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Kulsha AV, Ivashkevich OA, Lyakhov DA, Michels D. Strong Bases Design: Key Techniques and Stability Issues. Int J Mol Sci 2024; 25:8716. [PMID: 39201404 PMCID: PMC11354936 DOI: 10.3390/ijms25168716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Revised: 08/06/2024] [Accepted: 08/08/2024] [Indexed: 09/02/2024] Open
Abstract
Theoretical design of molecular superbases has been attracting researchers for more than twenty years. General approaches were developed to make the bases potentially stronger, but less attention was paid to the stability of the predicted structures. Hence, only a small fraction of the theoretical research has led to positive experimental results. Possible stability issues of extremely strong bases are extensively studied in this work using quantum chemical calculations on a high level of theory. Several step-by-step design examples are discussed in detail, and general recommendations are given to avoid the most common stability problems. New potentially stable structures are theoretically studied to demonstrate the future prospects of molecular superbases design.
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Affiliation(s)
- Andrey V. Kulsha
- Chemical Department, Belarusian State University, 14 Leningradskaya Str., 220006 Minsk, Belarus;
| | - Oleg A. Ivashkevich
- Research Institute for Physical Chemical Problems, Belarusian State University, 14 Leningradskaya Str., 220006 Minsk, Belarus
| | - Dmitry A. Lyakhov
- Computer, Electrical and Mathematical Science and Engineering Division, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia; (D.A.L.); (D.M.)
| | - Dominik Michels
- Computer, Electrical and Mathematical Science and Engineering Division, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia; (D.A.L.); (D.M.)
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2
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Kulsha AV, Ivashkevich OA. pH Indicators for Strong Molecular Bases: A Theoretical Approach. J Phys Chem A 2024; 128:4701-4704. [PMID: 38817074 DOI: 10.1021/acs.jpca.4c02567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
The transition points in hexamethylphosphoramide are theoretically studied for a series of acid-base indicators. Three new indicators with multiple transition points and deeply colored low-nucleophilic anions are designed. A general basicity scale is established for highly basic hexamethylphosphoramide solutions, expanding beyond the basicity of the strongest currently known molecular bases.
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Affiliation(s)
- Andrey V Kulsha
- Belarusian State University, 4 Nezavisimosti Avenue, Minsk 220030, Republic of Belarus
| | - Oleg A Ivashkevich
- Research Institute for Physical Chemical Problems of the Belarusian State Unversity, 14 Leningradskaya str., Minsk 220006, Republic of Belarus
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3
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Szlosek R, Niefanger AS, Balázs G, Seidl M, Timoshkin AY, Scheer M. Characterization of the Ligand Properties of Donor-stabilized Pnictogenyltrielanes. Chemistry 2024; 30:e202303603. [PMID: 38131435 DOI: 10.1002/chem.202303603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/15/2023] [Accepted: 12/21/2023] [Indexed: 12/23/2023]
Abstract
A general synthesis and the characterization of novel alkyl-substituted NHC-stabilized pnictogenylboranes NHC ⋅ BH2 ER2 (NHC=N-heterocyclic carbene, E=P, As; R2 =Me2 , Ph2 , t BuH, Cy2 , (SiMe3 )2 ) are reported. These compounds were reacted with Ni(CO)4 to the corresponding complexes of the type [(NHC ⋅ BH2 ER2 )Ni(CO)3 ] to determine their donor strength by Tolman Electronic Parameters (TEPs) and their steric demand as ligands compared to classical phosphines, superbasic phosphines and other commonly applied donor systems. The results show that the NHC-stabilized pnictogenyltrielanes can be considered as being highly basic, while their steric influence depends strongly on the organic residues as well as the donor attached to the {BH2 } moiety. Although weaker than commonly used superbasic phosphines, the donor strength of pnictogenyltrielanes in general can be classified as of similar strength as NHCs. The steric and electronic properties can easily be modified by alkyl substitution as evident from the TEP trends.
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Affiliation(s)
- Robert Szlosek
- Institut für Anorganische Chemie, Universität Regensburg, 93053, Regensburg, Germany
| | | | - Gábor Balázs
- Institut für Anorganische Chemie, Universität Regensburg, 93053, Regensburg, Germany
| | - Michael Seidl
- Institute of General and Theoretical Chemistry, Leopold-Franzens Universität Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | - Alexey Y Timoshkin
- Institute of Chemistry, Saint Petersburg State University, Universitetskaya emb. 7/9, 199034, St. Petersburg, Russia
| | - Manfred Scheer
- Institut für Anorganische Chemie, Universität Regensburg, 93053, Regensburg, Germany
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4
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Schulz J, Clauss R, Kazimir A, Holzknecht S, Hey-Hawkins E. On the Edge of the Known: Extremely Electron-Rich (Di)Carboranyl Phosphines. Angew Chem Int Ed Engl 2023; 62:e202218648. [PMID: 36573025 DOI: 10.1002/anie.202218648] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Indexed: 12/28/2022]
Abstract
The syntheses of the first B9-connected carboranylphosphines (B9-Phos) featuring two carboranyl moieties as well as access to B9-Phos ligands with bulky electron-donating substituents, previously deemed unattainable, is reported. The electrochemical properties of the B9-Phos ligands were investigated, revealing the ability of the mesityl derivatives to form stabilized phosphoniumyl radical cations. The B9-Phos ligands display an extremely electron-releasing character surpassing that of alkyl phosphines and commonly used N-heterocyclic carbenes. This is demonstrated by their very small Tolman electronic parameters (TEPs) as well as extremely low P-Se coupling constants. Cone angles and buried volumes attest to the high steric demand exerted by the (di)carboranyl phosphines. The dicarboranyl phosphine AuI complexes show superior catalytic performance in the hydroamination of alkynes compared to the monocarboranyl phosphine analogs.
