by the concentration of H2. These results suggest a possible mechanism in which the heterolysis of H2 is facilitated by the FLP comprising THF and B(2,6-Cl2C6H3)( p-HC6F4)2.
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55
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Scott DJ, Fuchter MJ, Ashley AE. Designing effective 'frustrated Lewis pair' hydrogenation catalysts. Chem Soc Rev 2018; 46:5689-5700. [PMID: 28692084 DOI: 10.1039/c7cs00154a] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The past decade has seen the subject of transition metal-free catalytic hydrogenation develop incredibly rapidly, transforming from a largely hypothetical possibility to a well-established field that can be applied to the reduction of a diverse variety of functional groups under mild conditions. This remarkable change is principally attributable to the development of so-called 'frustrated Lewis pairs': unquenched combinations of bulky Lewis acids and bases whose dual reactivity can be exploited for the facile activation of otherwise inert chemical bonds. While a number of comprehensive reviews into frustrated Lewis pair chemistry have been published in recent years, this tutorial review aims to provide a focused guide to the development of efficient FLP hydrogenation catalysts, through identification and consideration of the key factors that govern their effectiveness. Following discussion of these factors, their importance will be illustrated using a case study from our own research, namely the development of FLP protocols for successful hydrogenation of aldehydes and ketones, and for related moisture-tolerant hydrogenation.
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Affiliation(s)
- Daniel J Scott
- Department of Chemistry, Imperial College London, SW7 2AZ, UK.
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56
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Xing JY, Buffet JC, Rees NH, Nørby P, O'Hare D. Hydrogen cleavage by solid-phase frustrated Lewis pairs. Chem Commun (Camb) 2018; 52:10478-81. [PMID: 27463124 DOI: 10.1039/c6cc04937k] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the direct synthesis of a solid-phase frustrated Lewis pair (s-FLP) by combining a silica-supported Lewis acid ([triple bond, length as m-dash]SiOB(C6F5)2, s-BCF) with a Lewis base (tri-tert-butylphosphine, (t)Bu3P) to give [[triple bond, length as m-dash]SiOB(C6F5)2][(t)Bu3P]. Reaction of this s-FLP with H2 under mild conditions led to heterolytic H-H bond cleavage and the formation of [[triple bond, length as m-dash]SiOB(H)(C6F5)2][(t)Bu3PH].
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Affiliation(s)
- Jun-Yi Xing
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Jean-Charles Buffet
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Nicholas H Rees
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Peter Nørby
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Dermot O'Hare
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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57
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Maskey R, Schädler M, Legler C, Greb L. Bis(perchlorocatecholato)silane-A Neutral Silicon Lewis Super Acid. Angew Chem Int Ed Engl 2018; 57:1717-1720. [PMID: 29240282 DOI: 10.1002/anie.201712155] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Indexed: 01/26/2023]
Abstract
No neutral silicon Lewis super acids are known to date. We report on the synthesis of bis(perchlorocatecholato)silane and verify its Lewis super acidity by computation (DLPNO-CCSD(T)) and experiment (fluoride abstraction from SbF6- ). The exceptional affinity towards donors is further demonstrated by, for example, the characterization of an unprecedented SiO4 F2 dianion and applied in the first hydrodefluorination reaction catalyzed by a neutral silicon Lewis acid. Given the strength and convenient access to this new Lewis acid, versatile applications might be foreseen.
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Affiliation(s)
- Rezisha Maskey
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Marcel Schädler
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Claudia Legler
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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58
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Maskey R, Schädler M, Legler C, Greb L. Bis(perchlorocatecholato)silan - eine neutrale Silicium-Lewis-Supersäure. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201712155] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Rezisha Maskey
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Marcel Schädler
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Claudia Legler
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Lutz Greb
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
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59
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LaFortune JHW, Szkop KM, Farinha FE, Johnstone TC, Postle S, Stephan DW. Probing steric influences on electrophilic phosphonium cations: a comparison of [(3,5-(CF3)2C6H3)3PF]+ and [(C6F5)3PF]+. Dalton Trans 2018; 47:11411-11419. [DOI: 10.1039/c8dt02594k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electrophilic phosphonium cation (EPC) salt [(3,5-(CF3)2C6H3)3PF][B(C6F5)4] (2) can display catalytic activity greater than its thermodynamic acidity would suggest. The role of steric factors is explored.
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Affiliation(s)
| | - Kevin M. Szkop
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
| | - Farah E. Farinha
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
| | | | - Shawn Postle
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
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60
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Fasano V, LaFortune JHW, Bayne JM, Ingleson MJ, Stephan DW. Air- and water-stable Lewis acids: synthesis and reactivity of P-trifluoromethyl electrophilic phosphonium cations. Chem Commun (Camb) 2018; 54:662-665. [DOI: 10.1039/c7cc09128a] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Electrophilic phosphonium cations (EPCs) containing a –CF3 group are stable to air, water, alcohol and strong Brønsted acid and function as Lewis acid catalysts without requiring anhydrous reaction conditions.
