1
|
Hannibal VD, Greb L. Tetra-Amido Macrocyclic Ligand (TAML) at Silicon(IV): A Structurally Constrained, Water-Soluble Silicon Lewis Superacid. J Am Chem Soc 2024; 146:25727-25737. [PMID: 39223943 DOI: 10.1021/jacs.4c08015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Tetracoordinate silicon species are typically tetrahedral, weak Lewis acids, and often sensitive to moisture. In this study, we present a tetra-amido macrocyclic ligand (TAML)-substituted Si(IV), isolated as its bis(pyridine) adduct. Due to structural constraint toward anti van't-Hof/Le Bel geometry, this compound exhibits Lewis superacidity and effectively catalyzes the hydroboration of pyridine. Kinetic and computational analyses of the catalytic cycle reveal that TAML-Si(IV) acts as a hydride transfer agent, and the hydrido silicate key intermediate is isolated. Notably, the Lewis acid is highly soluble (5 g/L) and long-term stable in water. Unlike previously described silicon-H2O adducts, the bound water becomes substantially acidified, reaching the Bro̷nsted superacidity range. A comparison of water affinity versus pKa lowering confirms our previous theory of the strength and the effect of Lewis acids. Overall, the compound's unlimited water compatibility and its mechanistically understood catalytic efficiency mark significant progress in applying structural constraint strategies for p-block element-based catalysis, while the acidification touches critical aspects of zeolite and silica surface chemistry.
Collapse
Affiliation(s)
- Valentin D Hannibal
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, Heidelberg 69120, Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, Heidelberg 69120, Germany
| |
Collapse
|
2
|
Domenianni LI, Bauer M, Schmidt-Räntsch T, Lindner J, Schneider S, Vöhringer P. Photoinduced Metallonitrene Formation by N 2 Elimination from Azide Diradical Ligands. Angew Chem Int Ed Engl 2023; 62:e202309618. [PMID: 37549374 DOI: 10.1002/anie.202309618] [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: 07/07/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
Transition-metal nitrides/nitrenes are highly promising reagents for catalytic nitrogen-atom-transfer reactivity. They are typically prepared in situ upon optically induced N2 elimination from azido precursors. A full exploitation of their catalytic potential, however, requires in-depth knowledge of the primary photo-induced processes and the structural/electronic factors mediating the N2 loss with birth of the terminal metal-nitrogen core. Using femtosecond infrared spectroscopy, we elucidate here the primary molecular-level mechanisms responsible for the formation of a unique platinum(II) nitrene with a triplet ground state from a closed-shell platinum(II) azide precursor. The spectroscopic data in combination with quantum-chemical calculations provide compelling evidence that product formation requires the initial occupation of a singlet excited state with an anionic azide diradical ligand that is bound to a low-spin d8 -configured PtII ion. Subsequent intersystem crossing generates the Pt-bound triplet azide diradical, which smoothly evolves into the triplet nitrene via N2 loss in a near barrierless adiabatic dissociation. Our data highlight the importance of the productive, N2 -releasing state possessing azide ππ* character as a design principle for accessing efficient N-atom-transfer catalysts.
Collapse
Affiliation(s)
- Luis I Domenianni
- Clausius-Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115, Bonn, Germany
| | - Markus Bauer
- Clausius-Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115, Bonn, Germany
| | - Till Schmidt-Räntsch
- Georg-August-Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Jörg Lindner
- Clausius-Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115, Bonn, Germany
| | - Sven Schneider
- Georg-August-Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Peter Vöhringer
- Clausius-Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115, Bonn, Germany
| |
Collapse
|
3
|
Mitchell BS, Chirila A, Kephart JA, Boggiano AC, Krajewski SM, Rogers D, Kaminsky W, Velian A. Metal-Support Interactions in Molecular Single-Site Cluster Catalysts. J Am Chem Soc 2022; 144:18459-18469. [PMID: 36170652 DOI: 10.1021/jacs.2c07033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study provides atomistic insights into the interface between a single-site catalyst and a transition metal chalcogenide support and reveals that peak catalytic activity occurs when edge/support redox cooperativity is maximized. A molecular platform MCo6Se8(PEt3)4(L)2 (1-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (Co6Se8) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal 1-M clusters display remarkable catalytic activity for coupling tosyl azide and tert-butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series. Structural, electronic, and magnetic characterization of the clusters was performed using single crystal X-ray diffraction, 1H and 31P nuclear magnetic resonance spectroscopy, electronic absorption spectroscopy, cyclic voltammetry, and computational methods. Distinct metal/support redox regimes can be accessed in 1-M based on the energy of the edge metal's frontier orbitals with respect to those of the cluster support. As the degree of electronic interaction between the edge and the support increases, a cooperative regime is reached wherein the support can deliver electrons to the catalytic site, increasing the reactivity of key metal-nitrenoid intermediates.