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Affiliation(s)
- Jan Schulz
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103, Leipzig, Germany
| | - Reike Clauss
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103, Leipzig, Germany
| | - Aleksandr Kazimir
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103, Leipzig, Germany
| | - Sieglinde Holzknecht
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103, Leipzig, Germany
| | - Evamarie Hey-Hawkins
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103, Leipzig, Germany
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5
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Bedard J, Linford-Wood TG, Thompson BC, Werner-Zwanziger U, Marczenko KM, Musgrave RA, Chitnis SS. A Robust, Divalent, Phosphaza-bicyclo[2.2.2]octane Connector Provides Access to Cage-Dense Inorganic Polymers and Networks. J Am Chem Soc 2023; 145:7569-7579. [PMID: 36961918 DOI: 10.1021/jacs.3c00882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
While polymers containing chain or ring motifs in their backbone are ubiquitous, those containing well-defined molecular cages are very rare and essentially unknown for the inorganic elements. We report that a rigid and dinucleophilic cage (PNSiMe3)2(NMe)6, which is chemically robust and accessible on a multi-gram scale from commercial precursors, serves as a linear and divalent connector that forms cage-dense inorganic materials. Reaction of the cage with various ditopic P(III) dihalide comonomers proceeded via Me3SiCl elimination to give high molecular weight (30 000-70 000 g mol-1), solution-processable polymers that form free-standing films. The end groups of the polymers could be tuned to engender orthogonal reactivity and form block copolymers. Networked cage-dense materials could be accessed by using PCl3 as a tritopic P(III) linker. Detailed mechanistic studies implicate a stepwise polycondensation that proceeds via phosphino-phosphonium ion intermediates, prior to Me3SiCl loss. Thus, metathesis between the dinucleophilic cage and polyhalides represents a general strategy to making cage-dense polymers, setting the stage for systematically understanding the consequences of the three-dimensional microstructure on macroscopic material properties.
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Affiliation(s)
- Joseph Bedard
- Chemistry Department, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada
| | - Thomas G Linford-Wood
- Chemistry Department, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada
- Department of Chemistry, University of Bath, Bath BA2 7AY, U.K
| | - Benedict C Thompson
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Ulrike Werner-Zwanziger
- Chemistry Department, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada
| | - Katherine M Marczenko
- Chemistry Department, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada
| | - Rebecca A Musgrave
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Saurabh S Chitnis
- Chemistry Department, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada
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6
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Werra JA, Wurst K, Wilm LB, Löwe P, Röthel MB, Dielmann F. 1,2,5-Trimethylpyrrolyl Phosphines: A Class of Strongly Donating Arylphosphines. Organometallics 2023. [DOI: 10.1021/acs.organomet.3c00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
Affiliation(s)
- Janina A. Werra
- Institute of General Inorganic and Theoretical Chemistry, Universität Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
- Institute of Inorganic and Analytical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Klaus Wurst
- Institute of General Inorganic and Theoretical Chemistry, Universität Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Lukas B. Wilm
- Institute of Inorganic and Analytical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Pawel Löwe
- Institute of Inorganic and Analytical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Maike B. Röthel
- Institute of General Inorganic and Theoretical Chemistry, Universität Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Fabian Dielmann
- Institute of General Inorganic and Theoretical Chemistry, Universität Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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7
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Valadbeigi Y, Taheri R. Superbasicity of imines with bicyclo[5.1.0]octa-1,3,5,7-tetraene scaffold due to electron delocalization in the conjugated acids. COMPUT THEOR CHEM 2023. [DOI: 10.1016/j.comptc.2023.114076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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8
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Lops C, Pengo P, Pasquato L. Highly Efficient Darzens Reactions Mediated by Phosphazene Bases under Mild Conditions. ChemistryOpen 2022; 11:e202200179. [PMID: 36207800 PMCID: PMC9547082 DOI: 10.1002/open.202200179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/30/2022] [Indexed: 11/18/2022] Open
Abstract
The highly basic and poorly nucleophilic phosphazene base P1 -t-Bu promotes the Darzens condensation of α-halo esters with aromatic aldehydes affording α,β-epoxy esters in nearly quantitative yields under mild conditions and in short reaction times. The more basic P4 -t-Bu phosphazene was found useful with low reactivity aldehydes. These reactions can be performed in aprotic organic solvents of low polarity, thus minimizing the hydrolysis of α,β-epoxy esters which often accompanies the base-promoted Darzens condensations.