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Affiliation(s)
- V. Fasano
- School of Chemistry, University of Manchester
- UK
- Department of Chemistry, University of Toronto
- Canada
| | | | - J. M. Bayne
- Department of Chemistry, University of Toronto
- Canada
| | | | - D. W. Stephan
- Department of Chemistry, University of Toronto
- Canada
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61
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Heshmat M, Privalov T. Theory-Based Extension of the Catalyst Scope in the Base-Catalyzed Hydrogenation of Ketones: RCOOH-Catalyzed Hydrogenation of Carbonyl Compounds with H 2 Involving a Proton Shuttle. Chemistry 2017; 23:18193-18202. [PMID: 28981175 DOI: 10.1002/chem.201702149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Indexed: 11/09/2022]
Abstract
As an extension of the reaction mechanism describing the base-catalyzed hydrogenation of ketones according to Berkessel et al., we use a standard methodology for transition-state (TS) calculations in order to check the possibility of heterolytic cleavage of H2 at the ketone's carbonyl carbon atom, yielding one-step hydrogenation path with involvement of carboxylic acid as a catalyst. As an extension of the catalyst scope in the base-catalyzed hydrogenation of ketones, our mechanism involves a molecule with a labile proton and a Lewis basic oxygen atom as a catalyst-for example, R-C(=O)OH carboxylic acids-so that the heterolytic cleavage of H2 could take place between the Lewis basic oxygen atom of a carboxylic acid and the electrophilic (Lewis acidic) carbonyl carbon of a ketone/aldehyde. According to our TS calculations, protonation of a ketone/aldehyde by a proton shuttle (hydrogen bond) facilitates the hydride-type attack on the ketone's carbonyl carbon atom in the process of the heterolytic cleavage of H2 . Ketones with electron-rich and electron-withdrawing substituents in combination with a few carboxylic and amino acids-in total, 41 substrate-catalyst couples-have been computationally evaluated in this article and the calculated reaction barriers are encouragingly moderate for many of the considered substrate-catalyst couples.
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Affiliation(s)
- Mojgan Heshmat
- Department of Organic Chemistry, Stockholm University, Stockholm, 10691, Sweden
| | - Timofei Privalov
- Department of Organic Chemistry, Stockholm University, Stockholm, 10691, Sweden
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62
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63
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Dorkó É, Kótai B, Földes T, Gyömöre Á, Pápai I, Soós T. Correlating electronic and catalytic properties of frustrated Lewis pairs for imine hydrogenation. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.04.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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64
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Heshmat M, Privalov T. Testing the nature of reaction coordinate describing interaction of H2 with carbonyl carbon, activated by Lewis acid complexation, and the Lewis basic solvent: A Born-Oppenheimer molecular dynamics study with explicit solvent. J Chem Phys 2017; 147:094302. [DOI: 10.1063/1.4999708] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mojgan Heshmat
- Department of Organic Chemistry, Stockholm University, Stockholm 10691, Sweden
| | - Timofei Privalov
- Department of Organic Chemistry, Stockholm University, Stockholm 10691, Sweden
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65
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Xu M, Possart J, Waked AE, Roy J, Uhl W, Stephan DW. Halogenated triphenylgallium and -indium in frustrated Lewis pair activations and hydrogenation catalysis. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2017.0014. [PMID: 28739969 PMCID: PMC5540843 DOI: 10.1098/rsta.2017.0014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/12/2017] [Indexed: 06/07/2023]
Abstract
The Lewis acids Ga(C6F5)3, In(C6F5)3 and Ga(C6Cl5)3 are prepared and their Lewis acidity has been probed experimentally and computationally. The species Ga(C6F5)3 and In(C6F5)3 in conjunction with phosphine donors are shown to heterolytically split H2 and catalyse the hydrogenation of an imine. In addition, frustrated Lewis pairs (FLPs) derived from Ga(C6F5)3 and In(C6F5)3 and phosphines react with diphenyldisulfide to phosphoniumgallates or indates of the form [tBu3PSPh][PhSE(C6F5)3] and [tBu3PSPh][(μ-SPh)(E(C6F5)3)2] (E = Ga, In). The potential of the FLPs based on Ga(C6F5)3, In(C6F5)3 and Ga(C6Cl5)3 and phosphines is also shown in reactions with phenylacetylene to give pure or mixtures of the products [tBu3PH][PhCCE(C6X5)3] and R3P(Ph)C=C(H)E(C6X5)3 A number of these species are crystallographically characterized. The implications for the use of these species in FLP chemistry are considered.This article is part of the themed issue 'Frustrated Lewis pair chemistry'.