Collapse
Affiliation(s)
- Benjamin S Mitchell
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Andrei Chirila
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Jonathan A Kephart
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Andrew C Boggiano
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Sebastian M Krajewski
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Dylan Rogers
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Werner Kaminsky
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Alexandra Velian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
4
|
Aziridination Reactivity of a Manganese(II) Complex with a Bulky Chelating Bis(Alkoxide) Ligand. Molecules 2022; 27:molecules27185751. [PMID: 36144492 PMCID: PMC9505844 DOI: 10.3390/molecules27185751] [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: 08/15/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
Treatment of Mn(N(SiMe3)2)2(THF)2 with bulky chelating bis(alkoxide) ligand [1,1′:4′,1′′-terphenyl]-2,2′′-diylbis(diphenylmethanol) (H2[O-terphenyl-O]Ph) formed a seesaw manganese(II) complex Mn[O-terphenyl-O]Ph(THF)2, characterized by structural, spectroscopic, magnetic, and analytical methods. The reactivity of Mn[O-terphenyl-O]Ph(THF)2 with various nitrene precursors was investigated. No reaction was observed between Mn[O-terphenyl-O]Ph(THF)2 and aryl azides. In contrast, the treatment of Mn[O-terphenyl-O]Ph(THF)2 with iminoiodinane PhINTs (Ts = p-toluenesulfonyl) was consistent with the formation of a metal-nitrene complex. In the presence of styrene, the reaction led to the formation of aziridine. Combining varying ratios of styrene and PhINTs in different solvents with 10 mol% of Mn[O-terphenyl-O]Ph(THF)2 at room temperature produced 2-phenylaziridine in up to a 79% yield. Exploration of the reactivity of Mn[O-terphenyl-O]Ph(THF)2 with various olefins revealed (1) moderate aziridination yields for p-substituted styrenes, irrespective of the electronic nature of the substituent; (2) moderate yield for 1,1′-disubstituted α-methylstyrene; (3) no aziridination for aliphatic α-olefins; (4) complex product mixtures for the β-substituted styrenes. DFT calculations suggest that iminoiodinane is oxidatively added upon binding to Mn, and the resulting formal imido intermediate has a high-spin Mn(III) center antiferromagnetically coupled to an imidyl radical. This imidyl radical reacts with styrene to form a sextet intermediate that readily reductively eliminates the formation of a sextet Mn(II) aziridine complex.
Collapse
|
5
|
Schmidt‐Räntsch T, Verplancke H, Lienert JN, Demeshko S, Otte M, Van Trieste GP, Reid KA, Reibenspies JH, Powers DC, Holthausen MC, Schneider S. Nitrogen Atom Transfer Catalysis by Metallonitrene C-H Insertion: Photocatalytic Amidation of Aldehydes. Angew Chem Int Ed Engl 2022; 61:e202115626. [PMID: 34905281 PMCID: PMC9305406 DOI: 10.1002/anie.202115626] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Indexed: 11/18/2022]
Abstract
C-H amination and amidation by catalytic nitrene transfer are well-established and typically proceed via electrophilic attack of nitrenoid intermediates. In contrast, the insertion of (formal) terminal nitride ligands into C-H bonds is much less developed and catalytic nitrogen atom transfer remains unknown. We here report the synthesis of a formal terminal nitride complex of palladium. Photocrystallographic, magnetic, and computational characterization support the assignment as an authentic metallonitrene (Pd-N) with a diradical nitrogen ligand that is singly bonded to PdII . Despite the subvalent nitrene character, selective C-H insertion with aldehydes follows nucleophilic selectivity. Transamidation of the benzamide product is enabled by reaction with N3 SiMe3 . Based on these results, a photocatalytic protocol for aldehyde C-H trimethylsilylamidation was developed that exhibits inverted, nucleophilic selectivity as compared to typical nitrene transfer catalysis. This first example of catalytic C-H nitrogen atom transfer offers facile access to primary amides after deprotection.