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Affiliation(s)
- Carmine Lops
- Department of Chemical and Pharmaceutical SciencesUniversity of TriesteVia L. Giorgieri 134127TriesteItaly
- Aptuit – an Evotec CompanyVia A. Fleming 437135VeronaItaly
| | - Paolo Pengo
- Department of Chemical and Pharmaceutical SciencesUniversity of TriesteVia L. Giorgieri 134127TriesteItaly
| | - Lucia Pasquato
- Department of Chemical and Pharmaceutical SciencesUniversity of TriesteVia L. Giorgieri 134127TriesteItaly
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9
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Modeling pKa of the Brønsted Bases as an Approach to the Gibbs Energy of the Proton in Acetonitrile. Int J Mol Sci 2022; 23:ijms231810576. [PMID: 36142490 PMCID: PMC9502073 DOI: 10.3390/ijms231810576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022] Open
Abstract
A simple but efficient computational approach to calculate pKa in acetonitrile for a set of phosphorus, nitrogen, and carbon bases was established. A linear function that describes relations between the calculated ΔG’a.sol(BH+) and pKa values was determined for each group of bases. The best model was obtained through the variations in the basis set, in the level of theory (density functionals or MP2), and in the continuum solvation model (IPCM, CPCM, or SMD). The combination of the IPCM/B3LYP/6-311+G(d,p) solvation approach with MP2/6-311+G(2df,p)//B3LYP/6-31G(d) gas-phase energies provided very good results for all three groups of bases with R2 values close to or above 0.99. Interestingly, the slopes and the intercepts of the obtained linear functions showed significant deviations from the theoretical values. We made a linear plot utilizing all the conducted calculations and all the structural variations and employed methods to prove the systematic nature of the intercept/slope dependence. The interpolation of the intercept to the ideal slope value enabled us to determine the Gibbs energy of the proton in acetonitrile, which amounted to −258.8 kcal mol−1. The obtained value was in excellent agreement with previously published results.
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10
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Zur J, Schmidt M, Feichtner K, Duari P, Löffler J, Scherpf T, Gessner VH. From Stable PH-Ylides to α-Carbanionic Phosphines as Ligands for Zwitterionic Catalysts. Angew Chem Int Ed Engl 2022; 61:e202203950. [PMID: 35644923 PMCID: PMC9401067 DOI: 10.1002/anie.202203950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Indexed: 11/08/2022]
Abstract
Although ylides are commonly used reagents in organic synthesis, the parent methylphosphine MePH2 only exists in its phosphine form in the condensed phase. Its ylide tautomer H3 P+ -CH2 - is considerably higher in energy. Here, we report on the formation of bis(sulfonyl)methyl-substituted phosphines of the type (RO2 S)2 C(H)-PR2, which form stable PH ylides under ambient conditions, amongst the first examples of an acyclic phosphine which only exists in its PH ylide form. Depending on the exact substitution pattern the phosphines form an equilibrium between the PH ylide and the phosphine form or exist as one of both extremes. These phosphines were found to be ideal starting systems for the facile formation of α-carbanionic phosphines. The carbanion-functionalization leads to a switch from electron-poor to highly electron-rich phosphines with strong donor abilities and high basicities. Thus, the phosphines readily react with different electrophiles exclusively at the phosphorus atom and not at the carbanionic center. Furthermore, the anionic nature of the phosphines allows the formation of zwitterionic complexes as demonstrated by the isolation of a gold(I) complex with a cationic metal center. The cationic gold center allows for catalytic activity in the hydroamination of alkyne without requiring a further activation step.
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Affiliation(s)
- Jana‐Alina Zur
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Michelle Schmidt
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Kai‐Stephan Feichtner
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Prakash Duari
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Julian Löffler
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Thorsten Scherpf
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
| | - Viktoria H. Gessner
- Chair of Inorganic Chemistry IIFaculty of Chemistry and BiochemistryRuhr-University BochumUniversitätsstrasse 15044780BochumGermany
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11
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Wei R, Ju S, Liu LL. Free Metallophosphines: Extremely Electron‐Rich Phosphorus Superbases That Are Electronically and Sterically Tunable**. Angew Chem Int Ed Engl 2022; 61:e202205618. [DOI: 10.1002/anie.202205618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Rui Wei
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
| | - Shaoying Ju
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
| | - Liu Leo Liu
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
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12
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Kulsha AV, Ragoyja EG, Ivashkevich OA. Strong Bases Design: Predicted Limits of Basicity. J Phys Chem A 2022; 126:3642-3652. [PMID: 35657384 DOI: 10.1021/acs.jpca.2c00521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Brønsted superbases have wide applications in organic chemistry due to their ability to activate C-H bonds. The strongest neutral bases to date are substituted aminophosphazenes developed in the late 1980s by Reinhard Schwesinger. Since then, much effort has been expended to create even stronger neutral bases. In this article, the reasons for the instability of very basic compounds are investigated by means of high-level quantum-chemical calculations. Theoretical basicity limits are suggested for solutions as well as for the gas phase. A record-breaking superbase most likely to be synthesizable and stable at ambient conditions is proposed. Hexamethylphosphoramide is considered a reliable ionizing solvent for superbases.