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Affiliation(s)
- Maotong Xu
- Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario, Canada M5H 3H6
| | - Josephine Possart
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstraße 28-30, 48149 Münster, Germany
| | - Alexander E Waked
- Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario, Canada M5H 3H6
| | - Julie Roy
- Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario, Canada M5H 3H6
| | - Werner Uhl
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstraße 28-30, 48149 Münster, Germany
| | - Douglas W Stephan
- Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario, Canada M5H 3H6
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66
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Hecht R, Kade J, Schmidt D, Nowak-Król A. n-Channel Organic Semiconductors Derived from Air-Stable Four-Coordinate Boron Complexes of Substituted Thienylthiazoles. Chemistry 2017; 23:11620-11628. [DOI: 10.1002/chem.201701922] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Indexed: 02/04/2023]
Affiliation(s)
- Reinhard Hecht
- Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI); Universität Würzburg; Theodor-Boveri-Weg 97074 Würzburg Germany
- Institut für Organische Chemie; Universität Würzburg; Am Hubland 97074 Würzburg Germany
| | - Juliane Kade
- Institut für Organische Chemie; Universität Würzburg; Am Hubland 97074 Würzburg Germany
| | - David Schmidt
- Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI); Universität Würzburg; Theodor-Boveri-Weg 97074 Würzburg Germany
- Institut für Organische Chemie; Universität Würzburg; Am Hubland 97074 Würzburg Germany
| | - Agnieszka Nowak-Król
- Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI); Universität Würzburg; Theodor-Boveri-Weg 97074 Würzburg Germany
- Institut für Organische Chemie; Universität Würzburg; Am Hubland 97074 Würzburg Germany
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67
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Liu L(L, Cao LL, Shao Y, Ménard G, Stephan DW. A Radical Mechanism for Frustrated Lewis Pair Reactivity. Chem 2017. [DOI: 10.1016/j.chempr.2017.05.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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68
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Liu LL, Cao LL, Shao Y, Stephan DW. Single Electron Delivery to Lewis Pairs: An Avenue to Anions by Small Molecule Activation. J Am Chem Soc 2017; 139:10062-10071. [PMID: 28654746 DOI: 10.1021/jacs.7b05120] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single electron transfer (SET) reactions are effected by the combination of a Lewis acid (e.g., E(C6F5)3 E = B or Al) with a small molecule substrate and decamethylferrocene (Cp*2Fe). Initially, the corresponding reactions of (PhS)2 and (PhTe)2 were shown to give the species [Cp*2Fe][PhSB(C6F5)3] 1 and [Cp*2Fe][(μ-PhS)(Al(C6F5)3)2] 2 and [Cp*2Fe][(μ-PhTe)(Al(C6F5)3)2] 3, respectively. Analogous reactions with di-tert-butyl peroxide yielded [Cp*2Fe][(μ-HO)(B(C6F5)3)2] 4 with isobutene while with benzoyl peroxide afforded [Cp*2Fe][PhC(O)OE(C6F5)3] (E = B 5, Al 6). Evidence for a radical pathway was provided by the reaction of Ph3SnH and p-quinone afforded [Cp*2Fe][HB(C6F5)3] 7 and [Cp*2Fe]2[(μ-O2C6H4)(E(C6F5)3)2] (E = B 8, Al 9). In addition, the reaction of TEMPO with Lewis acid and Cp*2Fe afforded [Cp*2Fe][(C5H6Me4NOE(C6F5)3] (E = B 10, Al 11). Finally, reactions with O2, Se, Te and S8 gave [Cp*2Fe]2[((C6F5)2Al(μ-O)Al(C6F5)3)2]2 12, [Cp*2Fe]2[((C6F5)2Al(μ-Se)Al(C6F5)3)2]2 13, [Cp*2Fe][(μ-Te)2(Al(C6F5)2)3] 14 and [Cp*2Fe]2[(μ-S7)B(C6F5)3)2] 15, respectively. The mechanisms of these SET reactions are discussed, and the ramifications are considered.
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Affiliation(s)
- Liu Leo Liu
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Levy L Cao
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Yue Shao
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Douglas W Stephan
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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69
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Dorkó É, Szabó M, Kótai B, Pápai I, Domján A, Soós T. Expanding the Boundaries of Water-Tolerant Frustrated Lewis Pair Hydrogenation: Enhanced Back Strain in the Lewis Acid Enables the Reductive Amination of Carbonyls. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201703591] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Éva Dorkó
- Institute of Organic Chemistry; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
| | - Márk Szabó
- NMR Research Laboratory of IC; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
| | - Bianka Kótai
- Institute of Organic Chemistry; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
| | - Imre Pápai
- Institute of Organic Chemistry; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
| | - Attila Domján
- NMR Research Laboratory of IC; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
| | - Tibor Soós
- Institute of Organic Chemistry; Hungarian Academy of Sciences; Research Centre for Natural Sciences; Magyar tudósok körútja 2 1117 Budapest Hungary
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70
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Dorkó É, Szabó M, Kótai B, Pápai I, Domján A, Soós T. Expanding the Boundaries of Water-Tolerant Frustrated Lewis Pair Hydrogenation: Enhanced Back Strain in the Lewis Acid Enables the Reductive Amination of Carbonyls. Angew Chem Int Ed Engl 2017; 56:9512-9516. [PMID: 28591474 DOI: 10.1002/anie.201703591] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/21/2017] [Indexed: 12/20/2022]
Abstract
The development of a boron/nitrogen-centered frustrated Lewis pair (FLP) with remarkably high water tolerance is presented. As systematic steric tuning of the boron-based Lewis acid (LA) component revealed, the enhanced back-strain makes water binding increasingly reversible in the presence of relatively strong base. This advance allows the limits of FLP's hydrogenation to be expanded, as demonstrated by the FLP reductive amination of carbonyls. This metal-free catalytic variant displays a notably broad chemoselectivity and generality.