Collapse
Affiliation(s)
- Till Schmidt‐Räntsch
- Institut für Anorganische ChemieUniversität GöttingenTammannstraße 437077GöttingenGermany
| | - Hendrik Verplancke
- Institut für Anorganische und Analytische ChemieGoethe-UniversitätMax-von-Laue-Straße 760438Frankfurt am MainGermany
| | - Jonas N. Lienert
- Institut für Anorganische und Analytische ChemieGoethe-UniversitätMax-von-Laue-Straße 760438Frankfurt am MainGermany
| | - Serhiy Demeshko
- Institut für Anorganische ChemieUniversität GöttingenTammannstraße 437077GöttingenGermany
| | - Matthias Otte
- Institut für Anorganische ChemieUniversität GöttingenTammannstraße 437077GöttingenGermany
| | | | - Kaleb A. Reid
- Department of ChemistryTexas A&M University3255 TAMUCollege StationTX 77843USA
| | | | - David C. Powers
- Department of ChemistryTexas A&M University3255 TAMUCollege StationTX 77843USA
| | - Max C. Holthausen
- Institut für Anorganische und Analytische ChemieGoethe-UniversitätMax-von-Laue-Straße 760438Frankfurt am MainGermany
| | - Sven Schneider
- Institut für Anorganische ChemieUniversität GöttingenTammannstraße 437077GöttingenGermany
| |
Collapse
|
6
|
Schmidt‐Räntsch T, Verplancke H, Lienert JN, Demeshko S, Otte M, Van Trieste GP, Reid KA, Reibenspies JH, Powers DC, Holthausen MC, Schneider S. Nitrogen Atom Transfer Catalysis by Metallonitrene C−H Insertion: Photocatalytic Amidation of Aldehydes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Till Schmidt‐Räntsch
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Hendrik Verplancke
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Jonas N. Lienert
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Serhiy Demeshko
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Matthias Otte
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | | | - Kaleb A. Reid
- Department of Chemistry Texas A&M University 3255 TAMU College Station TX 77843 USA
| | | | - David C. Powers
- Department of Chemistry Texas A&M University 3255 TAMU College Station TX 77843 USA
| | - Max C. Holthausen
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Sven Schneider
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| |
Collapse
|
7
|
Van Trieste GP, Reid KA, Hicks MH, Das A, Figgins MT, Bhuvanesh N, Ozarowski A, Telser J, Powers DC. Nitrene Photochemistry of Manganese
N
‐Haloamides**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Kaleb A. Reid
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - Madeline H. Hicks
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - Anuvab Das
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - Matthew T. Figgins
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - Nattamai Bhuvanesh
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory Florida State University Tallahassee FL 32310 USA
| | - Joshua Telser
- Department of Biological, Physical and Chemical Sciences Roosevelt University Chicago IL 60605 USA
| | - David C. Powers
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| |
Collapse
|
8
|
Van Trieste GP, Reid KA, Hicks MH, Das A, Figgins MT, Bhuvanesh N, Ozarowski A, Telser J, Powers DC. Nitrene Photochemistry of Manganese N-Haloamides*. Angew Chem Int Ed Engl 2021; 60:26647-26655. [PMID: 34662473 DOI: 10.1002/anie.202108304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Indexed: 11/06/2022]
Abstract
Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C-H amination and olefin aziridination catalysis. The reactivity of the transient high-valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of MnIII N-haloamide complexes. The S=2 N-haloamide complexes are characterized by 1 H NMR, UV-vis, IR, high-frequency and -field EPR (HFEPR) spectroscopies, and single-crystal X-ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C-H bonds, such as the α-C-H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low-temperature spectroscopy and analysis of kinetic isotope effects for C-H amination indicate halogen-dependent photoreactivity: Photolysis of N-chloroamides proceeds via initial cleavage of the Mn-N bond to generate MnII and amidyl radical intermediates; in contrast, photolysis of N-iodoamides proceeds via N-I cleavage to generate a MnIV nitrenoid (i.e., {MnNR}7 species). These results establish N-haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group-transfer catalysis.