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Affiliation(s)
- Andrey V Kulsha
- Chemical Department, Belarusian State University, 4 Nezavisimosti Avenue, 220030 Minsk, Republic of Belarus
| | - Ekaterina G Ragoyja
- Chemical Department, Belarusian State University, 4 Nezavisimosti Avenue, 220030 Minsk, Republic of Belarus
| | - Oleg A Ivashkevich
- Laboratory for Chemistry of Condensed Systems, Research Institute for Physical Chemical Problems of the Belarusian State University, 14 Leningradskaya Street, 220006 Minsk, Republic of Belarus
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13
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Zur J, Schmidt M, Feichtner K, Duari P, Löffler J, Scherpf T, Gessner VH. From Stable PH‐Ylides to α‐Carbanionic Phosphines as Ligands for Zwitterionic Catalysts. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jana‐Alina Zur
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Michelle Schmidt
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Kai‐Stephan Feichtner
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Prakash Duari
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Julian Löffler
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Thorsten Scherpf
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
| | - Viktoria H. Gessner
- Chair of Inorganic Chemistry II Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44780 Bochum Germany
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14
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Wei R, Ju S, Liu LL. Free Metallophosphines: Extremely Electron‐Rich Phosphorus Superbases That Are Electronically and Sterically Tunable**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rui Wei
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
| | - Shaoying Ju
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
| | - Liu Leo Liu
- Department of Chemistry Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 China
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15
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16
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Buß F, Röthel MB, Werra JA, Rotering P, Wilm LFB, Daniliuc CG, Löwe P, Dielmann F. Tris(tetramethylguanidinyl)phosphine: The Simplest Non-ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand. Chemistry 2022; 28:e202104021. [PMID: 34793627 PMCID: PMC9300019 DOI: 10.1002/chem.202104021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Indexed: 12/13/2022]
Abstract
We report the synthesis and properties of the much sought-after tris(1,1,3,3-tetramethylguanidinyl) phosphine P(tmg)3 , a crystalline, superbasic phosphine accessible through a short and scalable procedure from the cheap and commercially available bulk chemicals 1,1,3,3-tetramethylguanidine, tris(dimethylamino)-phosphine and phosphorus trichloride. The new phosphine exhibits exceptional electron donor properties and readily forms transition metal complexes with gold(I), palladium(II) and rhodium(I) precursors. The formation of zwitterionic Lewis base adducts with carbon dioxide and sulfur dioxide was explored. In addition, the complete series of phosphine chalcogenides was prepared from the reaction of P(tmg)3 with N2 O and the elemental chalcogens.
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Affiliation(s)
- Florenz Buß
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstraße 28–3048149MünsterGermany
| | - Maike B. Röthel
- Institute of General, Inorganic and Theoretical ChemistryUniversity of Innsbruck, Center for Chemistry and BiomedicineInnrain 80–82A-6020InnsbruckAustria
| | - Janina A. Werra
- Institute of General, Inorganic and Theoretical ChemistryUniversity of Innsbruck, Center for Chemistry and BiomedicineInnrain 80–82A-6020InnsbruckAustria
| | - Philipp Rotering
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstraße 28–3048149MünsterGermany
| | - Lukas F. B. Wilm
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstraße 28–3048149MünsterGermany
| | - Constantin G. Daniliuc
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität MünsterCorrensstraße 4048149MünsterGermany
| | - Pawel Löwe
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstraße 28–3048149MünsterGermany
| | - Fabian Dielmann
- Institute of General, Inorganic and Theoretical ChemistryUniversity of Innsbruck, Center for Chemistry and BiomedicineInnrain 80–82A-6020InnsbruckAustria
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17
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Glen P. Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Douglas B. Grotjahn
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
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18
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021; 60:27253-27257. [PMID: 34729888 DOI: 10.1002/anie.202111588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/18/2021] [Indexed: 11/10/2022]
Abstract
A simple experimental procedure for scaling carbene Brønsted basicity is described. The results highlight the strong basicity of pyrazol-4-ylidenes, a type of mesoionic carbene, also named cyclic-bentallenes (CBA). They are more basic (pKaH >42.7 in acetonitrile) than the popular proazaphosphatrane Verkade bases, and even the Schwesinger phosphazene superbase P4 (t Bu). The basicity of these compounds can readily be tuned, and they are accessible in multigram quantities. These results open new avenues for carbon centered superbases.