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Affiliation(s)
- Éva Dorkó
- Institute of Organic Chemistry, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Márk Szabó
- NMR Research Laboratory of IC, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Bianka Kótai
- Institute of Organic Chemistry, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Imre Pápai
- Institute of Organic Chemistry, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Attila Domján
- NMR Research Laboratory of IC, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Tibor Soós
- Institute of Organic Chemistry, Hungarian Academy of Sciences, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
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71
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Mane MV, Vanka K. Less Frustration, More Activity-Theoretical Insights into Frustrated Lewis Pairs for Hydrogenation Catalysis. ChemCatChem 2017. [DOI: 10.1002/cctc.201700289] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Manoj V. Mane
- Physical Chemistry Division; National Chemical Laboratory; Dr. Homi Bhabha Road Pashan Pune Maharashtra India
- Center for Catalytic Hydrocarbon Functionalizations; Institute of Basic Science (IBS); Department of Chemistry; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 34141 Republic of Korea
| | - Kumar Vanka
- Physical Chemistry Division; National Chemical Laboratory; Dr. Homi Bhabha Road Pashan Pune Maharashtra India
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72
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73
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Körte LA, Schwabedissen J, Soffner M, Blomeyer S, Reuter CG, Vishnevskiy YV, Neumann B, Stammler HG, Mitzel NW. Tris(perfluorotolyl)borane-A Boron Lewis Superacid. Angew Chem Int Ed Engl 2017; 56:8578-8582. [DOI: 10.1002/anie.201704097] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Indexed: 01/23/2023]
Affiliation(s)
- Leif A. Körte
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Jan Schwabedissen
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Marcel Soffner
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Sebastian Blomeyer
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Christian G. Reuter
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Yury V. Vishnevskiy
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | | | - Hans-Georg Stammler
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Norbert W. Mitzel
- Lehrstuhl für Anorganische Chemie und Strukturchemie and Centrum für Molekulare Materialien CM 2; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
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74
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Fasano V, Ingleson MJ. Expanding Water/Base Tolerant Frustrated Lewis Pair Chemistry to Alkylamines Enables Broad Scope Reductive Aminations. Chemistry 2017; 23:2217-2224. [PMID: 27977048 PMCID: PMC5396349 DOI: 10.1002/chem.201605466] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Indexed: 01/05/2023]
Abstract
Lower Lewis acidity boranes demonstrate greater tolerance to combinations of water/strong Brønsted bases than B(C6 F5 )3 , this enables Si-H bond activation by a frustrated Lewis pair (FLP) mechanism to proceed in the presence of H2 O/alkylamines. Specifically, BPh3 has improved water tolerance in the presence of alkylamines as the Brønsted acidic adduct H2 O-BPh3 does not undergo irreversible deprotonation with aliphatic amines in contrast to H2 O-B(C6 F5 )3 . Therefore BPh3 is a catalyst for the reductive amination of aldehydes and ketones with alkylamines using silanes as reductants. A range of amines inaccessible using B(C6 F5 )3 as catalyst, were accessible by reductive amination catalysed by BPh3 via an operationally simple methodology requiring no purification of BPh3 or reagents/solvent. BPh3 has a complementary reductive amination scope to B(C6 F5 )3 with the former not an effective catalyst for the reductive amination of arylamines, while the latter is not an effective catalyst for the reductive amination of alkylamines. This disparity is due to the different pKa values of the water-borane adducts and the greater susceptibility of BPh3 species towards protodeboronation. An understanding of the deactivation processes occurring using B(C6 F5 )3 and BPh3 as reductive amination catalysts led to the identification of a third triarylborane, B(3,5-Cl2 C6 H3 )3 , that has a broader substrate scope being able to catalyse the reductive amination of both aryl and alkyl amines with carbonyls.
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Affiliation(s)
- Valerio Fasano
- School of ChemistryUniversity of ManchesterManchesterM13 9PLUK
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75
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Grandl M, Rudolf B, Sun Y, Bechtel DF, Pierik AJ, Pammer F. Intramolecular N→B Coordination as a Stabilizing Scaffold for π-Conjugated Radical Anions with Tunable Redox Potentials. Organometallics 2017. [DOI: 10.1021/acs.organomet.6b00916] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Markus Grandl
- Institute
of Organic Chemistry II and Advanced Materials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Benjamin Rudolf
- Institute
of Organic Chemistry II and Advanced Materials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Yu Sun
- Fachbereich
Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse
54, 67663 Kaiserslautern, Germany
| | - Dominique F. Bechtel
- Fachbereich
Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse
54, 67663 Kaiserslautern, Germany
| | - Antonio J. Pierik
- Fachbereich
Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse
54, 67663 Kaiserslautern, Germany
| | - Frank Pammer
- Institute
of Organic Chemistry II and Advanced Materials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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76
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Fasano V, Radcliffe JE, Curless LD, Ingleson MJ. N-Methyl-Benzothiazolium Salts as Carbon Lewis Acids for Si-H σ-Bond Activation and Catalytic (De)hydrosilylation. Chemistry 2017; 23:187-193. [PMID: 27780294 PMCID: PMC5396135 DOI: 10.1002/chem.201604613] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Indexed: 11/08/2022]
Abstract
N-Me-Benzothiazolium salts are introduced as a new family of Lewis acids able to activate Si-H σ bonds. These carbon-centred Lewis acids were demonstrated to have comparable Lewis acidity towards hydride as found for the triarylboranes widely used in Si-H σ-bond activation. However, they display low Lewis acidity towards hard Lewis bases such as Et3 PO and H2 O in contrast to triarylboranes. The N-Me-benzothiazolium salts are effective catalysts for a range of hydrosilylation and dehydrosilylation reactions. Judicious selection of the C2 aryl substituent in these cations enables tuning of the steric and electronic environment around the electrophilic centre to generate more active catalysts. Finally, related benzoxazolium and benzimidazolium salts were found also to be active for Si-H bond activation and as catalysts for the hydrosilylation of imines.
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Affiliation(s)
- Valerio Fasano
- School of ChemistryUniversity of ManchesterManchesterM13 9PLUK
| | | | - Liam D. Curless
- School of ChemistryUniversity of ManchesterManchesterM13 9PLUK
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77
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Abstract
The synthesis, stability and catalytic reactivity of borocations are described in the context of their reaction in frustrated Lewis pair-type processes.