Collapse
Affiliation(s)
| | - Kaleb A Reid
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Madeline H Hicks
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Anuvab Das
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Matthew T Figgins
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Nattamai Bhuvanesh
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Joshua Telser
- Department of Biological, Physical and Chemical Sciences, Roosevelt University, Chicago, IL, 60605, USA
| | - David C Powers
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| |
Collapse
|
9
|
Shi H, Lee HK, Pan Y, Lau KC, Yiu SM, Lam WWY, Man WL, Lau TC. Structure and Reactivity of a Manganese(VI) Nitrido Complex Bearing a Tetraamido Macrocyclic Ligand. J Am Chem Soc 2021; 143:15863-15872. [PMID: 34498856 DOI: 10.1021/jacs.1c08072] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Manganese complexes in +6 oxidation state are rare. Although a number of Mn(VI) nitrido complexes have been generated in solution via one-electron oxidation of the corresponding Mn(V) nitrido species, they are too unstable to isolate. Herein we report the isolation and the X-ray structure of a Mn(VI) nitrido complex, [MnVI(N)(TAML)]- (2), which was obtained by one-electron oxidation of [MnV(N)(TAML)]2- (1). 2 undergoes N atom transfer to PPh3 and styrenes to give Ph3P═NH and aziridines, respectively. A Hammett study for various p-substituted styrenes gives a V-shaped plot; this is rationalized by the ability of 2 to function as either an electrophile or a nucleophile. 2 also undergoes hydride transfer reactions with NADH analogues, such as 10-methyl-9,10-dihydroacridine (AcrH2) and 1-benzyl-1,4-dihydronicotinamide (BNAH). A kinetic isotope effect of 7.3 was obtained when kinetic studies were carried out with AcrH2 and AcrD2. The reaction of 2 with NADH analogues results in the formation of [MnV(N)(TAML-H+)]- (3), which was characterized by ESI/MS, IR spectroscopy, and X-ray crystallography. These results indicate that this reaction occurs via an initial "separated CPET" (separated concerted proton-electron transfer) mechanism; that is, there is a concerted transfer of 1 e- + 1 H+ from AcrH2 (or BNAH) to 2, in which the electron is transferred to the MnVI center, while the proton is transferred to a carbonyl oxygen of TAML rather than to the nitrido ligand.
Collapse
Affiliation(s)
- Huatian Shi
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yi Pan
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Shek-Man Yiu
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - William W Y Lam
- Faculty of Science and Technology, Technological and Higher Education Institute of Hong Kong, Tsing Yi Road, Tsing Yi Island, Hong Kong, China
| | - Wai-Lun Man
- Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| |
Collapse
|
10
|
Halides of macrocyclic silver(II) complexes: Crystal structures with hydrogen bond network and reaction kinetics of the decomposition. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
11
|
Hong YH, Jang Y, Ezhov R, Seo MS, Lee YM, Pandey B, Hong S, Pushkar Y, Fukuzumi S, Nam W. A Highly Reactive Chromium(V)–Oxo TAML Cation Radical Complex in Electron Transfer and Oxygen Atom Transfer Reactions. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00079] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Young Hyun Hong
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yuri Jang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Roman Ezhov
- Department of Physics and Astronomy, Purdue University 525 Northwestern Avenue, West Lafayette, Indiana 47907, United States
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Bhawana Pandey
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Seungwoo Hong
- Department of Chemistry, Sookmyung Women’s University, Seoul 04310, Korea
| | - Yulia Pushkar
- Department of Physics and Astronomy, Purdue University 525 Northwestern Avenue, West Lafayette, Indiana 47907, United States
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, People’s Republic of China