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Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA.,Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Glen P Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Douglas B Grotjahn
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
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19
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Löffler J, Gauld RM, Feichtner KS, Rodstein I, Zur JA, Handelmann J, Schwarz C, Gessner VH. Ylide-Substituted Phosphines with a Cyclic Ylide-Backbone: Angle Dependence of the Donor Strength. Organometallics 2021; 40:2888-2900. [PMID: 34475611 PMCID: PMC8385760 DOI: 10.1021/acs.organomet.1c00349] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Indexed: 12/23/2022]
Abstract
Ylide-substituted phosphines (YPhos) have been shown to be highly electron-rich and efficient ligands in a variety of palladium catalyzed transformations. Here, the synthesis and characterization of novel YPhos ligands containing a cyclic backbone architecture are reported. The ligands are easily synthesized from a cyclic phosphonium salt and the chlorophosphines Cy2PCl (L1) and Cy(FluMe)PCl (L2, with FluMe = 9-methylfluorenyl) and were characterized in both solution and solid states. The smaller PCy2-substituted ligand, L1, readily formed the biscoordinate L1 2 Pd species when treated with Pd2(dba)3 and showed no activity in palladium-catalyzed amination reactions even when applied as defined palladium(II) η3-allyl, t-Bu-indenyl, or cinnamyl precursors. Bulkier fluorenyl-substituted ligand L2 similarly was inactive, despite its ability to form the stable monophosphine complex L2·Pd(dba). Assessment of the electronic properties by experimental and computational methods revealed that L1 and L2 are considerably less electron-rich than previously synthesized YPhos ligands. This was shown to be the result of the small P-C-S bond angle, which is sterically enforced due to the cyclic nature of the backbone. Density functional theory calculations revealed that the small angle results in an increased s-character of the lone pair at the ylidic carbon atom and leads to a polarization of the C-P bond toward the carbon atom, thus decreasing the electron density at the phosphorus atom. The results demonstrate the tunability of the donor strength of YPhos ligands by modification of the ligand backbone beyond simple changes of the substitution pattern and are thus important for future ligand design, with a careful balance of many factors to be considered to achieve catalytic activity.
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Affiliation(s)
- Julian Löffler
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Richard M. Gauld
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Kai-Stephan Feichtner
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Ilja Rodstein
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Jana-Alina Zur
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Jens Handelmann
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Christopher Schwarz
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Viktoria H. Gessner
- Chair
of Inorganic Chemistry II, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
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20
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Vazdar K, Margetić D, Kovačević B, Sundermeyer J, Leito I, Jahn U. Design of Novel Uncharged Organic Superbases: Merging Basicity and Functionality. Acc Chem Res 2021; 54:3108-3123. [PMID: 34308625 DOI: 10.1021/acs.accounts.1c00297] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
ConspectusOne of the constant challenges of synthetic chemistry is the molecular design and synthesis of nonionic, metal-free superbases as chemically stable neutral organic compounds of moderate molecular weight, intrinsically high thermodynamic basicity, adaptable kinetic basicity, and weak or tunable nucleophilicity at their nitrogen, phosphorus, or carbon basicity centers. Such superbases can catalyze numerous reactions, ranging from C-C bond formation to cycloadditions and polymerization, to name just a few. Additional benefits of organic superbases, as opposed to their inorganic counterparts, are their solubility in organic reaction media, mild reaction conditions, and higher selectivity. Approaching such superbasic compounds remains a continuous challenge. However, recent advances in synthetic methodology and theoretical understanding have resulted in new design principles and synthetic strategies toward superbases. Our computational contributions have demonstrated that the gas-phase basicity region of 350 kcal mol-1 and even beyond is easily reachable by organosuperbases. However, despite record-high basicities, the physical limitations of many of these compounds become quickly evident. The typically large molecular weight of these molecules and their sensitivity to ordinary reaction conditions prevent them from being practical, even though their preparation is often not too difficult. Thus, obviously structural limitations with respect to molecular weight and structural complexity must be imposed on the design of new synthetically useful organic superbases, but strategies for increasing their basicity remain important.The contemporary design of novel organic superbases is illustrated by phosphazenyl phosphanes displaying gas-phase basicities (GB) above 300 kcal mol-1 but having molecular weights well below 1000 g·mol-1. This approach is based on a reconsideration of phosphorus(III) compounds, which goes along with increasing their stability in solution. Another example is the preparation of carbodiphosphoranes incorporating pyrrolidine, tetramethylguanidine, or hexamethylphosphazene as a substituent. With gas-phase proton affinities of up to 300 kcal mol-1, they are among the top nonionic carbon bases on the basicity scale. Remarkably, the high basicity of these compounds is achieved at molecular weights of around 600 g·mol-1. Another approach to achieving high basicity through the cooperative effect of multiple intramolecular hydrogen bonding, which increases the stabilization of conjugate acids, has recently been confirmed.This Account focuses on our efforts to produce superbasic molecules that embody many desirable traits, but other groups' approaches will also be discussed. We reveal the crucial structural features of superbases and place them on known basicity scales. We discuss the emerging potential and current limits of their application and give a general outlook into the future.