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Affiliation(s)
| | - C. M. Crudden
- Department of Chemistry
- Queen's University
- Kingston
- Canada
- Institute of Transformative Bio-Molecules (WPI-ITbM)
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78
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Scott DJ, Phillips NA, Sapsford JS, Deacy AC, Fuchter MJ, Ashley AE. Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid. Angew Chem Int Ed Engl 2016; 55:14738-14742. [PMID: 27774711 PMCID: PMC5129554 DOI: 10.1002/anie.201606639] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/05/2016] [Indexed: 12/19/2022]
Abstract
Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3 SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3 Sn+ , and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture.
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Affiliation(s)
- Daniel J. Scott
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
| | | | | | - Arron C. Deacy
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
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79
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Scott DJ, Phillips NA, Sapsford JS, Deacy AC, Fuchter MJ, Ashley AE. Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606639] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Daniel J. Scott
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
| | | | | | - Arron C. Deacy
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
| | | | - Andrew E. Ashley
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
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80
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Smith MF, Cassidy SJ, Adams IA, Vasiliu M, Gerlach DL, Dixon DA, Rupar PA. Substituent Effects on the Properties of Borafluorenes. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00537] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Mallory F. Smith
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - S. Joel Cassidy
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - Ian A. Adams
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - Monica Vasiliu
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - Deidra L. Gerlach
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - David A. Dixon
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
| | - Paul A. Rupar
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0036, United States
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81
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Blagg RJ, Simmons TR, Hatton GR, Courtney JM, Bennett EL, Lawrence EJ, Wildgoose GG. Novel B(Ar')2(Ar'') hetero-tri(aryl)boranes: a systematic study of Lewis acidity. Dalton Trans 2016; 45:6032-43. [PMID: 26541517 DOI: 10.1039/c5dt03854e] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A series of homo- and hetero-tri(aryl)boranes incorporating pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, and pentachlorophenyl groups, four of which are novel species, have been studied as the acidic component of frustrated Lewis pairs for the heterolytic cleavage of H2. Under mild conditions eight of these will cleave H2; the rate of cleavage depending on both the electrophilicity of the borane and the steric bulk around the boron atom. Electrochemical studies allow comparisons of the electrophilicity with spectroscopic measurements of Lewis acidity for different series of boranes. Discrepancies in the correlation between these two types of measurements, combined with structural characterisation of each borane, reveal that the twist of the aryl rings with respect to the boron-centred trigonal plane is significant from both a steric and electronic perspective, and is an important consideration in the design of tri(aryl)boranes as Lewis acids.
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Affiliation(s)
- Robin J Blagg
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Trevor R Simmons
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Georgina R Hatton
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - James M Courtney
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Elliot L Bennett
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Elliot J Lawrence
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
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82
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Yamamoto K, Takagi A, Hada M, Taniwaki R, Mizutani T, Kimura Y, Takao Y, Moriwaki K, Matsumoto F, Ito T, Iwai T, Hida K, Mizuno T, Ohno T. Synthesis and optoelectronic properties of hexachloro- and hexaiodosubnaphthalocyanines as organic electronic materials. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.06.064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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83
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Engesser TA, Lichtenthaler MR, Schleep M, Krossing I. Reactive p-block cations stabilized by weakly coordinating anions. Chem Soc Rev 2016; 45:789-899. [PMID: 26612538 PMCID: PMC4758321 DOI: 10.1039/c5cs00672d] [Citation(s) in RCA: 222] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 12/12/2022]
Abstract
The chemistry of the p-block elements is a huge playground for fundamental and applied work. With their bonding from electron deficient to hypercoordinate and formally hypervalent, the p-block elements represent an area to find terra incognita. Often, the formation of cations that contain p-block elements as central ingredient is desired, for example to make a compound more Lewis acidic for an application or simply to prove an idea. This review has collected the reactive p-block cations (rPBC) with a comprehensive focus on those that have been published since the year 2000, but including the milestones and key citations of earlier work. We include an overview on the weakly coordinating anions (WCAs) used to stabilize the rPBC and give an overview to WCA selection, ionization strategies for rPBC-formation and finally list the rPBC ordered in their respective group from 13 to 18. However, typical, often more organic ion classes that constitute for example ionic liquids (imidazolium, ammonium, etc.) were omitted, as were those that do not fulfill the - naturally subjective -"reactive"-criterion of the rPBC. As a rule, we only included rPBC with crystal structure and only rarely refer to important cations published without crystal structure. This collection is intended for those who are simply interested what has been done or what is possible, as well as those who seek advice on preparative issues, up to people having a certain application in mind, where the knowledge on the existence of a rPBC that might play a role as an intermediate or active center may be useful.
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Affiliation(s)
- Tobias A. Engesser
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF) , Universität Freiburg , Albertstr. 21 , 79104 Freiburg , Germany .
| | - Martin R. Lichtenthaler
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF) , Universität Freiburg , Albertstr. 21 , 79104 Freiburg , Germany .
| | - Mario Schleep
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF) , Universität Freiburg , Albertstr. 21 , 79104 Freiburg , Germany .
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF) , Universität Freiburg , Albertstr. 21 , 79104 Freiburg , Germany .