| |
Collapse
|
12
|
van Leest NP, van der Vlugt JI, de Bruin B. Catalytic Chemoselective Sulfimidation with an Electrophilic [Co III (TAML)] - -Nitrene Radical Complex*. Chemistry 2021; 27:371-378. [PMID: 32810326 PMCID: PMC7839782 DOI: 10.1002/chem.202003566] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Indexed: 12/16/2022]
Abstract
The cobalt species PPh4 [CoIII (TAMLred )] is a competent and stable catalyst for the sulfimidation of (aryl)(alkyl)-substituted sulfides with iminoiodinanes, reaching turnover numbers up to 900 and turnover frequencies of 640 min-1 under mild and aerobic conditions. The sulfimidation proceeds in a highly chemoselective manner, even in the presence of alkenes or weak C-H bonds, as supported by inter- and intramolecular competition experiments. Functionalization of the sulfide substituent with various electron-donating and electron-withdrawing arenes and several alkyl, benzyl and vinyl fragments is tolerated, with up to quantitative product yields. Sulfimidation of phenyl allyl sulfide led to [2,3]-sigmatropic rearrangement of the initially formed sulfimide species to afford the corresponding N-allyl-S-phenyl-thiohydroxylamines as attractive products. Mechanistic studies suggest that the actual nitrene transfer to the sulfide proceeds via (previously characterized) electrophilic nitrene radical intermediates that afford the sulfimide products via electronically asynchronous transition states, in which SET from the sulfide to the nitrene radical complex precedes N-S bond formation in a single concerted process.
Collapse
Affiliation(s)
- Nicolaas P. van Leest
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Groupvan ‘t Hoff Institute for Molecular SciencesUniversity of Amsterdam (UvA)Science Park 9041098XHAmsterdamThe Netherlands
| | - Jarl Ivar van der Vlugt
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Groupvan ‘t Hoff Institute for Molecular SciencesUniversity of Amsterdam (UvA)Science Park 9041098XHAmsterdamThe Netherlands
- Current address: Bioinspired Coordination Chemistry &, Homogeneous Catalysis GroupInstitute of ChemistryCarl von Ossietzky University OldenburgCarl-von-Ossietzky-Strasse 9–11.26129OldenburgGermany
| | - Bas de Bruin
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Groupvan ‘t Hoff Institute for Molecular SciencesUniversity of Amsterdam (UvA)Science Park 9041098XHAmsterdamThe Netherlands
| |
Collapse
|
13
|
van Leest NP, Tepaske MA, Venderbosch B, Oudsen JPH, Tromp M, van der Vlugt JI, de Bruin B. Electronically Asynchronous Transition States for C–N Bond Formation by Electrophilic [CoIII(TAML)]-Nitrene Radical Complexes Involving Substrate-to-Ligand Single-Electron Transfer and a Cobalt-Centered Spin Shuttle. ACS Catal 2020; 10:7449-7463. [PMID: 35912398 PMCID: PMC9333348 DOI: 10.1021/acscatal.0c01343] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
The
oxidation state of the redox noninnocent tetra-amido macrocyclic
ligand (TAML) scaffold was recently shown to affect the formation
of nitrene radical species on cobalt(III) upon reaction with PhI=NNs
[van
LeestN. P.; 2020, 142, 552−56331846578]. For the neutral [CoIII(TAMLsq)] complex, this
leads to the doublet (S = 1/2) mono-nitrene radical species [CoIII(TAMLq)(N•Ns)(Y)] (bearing an unidentified
sixth ligand Y in at least the frozen state), while a triplet (S = 1) bis-nitrene radical species [CoIII(TAMLq)(N•Ns)2]– is generated from the anionic [CoIII(TAMLred)]– complex. The one-electron-reduced
Fischer-type nitrene radicals (N•Ns–) are formed through single (mono-nitrene) or double (bis-nitrene)
ligand-to-substrate single-electron transfer (SET). In this work,
we describe the reactivity and mechanisms of these nitrene radical
complexes in catalytic aziridination. We report that [CoIII(TAMLsq)] and [CoIII(TAMLred)]– are both effective catalysts for chemoselective (C=C
versus C–H bonds) and diastereoselective aziridination of styrene
derivatives, cyclohexane, and 1-hexene under mild and even aerobic
(for [CoIII(TAMLred)]–) conditions.