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Affiliation(s)
- Katarina Vazdar
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, v.v.i. Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | | | | | - Jörg Sundermeyer
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Ullrich Jahn
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, v.v.i. Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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21
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Weitkamp RF, Neumann B, Stammler H, Hoge B. Phosphorus-Containing Superbases: Recent Progress in the Chemistry of Electron-Abundant Phosphines and Phosphazenes. Chemistry 2021; 27:10807-10825. [PMID: 34032319 PMCID: PMC8362139 DOI: 10.1002/chem.202101065] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Indexed: 01/11/2023]
Abstract
The renaissance of Brønsted superbases is primarily based on their pronounced capacity for a large variety of chemical transformations under mild reaction conditions. Four major set screws are available for the selective tuning of the basicity: the nature of the basic center (N, P, …), the degree of electron donation by substituents to the central atom, the possibility of charge delocalization, and the energy gain by hydrogen bonding. Within the past decades, a plethora of neutral electron-rich phosphine and phosphazene bases have appeared in the literature. Their outstanding properties and advantages over inorganic or charged bases have now made them indispensable as auxiliary bases in deprotonation processes. Herein, an update of the chemistry of basic phosphines and phosphazenes is given. In addition, due to widespread interest, their use in catalysis or as ligands in coordination chemistry is highlighted.
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Affiliation(s)
- Robin F. Weitkamp
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Beate Neumann
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Berthold Hoge
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
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22
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Puleo TR, Sujansky SJ, Wright SE, Bandar JS. Organic Superbases in Recent Synthetic Methodology Research. Chemistry 2021; 27:4216-4229. [DOI: 10.1002/chem.202003580] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Indexed: 12/23/2022]
Affiliation(s)
- Thomas R. Puleo
- Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA
| | - Stephen J. Sujansky
- Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA
| | - Shawn E. Wright
- Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA
| | - Jeffrey S. Bandar
- Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA
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23
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Richard NA, Khor CK, Hetherington SM, Mills SL, Decken A, Dyker CA. Iminophosphorano-Substituted Bispyridinylidenes: Redox Potentials and Substituent Constants from Tolman Electronic Parameters. Chemistry 2020; 26:17371-17375. [PMID: 33022780 DOI: 10.1002/chem.202004153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 09/26/2020] [Indexed: 12/21/2022]
Abstract
Bispyridinylidenes (BPYs) have emerged as an important class of neutral organic electron donors, with redox potentials that vary widely with choice of substituent. Methods to predict the effect of substitution on the redox potential are therefore highly desirable. Here we show that the redox potential of BPYs featuring iminophosphorano substituents (R3 P=N-), which represent the most reducing class of BPYs, can be predicted based on the well-known Tolman electronic parameter (TEP) for the respective phosphine fragment (R3 P). Moreover, building on earlier work relating redox potentials to Hammett-type substituent constants, it is now possible to quantitatively predict σp + values for iminophosphorano substituents from TEP values. These results provide a path for precisely tailoring redox potentials of iminophosphorano-substituted BPYs, but also give quantitative descriptors for how these highly versatile iminophosphorano substituents can impact the properties of any molecular scaffold.
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Affiliation(s)
- Nicholas A Richard
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Chun Keat Khor
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Sydney M Hetherington
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Scott L Mills
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Andreas Decken
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - C Adam Dyker
- Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
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24
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Valadbeigi Y. Effects of intramolecular hydrogen bond and electron delocalization on the basicity of proton sponges and superbases with benzene, pyridine, pyrazine and pyrimidine scaffolds. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112947] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Siewert JE, Schumann A, Fischer M, Schmidt C, Taeufer T, Hering-Junghans C. Terphenyl(bisamino)phosphines: electron-rich ligands for gold-catalysis. Dalton Trans 2020; 49:12354-12364. [PMID: 32845265 DOI: 10.1039/d0dt02435j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Terphenyl(bisamino)phosphines have been identified as effective ligands in cationic gold(i) complexes for the hydroamination of acetylenes. These systems are related to Buchwald phosphines and their steric properties have been evaluated. Effective hydroamination was noted even at low catalyst loadings and a series of cationic gold(i) complexes has been structurally characterized clearly indicating stabilizing effects through gold-arene interactions.
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Affiliation(s)
- Jan-Erik Siewert
- Leibniz-Institut für Katalyse e.V. Rostock Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
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26
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Saadat K, Shiri A, Kovačević B. Step Forward to Stronger Neutral Organic Superbases: Fused Troponimines. J Org Chem 2020; 85:11375-11381. [DOI: 10.1021/acs.joc.0c01466] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kayvan Saadat
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
| | - Ali Shiri
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
| | - Borislav Kovačević
- Group for Computational Life Science, Division of Chemistry, Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb, Croatia
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27
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Sarbajna A, Swamy VSVSN, Gessner VH. Phosphorus-ylides: powerful substituents for the stabilization of reactive main group compounds. Chem Sci 2020; 12:2016-2024. [PMID: 34163963 PMCID: PMC8179322 DOI: 10.1039/d0sc03278f] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phosphorus ylides are 1,2-dipolar compounds with a negative charge on the carbon atom. This charge is stabilized by the neighbouring onium moiety, but can also be shifted towards other substituents thus making ylides strong π donor ligands and hence ideal substituents to stabilize reactive compounds such as cations and low-valent main group species. Furthermore, the donor strength and the steric properties can easily be tuned to meet different requirements for stabilizing reactive compounds and for tailoring the properties and reactivities of the main group element. Although the use of ylide substituents in main group chemistry is still in its infancy, the first examples of isolated compounds impressively demonstrate the potential of these ligands. This review summarizes the most important discoveries also in comparison to other substituents, thus outlining avenues for future research directions.