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84
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Postle S, Podgorny V, Stephan DW. Electrophilic phosphonium cations (EPCs) with perchlorinated-aryl substituents: towards air-stable phosphorus-based Lewis acid catalysts. Dalton Trans 2016; 45:14651-7. [DOI: 10.1039/c6dt01339b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A series of fluorophosphonium cations incorporating (C6Cl5) substituents, [Ph2PF(C6Cl5)][B(C6F5)4] 8, [PhPF(C6Cl5)2][B(C6F5)4] 9, and [(C6F5)PF(C6Cl5)2][B(C6F5)4] 10, were prepared and tested for air stability and catalytic activity.
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Affiliation(s)
- Shawn Postle
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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85
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Abstract
The first 1 : 1 : 1 hetero-tri(aryl)borane cleaves H2 with various Lewis bases, and its electrochemistry is studied.
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86
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Inkpen MS, Du S, Hildebrand M, White AJP, Harrison NM, Albrecht T, Long NJ. The Unusual Redox Properties of Fluoroferrocenes Revealed through a Comprehensive Study of the Haloferrocenes. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00811] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael S. Inkpen
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, U.K
| | - Shuoren Du
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, U.K
- College
of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | | | | | | | - Tim Albrecht
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, U.K
| | - Nicholas J. Long
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, U.K
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87
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Scott DJ, Simmons TR, Lawrence EJ, Wildgoose GG, Fuchter MJ, Ashley AE. Facile Protocol for Water-Tolerant "Frustrated Lewis Pair"-Catalyzed Hydrogenation. ACS Catal 2015; 5:5540-5544. [PMID: 26523238 PMCID: PMC4613738 DOI: 10.1021/acscatal.5b01417] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/11/2015] [Indexed: 12/02/2022]
Abstract
![]()
Despite rapid advances in the field
of metal-free, “frustrated
Lewis pair” (FLP)-catalyzed hydrogenation, the need for strictly
anhydrous reaction conditions has hampered wide-scale uptake of this
methodology. Herein, we report that, despite the generally perceived
moisture sensitivity of FLPs, 1,4-dioxane solutions of B(C6F5)3 actually show appreciable moisture tolerance
and can catalyze hydrogenation of a range of weakly basic substrates
without the need for rigorously inert conditions. In particular, reactions
can be performed directly in commercially available nonanhydrous solvents
without subsequent drying or use of internal desiccants.
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Affiliation(s)
- Daniel J. Scott
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Trevor R. Simmons
- Energy
Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Elliot J. Lawrence
- Energy
Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Gregory G. Wildgoose
- Energy
Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Matthew J. Fuchter
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Andrew E. Ashley
- Department
of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
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88
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Gyömöre Á, Bakos M, Földes T, Pápai I, Domján A, Soós T. Moisture-Tolerant Frustrated Lewis Pair Catalyst for Hydrogenation of Aldehydes and Ketones. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01299] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Ádám Gyömöre
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Mária Bakos
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Tamás Földes
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Imre Pápai
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Attila Domján
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Tibor Soós
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117 Budapest, Hungary
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89
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Chitnis SS, Robertson APM, Burford N, Patrick BO, McDonald R, Ferguson MJ. Bipyridine complexes of E 3+ (E = P, As, Sb, Bi): strong Lewis acids, sources of E(OTf) 3 and synthons for E I and E V cations. Chem Sci 2015; 6:6545-6555. [PMID: 30090272 PMCID: PMC6054056 DOI: 10.1039/c5sc02423d] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 08/03/2015] [Indexed: 11/22/2022] Open
Abstract
Triflate salts of trications [(bipy)2E]3+ ([6E][OTf]3) and [(tbbipy)2E]3+ ([6′E][OTf]3) (bipy = 2,2′-bipyridine, tbbipy = 4,4′-di-tbutyl-2,2′-bipyridine; E = P, As, Sb, Bi) have been synthesized and comprehensively characterized.
Triflate salts of trications [(bipy)2E]3+ ([6E][OTf]3) and [(tbbipy)2E]3+ ([6′E][OTf]3) (bipy = 2,2′-bipyridine, tbbipy = 4,4′-di-tbutyl-2,2′-bipyridine; E = P, As, Sb, Bi) have been synthesized and comprehensively characterized. The unique molecular and electronic structures of this new class of complexes involving pnictogen Lewis acids has been assessed in the solid, solution and gas phases to reveal systematic variations in metric parameters, ligand lability and charge concentration. While the Lewis acidity of E3+ has the trend E = Bi < Sb < As < P as determined by gas-phase calculations and 1H NMR spectroscopy, the Lewis acidity of [6E]3+ has the trend E = P < As < Sb < Bi according to gas-phase calculations. Derivatives of [6′E][OTf]3 (E = P, As) are latent sources of E(OTf)3 as demonstrated by their reactions with dmap, which give the corresponding derivatives of [(dmap)3E][OTf]3. The highly oxidizing nature of P(OTf)3 and As(OTf)3 is evidenced in reactions of [6′E][OTf]3 (E = P, As) with phosphines, which give EI-containing monocations [(R3P)2E]1+ and oxidatively coupled dications [R3PPR3]2+, illustrating new P–P and P–As bond forming strategies. Cations [6′E]3+ (E = P, As) are C–H bond activating agents that dehydrogenate 1,4-cyclohexadiene, with higher activity observed for E = P. Combinations of [6′E]3+ and tBu3P activate H2 and D2 under mild conditions, evidencing frustrated Lewis pair activity. Oxidation of [6′P][OTf]3 with SO2Cl2 gives [(tbbipy)2PCl2][OTf]3, containing a PV-trication, but there is no evidence of the analogous reaction with [6′As][OTf]3. The observations highlight new directions in the chemistry of highly charged cations and reveal a rich reactivity for p-block triflates E(OTf)3, which can be accessed through derivatives of [6E][OTf]3 and [6′E][OTf]3.