Experimental (Hammett plots; [CoIII(TAML)]-nitrene radical formation and quantification
under catalytic conditions; single-turnover experiments; and tests
regarding catalyst decomposition, radical inhibition, and radical
trapping) in combination with computational (density functional theory
(DFT), N-electron valence state perturbation theory corrected complete
active space self-consistent field (NEVPT2-CASSCF)) studies reveal
that [CoIII(TAMLq)(N•Ns)(Y)], [CoIII(TAMLq)(N•Ns)2]–, and [CoIII(TAMLsq)(N•Ns)]– are key electrophilic intermediates
in aziridination reactions. Surprisingly, the electrophilic one-electron-reduced
Fischer-type nitrene radicals do not react as would be expected for
nitrene radicals (i.e., via radical addition and radical rebound).
Instead, nitrene transfer proceeds through unusual electronically
asynchronous transition states, in which the (partial) styrene substrate
to TAML ligand (single-) electron transfer precedes C–N coupling.
The actual C–N bond formation processes are best described
as involving a nucleophilic attack of the nitrene (radical) lone pair
at the thus (partially) formed styrene radical cation. These processes
are coupled to TAML-to-cobalt and cobalt-to-nitrene single-electron
transfer, effectively leading to the formation of an amido-γ-benzyl
radical (NsN––CH2–•CH–Ph) bound to an intermediate spin (S = 1) cobalt(III) center. Hence, the TAML moiety can be
regarded to act as a transient electron acceptor, the cobalt center
behaves as a spin shuttle, and the nitrene radical acts as a nucleophile.
Such a mechanism was hitherto unknown for cobalt-catalyzed hypovalent
group transfer and the more general transition-metal-catalyzed nitrene
transfer to alkenes but is now shown to complement the known concerted
and stepwise mechanisms for N-group transfer.
Collapse
|
14
|
van Leest NP, Tepaske MA, Oudsen JPH, Venderbosch B, Rietdijk NR, Siegler MA, Tromp M, van der Vlugt JI, de Bruin B. Ligand Redox Noninnocence in [Co III(TAML)] 0/- Complexes Affects Nitrene Formation. J Am Chem Soc 2019; 142:552-563. [PMID: 31846578 PMCID: PMC6956250 DOI: 10.1021/jacs.9b11715] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
The redox noninnocence of the TAML scaffold in cobalt-TAML
(tetra-amido
macrocyclic ligand) complexes has been under debate since 2006. In
this work, we demonstrate with a variety of spectroscopic measurements
that the TAML backbone in the anionic complex [CoIII(TAMLred)]– is truly redox noninnocent
and that one-electron oxidation affords [CoIII(TAMLsq)]. Multireference (CASSCF) calculations show that the electronic
structure of [CoIII(TAMLsq)] is best described as an
intermediate spin (S = 1) cobalt(III) center that
is antiferromagnetically coupled to a ligand-centered radical, affording
an overall doublet (S = 1/2) ground-state. Reaction
of the cobalt(III)-TAML complexes with PhINNs as a nitrene precursor
leads to TAML-centered oxidation and produces nitrene radical complexes
without oxidation of the metal ion. The ligand redox state (TAMLred or TAMLsq) determines whether mono- or bis-nitrene
radical complexes are formed. Reaction of [CoIII(TAMLsq)] or [CoIII(TAMLred)]– with PhINNs results in the formation of [CoIII(TAMLq)(N•Ns)] and [CoIII(TAMLq)(N•Ns)2]–, respectively. Herein, ligand-to-substrate
single-electron transfer results in one-electron-reduced Fischer-type
nitrene radicals (N•Ns–) that are intermediates in catalytic nitrene transfer to styrene.
These nitrene radical species were characterized by EPR, XANES, and
UV–vis spectroscopy, high-resolution mass spectrometry, magnetic
moment measurements, and supporting CASSCF calculations.
Collapse
Affiliation(s)
| | | | | | | | | | - Maxime A Siegler
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | | | | | | |
Collapse
|