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Affiliation(s)
- Abir Sarbajna
- Faculty of Chemistry and Biochemistry, Chair of Inorganic Chemistry II, Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
| | - V S V S N Swamy
- Faculty of Chemistry and Biochemistry, Chair of Inorganic Chemistry II, Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
| | - Viktoria H Gessner
- Faculty of Chemistry and Biochemistry, Chair of Inorganic Chemistry II, Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany
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28
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Effective Control of the Electron‐donating Ability of Phosphines by using Phosphazenyl and Phosphoniumylidyl Substituents. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.202000028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Kögel JF, Ullrich S, Kovačević B, Wagner S, Sundermeyer J. Mono‐Phosphazenyl Phosphines (R
2
N)
3
P=N–P(NR
2
)
2
– Strong P‐Bases, P‐Donors, and P‐Nucleophiles for the Construction of Chelates. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.202000108] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Julius F. Kögel
- Fachbereich Chemie Philipps‐Universität Marburg Hans‐Meerwein‐Straße 35032 Marburg Germany
| | - Sebastian Ullrich
- Fachbereich Chemie Philipps‐Universität Marburg Hans‐Meerwein‐Straße 35032 Marburg Germany
| | - Borislav Kovačević
- Group for Computational Life Sciences Rudjer Bošković Institute Bijenička c. 54 10000 Zagreb Croatia
| | - Sebastian Wagner
- Fachbereich Chemie Philipps‐Universität Marburg Hans‐Meerwein‐Straße 35032 Marburg Germany
| | - Jörg Sundermeyer
- Fachbereich Chemie Philipps‐Universität Marburg Hans‐Meerwein‐Straße 35032 Marburg Germany
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30
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Tappen J, Rodstein I, McGuire K, Großjohann A, Löffler J, Scherpf T, Gessner VH. Palladium Complexes Based on Ylide-Functionalized Phosphines (YPhos): Broadly Applicable High-Performance Precatalysts for the Amination of Aryl Halides at Room Temperature. Chemistry 2020; 26:4281-4288. [PMID: 31971642 PMCID: PMC7186839 DOI: 10.1002/chem.201905535] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 01/20/2020] [Indexed: 12/13/2022]
Abstract
Palladium allyl, cinnamyl, and indenyl complexes with the ylide-substituted phosphines Cy3 P+ -C- (R)PCy2 (with R=Me (L1) or Ph (L2)) and Cy3 P+ -C- (Me)PtBu2 (L3) were prepared and applied as defined precatalysts in C-N coupling reactions. The complexes are highly active in the amination of 4-chlorotoluene with a series of different amines. Higher yields were observed with the precatalysts in comparison to the in situ generated catalysts. Changes in the ligand structures allowed for improved selectivities by shutting down β-hydride elimination or diarylation reactions. Particularly, the complexes based on L2 (joYPhos) revealed to be universal precatalysts for various amines and aryl halides. Full conversions to the desired products are reached mostly within 1 h reaction time at room temperature, thus making L2 to one of the most efficient ligands in C-N coupling reactions. The applicability of the catalysts was demonstrated for aryl chlorides, bromides and iodides together with primary and secondary aryl and alkyl amines, including gram-scale applications also with low catalyst loadings of down to 0.05 mol %. Kinetic studies further demonstrated the outstanding activity of the precatalysts with TOF over 10.000 h-1 .
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Affiliation(s)
- Jens Tappen
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Ilja Rodstein
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Katie McGuire
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Angela Großjohann
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Julian Löffler
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Thorsten Scherpf
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
| | - Viktoria H. Gessner
- Faculty of Chemistry and BiochemistryChair of Inorganic Chemistry IIRuhr University BochumUniversitätsstr. 15044801BochumGermany
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31
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Rotering P, Wilm LFB, Werra JA, Dielmann F. Pyridinylidenaminophosphines: Facile Access to Highly Electron-Rich Phosphines. Chemistry 2020; 26:406-411. [PMID: 31688978 PMCID: PMC6972615 DOI: 10.1002/chem.201904621] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Indexed: 11/10/2022]
Abstract
Electron-rich tertiary phosphines are valuable species in chemical synthesis. However, their broad application as ligands in catalysis and reagents in stoichiometric reactions is often limited by their costly synthesis. Herein, we report the synthesis and properties of a series of phosphines with 1-alkylpyridin-4-ylidenamino and 1-alkylpyridin-2-ylidenamino substituents that are accessible in a very short and scalable route starting from commercially available aminopyridines and chlorophosphines. The determination of the Tolman electronic parameter (TEP) value reveals that the electron donor ability can be tuned by the substituent pattern at the aminopyridine backbone and it can exceed that of common alkylphosphines and N-heterocyclic carbenes. The potential of the new phosphines as strong nucleophiles in phosphine-mediated transformations is demonstrated by the formation of Lewis base adducts with CO2 and CS2 . In addition, the coordination chemistry of the new phosphines towards CuI , AuI , and PdII metal centers has been explored, and a convenient procedure to introduce the most basic phosphine into metal complexes starting from air-stable phosphonium salt is described.