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Affiliation(s)
- Saurabh S Chitnis
- Department of Chemistry , University of Victoria , Victoria , British Columbia V8W 3V6 , Canada . ; ; Tel: +1 250 721 7150
| | - Alasdair P M Robertson
- Department of Chemistry , University of Victoria , Victoria , British Columbia V8W 3V6 , Canada . ; ; Tel: +1 250 721 7150
| | - Neil Burford
- Department of Chemistry , University of Victoria , Victoria , British Columbia V8W 3V6 , Canada . ; ; Tel: +1 250 721 7150
| | - Brian O Patrick
- Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z1 , Canada
| | - Robert McDonald
- Department of Chemistry , University of Alberta , Edmonton , Alberta T6G 2T2 , Canada
| | - Michael J Ferguson
- Department of Chemistry , University of Alberta , Edmonton , Alberta T6G 2T2 , Canada
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90
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Kwak J, Nghia NV, Lee J, Kim H, Park MH, Lee MH. Lewis acidity enhancement of triarylborane by appended phosphine oxide groups. Dalton Trans 2015; 44:4765-72. [PMID: 25668014 DOI: 10.1039/c5dt00042d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of mono-, di-, and tri-phosphine oxide substituted triarylboranes, Mes2BAr (1), MesBAr2 (2), and BAr3 (3) (Ar = 4-(Ph2PO)-2,6-Me2-C6H2) were prepared to investigate the effect of a phosphine oxide group (Ph2PO) on Lewis acidity enhancement of triarylboranes. The X-ray crystal structure of 3 revealed peripheral decoration of Ph2PO groups with a C3-axis perpendicular to the trigonal boron center. UV/Vis absorption and PL spectra indicated a significant contribution of π(Mes or phenylene) → pπ(B) charge transfer in the lower-energy electronic transition. The reduction potential measured by cyclic voltammetry showed apparent LUMO stabilization by introduction of phosphine oxide groups, the extent of which gradually increased with the increasing number of phosphine oxide groups. Lewis acidity enhancement was also supported by the gradual increase in fluoride ion affinity in the order 3 > 2 > 1. Theoretical calculations suggest that introduction of a Ph2PO group into a triarylborane significantly enhances the Lewis acidity of the boron center via an inductive electron-withdrawing effect and this effect is additive for multiple phosphine oxide groups.
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Affiliation(s)
- Jaewoo Kwak
- Department of Chemistry Education, Chungbuk National University, Cheongju 361-763, Republic of Korea.
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91
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Heiden ZM, Lathem AP. Establishing the Hydride Donor Abilities of Main Group Hydrides. Organometallics 2015. [DOI: 10.1021/om5011512] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Zachariah M. Heiden
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - A. Paige Lathem
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
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92
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Fan X, Zheng J, Li ZH, Wang H. Organoborane Catalyzed Regioselective 1,4-Hydroboration of Pyridines. J Am Chem Soc 2015; 137:4916-9. [DOI: 10.1021/jacs.5b03147] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Xiaoting Fan
- Collaborative Innovation
Center of Chemistry for Energy Material, Shanghai Key Laboratory of
Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Handan Road 220, Shanghai, 200433, China
| | - Junhao Zheng
- Collaborative Innovation
Center of Chemistry for Energy Material, Shanghai Key Laboratory of
Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Handan Road 220, Shanghai, 200433, China
| | - Zhen Hua Li
- Collaborative Innovation
Center of Chemistry for Energy Material, Shanghai Key Laboratory of
Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Handan Road 220, Shanghai, 200433, China
| | - Huadong Wang
- Collaborative Innovation
Center of Chemistry for Energy Material, Shanghai Key Laboratory of
Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Handan Road 220, Shanghai, 200433, China
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93
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Johnstone MD, Schwarze EK, Clever GH, Pfeffer FM. Inside Cover: Modular Synthesis of Linear Bis- and Tris-monodentate Fused [6]Polynorbornane-Based Ligands and their Assembly into Coordination Cages (Chem. Eur. J. 10/2015). Chemistry 2015. [DOI: 10.1002/chem.404242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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94
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Lawrence EJ, Blagg RJ, Hughes DL, Ashley AE, Wildgoose GG. A combined "electrochemical-frustrated lewis pair" approach to hydrogen activation: surface catalytic effects at platinum electrodes. Chemistry 2015; 21:900-6. [PMID: 25382457 PMCID: PMC4316182 DOI: 10.1002/chem.201404242] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Indexed: 11/11/2022]
Abstract
Herein, we extend our "combined electrochemical-frustrated Lewis pair" approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical-frustrated Lewis pair (FLP) system involving the B(C6 F5 )3 /[HB(C6 F5 )3 ](-) redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6 F5 )3 to B(C6 Cl5 )3 , the mechanism of electrochemical-FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [PtH] adatoms and transient [HB(C6 F5 )3 ](⋅) electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis.
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Affiliation(s)
- Elliot J Lawrence
- Energy Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
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95
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Zhang Z, Edkins RM, Nitsch J, Fucke K, Steffen A, Longobardi LE, Stephan DW, Lambert C, Marder TB. Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups. Chem Sci 2015; 6:308-321. [PMID: 28966759 PMCID: PMC5586071 DOI: 10.1039/c4sc02410a] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/01/2014] [Indexed: 12/21/2022] Open
Abstract
Three compounds with phenyl (1), 4-tert-butylphenyl (2) and 4-N,N-diphenylaminophenyl (3) groups attached to bis(fluoromesityl)boryl ((FMes)2B) through B-C bonds have been prepared. The restricted rotation about the B-C bonds of boron-bonded aryl rings in solution has been studied by variable-temperature 19F NMR spectroscopy, and through-space F-F coupling has been observed for 3 at low temperature. Steric congestion inhibits binding of 1 by Lewis bases DABCO and tBu3P and the activation of H2 in their presence. Photophysical and electrochemical studies have been carried out on 2, 3, and an analogue of 3 containing a bis(mesityl)boryl ((Mes)2B) group, namely 4. Both 2 and 3 show bright emission in nonpolar solvents and in the solid-state, very strong electron-accepting ability as measured by cyclic voltammetry, and good air-stability. In addition, 2 displayed unusually long-lived emission (τ = 2.47 s) in 2-MeTHF at 77 K. The much stronger acceptor strength of (FMes)2B than (Mes)2B leads to significantly red-shifted emission in solution and the solid state, stronger emission solvatochromism, and significantly lower reduction potentials. Theoretical calculations confirm that 2 and 3 tend to form highly twisted excited states with good conjugation between one FMes group and the boron atom, which correlate well with their blue-shifted solid-state emissions and low kr values in solution.
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Affiliation(s)
- Zuolun Zhang
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
| | - Robert M Edkins
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
| | - Jörn Nitsch
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
| | - Katharina Fucke
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
- School of Medicine , Pharmacy and Health , Durham University , University Boulevard , Stockton-on-Tees , TS17 6BH , UK
| | - Andreas Steffen
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
| | - Lauren E Longobardi
- Department of Chemistry , University of Toronto , 80 St. George St. , Toronto , Ontario M5S 3H6 , Canada
| | - Douglas W Stephan
- Department of Chemistry , University of Toronto , 80 St. George St. , Toronto , Ontario M5S 3H6 , Canada
| | - Christoph Lambert
- Institut für Organische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Todd B Marder
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany .
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96
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Hill PJ, Herrington TJ, Rees NH, White AJP, Ashley AE. H2 activation by a highly electron-deficient aralkylated organoborane. Dalton Trans 2015; 44:8984-92. [DOI: 10.1039/c5dt00821b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel, highly-electron deficient aralkylated homoleptic borane is able to activate dihydrogen wherein the ethereal solvent acts as Lewis base.
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Affiliation(s)
- Peter J. Hill
- Department of Chemistry
- Imperial College London
- London SW7 2AZ
- UK
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97
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Zhang Z, Edkins RM, Nitsch J, Fucke K, Eichhorn A, Steffen A, Wang Y, Marder TB. D-π-A triarylboron compounds with tunable push-pull character achieved by modification of both the donor and acceptor moieties. Chemistry 2014; 21:177-90. [PMID: 25413782 DOI: 10.1002/chem.201405621] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Indexed: 11/07/2022]
Abstract
The push-pull character of a series of donor-bithienyl-acceptor compounds has been tuned by adopting triphenylamine or 1,1,7,7-tetramethyljulolidine as a donor and B(2,6-Me2 -4-RC6 H2)2 (R=Me, C6 F5 or 3,5-(CF3)2 C6 H3) or B[2,4,6-(CF3 )3 C6 H2]2 as an acceptor. Ir-catalyzed C-H borylation was utilized in the derivatization of the boryl acceptors and the tetramethyljulolidine donor. The donor and acceptor strengths were evaluated by electrochemical and photophysical measurements. In solution, the compound with the strongest acceptor, B[2,4,6-(CF3)3 C6 H2]2 ((FMes)2 B), has strongly quenched emission, while all other compounds show efficient green to red (ΦF =0.80-1.00) or near-IR (NIR; ΦF =0.27-0.48) emission, depending on solvent. Notably, this study presents the first examples of efficient NIR emission from three-coordinate boron compounds. Efficient solid-state red emission was observed for some derivatives, and interesting aggregation-induced emission of the (FMes)2 B-containing compound was studied. Moreover, each compound showed a strong and clearly visible response to fluoride addition, with either a large emission-color change or turn-on fluorescence.
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Affiliation(s)
- Zuolun Zhang
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany)
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98
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Scott DJ, Fuchter MJ, Ashley AE. Nonmetal catalyzed hydrogenation of carbonyl compounds. J Am Chem Soc 2014; 136:15813-6. [PMID: 25333722 DOI: 10.1021/ja5088979] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solutions of the Lewis acid B(C6F5)3 in 1,4-dioxane are found to effectively catalyze the hydrogenation of a variety of ketones and aldehydes. These reactions, the first to allow entirely metal-free catalytic hydrogenation of carbonyl groups under relatively mild reaction conditions, are found to proceed via a "frustrated Lewis pair" mechanism in which the solvent, a weak Brønsted base yet moderately strong donor, plays a pivotal role.
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Affiliation(s)
- Daniel J Scott
- Department of Chemistry, Imperial College London , London SW7 2AZ, U.K
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99
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Synthetic, redox and coordination chemistry of bis(pentachlorophenyl)boryl ferrocene, FcB(C6Cl5)2. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2014.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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100
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Henthorn JT, Agapie T. Dioxygen Reactivity with a Ferrocene-Lewis Acid Pairing: Reduction to a Boron Peroxide in the Presence of Tris(pentafluorophenyl)borane. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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