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Affiliation(s)
- Philipp Rotering
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstrasse 3048149MünsterGermany
| | - Lukas F. B. Wilm
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstrasse 3048149MünsterGermany
| | - Janina A. Werra
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstrasse 3048149MünsterGermany
| | - Fabian Dielmann
- Institut für Anorganische und Analytische ChemieWestfälische Wilhelms-Universität MünsterCorrensstrasse 3048149MünsterGermany
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32
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Ullrich S, Kovačević B, Koch B, Harms K, Sundermeyer J. Design of non-ionic carbon superbases: second generation carbodiphosphoranes. Chem Sci 2019; 10:9483-9492. [PMID: 32055322 PMCID: PMC6993619 DOI: 10.1039/c9sc03565f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/15/2019] [Indexed: 12/31/2022] Open
Abstract
A new generation of carbodiphosphoranes (CDPs), incorporating pyrrolidine, tetramethylguanidine, or tris(dimethylamino)phosphazene as substituents is introduced as the most powerful class of non-ionic carbon superbases on the basicity scale to date. The synthetic approach as well as NMR spectroscopic and structural characteristics in the free and protonated form are described. Investigation of basicity in solution and in the gas phase by experimental and theoretical means provides the to our knowledge first reported pK BH + values for CDPs in the literature and suggest them as upper tier superbases.
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Affiliation(s)
- Sebastian Ullrich
- Fachbereich Chemie , Philipps-University Marburg , Hans-Meerwein-Straße , 35032 Marburg , Germany .
| | - Borislav Kovačević
- The Group for Computational Life Sciences , Rudjer Bošković Institute , Bijenička c. 54 , HR-10000 Zagreb , Croatia
| | - Björn Koch
- Fachbereich Chemie , Philipps-University Marburg , Hans-Meerwein-Straße , 35032 Marburg , Germany .
| | - Klaus Harms
- Fachbereich Chemie , Philipps-University Marburg , Hans-Meerwein-Straße , 35032 Marburg , Germany .
| | - Jörg Sundermeyer
- Fachbereich Chemie , Philipps-University Marburg , Hans-Meerwein-Straße , 35032 Marburg , Germany .
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33
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Ullrich S, Barić D, Xie X, Kovačević B, Sundermeyer J. Basicity Enhancement by Multiple Intramolecular Hydrogen Bonding in Organic Superbase N,N′,N″,N‴-Tetrakis(3-(dimethylamino)propyl)triaminophosphazene. Org Lett 2019; 21:9142-9146. [DOI: 10.1021/acs.orglett.9b03521] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sebastian Ullrich
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
| | - Danijela Barić
- The Group for Computational Life Sciences, Ruđer Bošković Institute, Bijenička c. 54, HR-10000 Zagreb, Croatia
| | - Xiulan Xie
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
| | - Borislav Kovačević
- The Group for Computational Life Sciences, Ruđer Bošković Institute, Bijenička c. 54, HR-10000 Zagreb, Croatia
| | - Jörg Sundermeyer
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
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Barić D. Utilizing the Azaazulene Scaffolds in the Design of New Organic Superbases. ACS OMEGA 2019; 4:15197-15207. [PMID: 31552365 PMCID: PMC6751732 DOI: 10.1021/acsomega.9b02087] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
New neutral organic superbases with 1-azaazulene(s) as a molecular backbone are computationally designed, employing two basic substituents: dimethylaminocyclopropen-imines (CPI) and dimethylaminocyclopropeniminophosphazenes (CPI-P). Their proton affinities, gas basicities, and pK a values in acetonitrile are obtained using density functional theory. Azaazulenes substituted with CPI have a computed PA in the gas phase ranging between 272.9 and 306.8 kcal mol-1, with pK a values in acetonitrile between 28.8 and 36 units. The substitution with the CPI-P group resulted in even stronger superbases, with a PA from 296.5 to 335.2 kcal mol-1 and corresponding pK a values from 33.9 to 50 units. This exceptionally strong thermodynamic basicity is accompanied by very high kinetic basicity as well; contrary to typical proton sponges, the release of a proton from the conjugate superbase does not demand high activation energy. Because synthetic routes for both substituents and azaazulenes are already known, newly designed superbases represent suitable targets for synthesis and application.
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