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Nurdin L, Yang Y, Neate PGN, Piers WE, Maron L, Neidig ML, Lin JB, Gelfand BS. Activation of ammonia and hydrazine by electron rich Fe(ii) complexes supported by a dianionic pentadentate ligand platform through a common terminal Fe(iii) amido intermediate. Chem Sci 2020; 12:2231-2241. [PMID: 34163989 PMCID: PMC8179247 DOI: 10.1039/d0sc06466a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We report the use of electron rich iron complexes supported by a dianionic diborate pentadentate ligand system, B2Pz4Py, for the coordination and activation of ammonia (NH3) and hydrazine (NH2NH2). For ammonia, coordination to neutral (B2Pz4Py)Fe(ii) or cationic [(B2Pz4Py)Fe(iii)]+ platforms leads to well characterized ammine complexes from which hydrogen atoms or protons can be removed to generate, fleetingly, a proposed (B2Pz4Py)Fe(iii)–NH2 complex (3Ar-NH2). DFT computations suggest a high degree of spin density on the amido ligand, giving it significant aminyl radical character. It rapidly traps the H atom abstracting agent 2,4,6-tri-tert-butylphenoxy radical (ArO˙) to form a C–N bond in a fully characterized product (2Ar), or scavenges hydrogen atoms to return to the ammonia complex (B2Pz4Py)Fe(ii)–NH3 (1Ar-NH3). Interestingly, when (B2Pz4Py)Fe(ii) is reacted with NH2NH2, a hydrazine bridged dimer, (B2Pz4Py)Fe(ii)–NH2NH2–Fe(ii)(B2Pz4Py) ((1Ar)2-NH2NH2), is observed at −78 °C and converts to a fully characterized bridging diazene complex, 4Ar, along with ammonia adduct 1Ar-NH3 as it is allowed to warm to room temperature. Experimental and computational evidence is presented to suggest that (B2Pz4Py)Fe(ii) induces reductive cleavage of the N–N bond in hydrazine to produce the Fe(iii)–NH2 complex 3Ar-NH2, which abstracts H˙ atoms from (1Ar)2-NH2NH2 to generate the observed products. All of these transformations are relevant to proposed steps in the ammonia oxidation reaction, an important process for the use of nitrogen-based fuels enabled by abundant first row transition metals. Synopsis: a highly reactive Fe(iii)–NH2 complex is generated via activation of ammonia or hydrazine in reactions of relevance to fundamental steps in ammonia oxidation processes mediated by an abundant, first row transition metal.![]()
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Affiliation(s)
- Lucie Nurdin
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Yan Yang
- LPCNO, Université de Toulouse, INSA, UPS Toulouse France
| | - Peter G N Neate
- Department of Chemistry, University of Rochester Rochester New York 14627 USA
| | - Warren E Piers
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Laurent Maron
- LPCNO, Université de Toulouse, INSA, UPS Toulouse France
| | - Michael L Neidig
- Department of Chemistry, University of Rochester Rochester New York 14627 USA
| | - Jian-Bin Lin
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Benjamin S Gelfand
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
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Dunn PL, Johnson SI, Kaminsky W, Bullock RM. Diversion of Catalytic C-N Bond Formation to Catalytic Oxidation of NH 3 through Modification of the Hydrogen Atom Abstractor. J Am Chem Soc 2020; 142:3361-3365. [PMID: 32009401 DOI: 10.1021/jacs.9b13706] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We report that (TMP)Ru(NH3)2 (TMP = tetramesitylporphryin) is a molecular catalyst for oxidation of ammonia to dinitrogen. An aryloxy radical, tri-tert-butylphenoxyl (ArO·), abstracts H atoms from a bound ammonia ligand of (TMP)Ru(NH3)2, leading to the discovery of a new catalytic C-N coupling to the para position of ArO· to form 4-amino-2,4,6-tri-tert-butylcyclohexa-2,5-dien-1-one. Modification of the aryloxy radical to 2,6-di-tert-butyl-4-tritylphenoxyl radical, which contains a trityl group at the para position, prevents C-N coupling and diverts the reaction to catalytic oxidation of NH3 to give N2. We achieved 125 ± 5 turnovers at 22 °C for oxidation of NH3, the highest turnover number (TON) reported to date for a molecular catalyst.
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Affiliation(s)
- Peter L Dunn
- Center for Molecular Electrocatalysis , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Werner Kaminsky
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
| | - R Morris Bullock
- Center for Molecular Electrocatalysis , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
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Tanaka H, Hitaoka S, Umehara K, Yoshizawa K, Kuwata S. Mechanistic Study on Catalytic Disproportionation of Hydrazine by a Protic Pincer‐Type Iron Complex through Proton‐Coupled Electron Transfer. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201901135] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hiromasa Tanaka
- School of Liberal Arts and Sciences Daido University Minami-ku Nagoya 457‐8530 Japan
| | - Seiji Hitaoka
- Institute of Materials Chemistry and Engineering Kyushu University Nishi-ku Fukuoka 819‐0395 Japan
| | - Kazuki Umehara
- Department of Chemical Science and Engineering School of Materials and Chemical Technology Tokyo Institute of Technology 2‐12‐1 E4‐1 O‐Okayama Meguro‐ku Tokyo 152‐8552 Japan
| | - Kazunari Yoshizawa
- Institute of Materials Chemistry and Engineering Kyushu University Nishi-ku Fukuoka 819‐0395 Japan
| | - Shigeki Kuwata
- Department of Chemical Science and Engineering School of Materials and Chemical Technology Tokyo Institute of Technology 2‐12‐1 E4‐1 O‐Okayama Meguro‐ku Tokyo 152‐8552 Japan
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Bhattacharya P, Heiden ZM, Chambers GM, Johnson SI, Bullock RM, Mock MT. Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Papri Bhattacharya
- Center for Molecular Electrocatalysis Pacific Northwest National Laboratory P.O. Box 999 Richland WA 99352 USA
| | | | - Geoffrey M. Chambers
- Center for Molecular Electrocatalysis Pacific Northwest National Laboratory P.O. Box 999 Richland WA 99352 USA
| | - Samantha I. Johnson
- Center for Molecular Electrocatalysis Pacific Northwest National Laboratory P.O. Box 999 Richland WA 99352 USA
| | - R. Morris Bullock
- Center for Molecular Electrocatalysis Pacific Northwest National Laboratory P.O. Box 999 Richland WA 99352 USA
| | - Michael T. Mock
- Department of Chemistry and Biochemistry Montana State University Bozeman MT 59717 USA
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Bhattacharya P, Heiden ZM, Chambers GM, Johnson SI, Bullock RM, Mock MT. Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction. Angew Chem Int Ed Engl 2019; 58:11618-11624. [PMID: 31115120 DOI: 10.1002/anie.201903221] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/06/2019] [Indexed: 12/20/2022]
Abstract
Catalysts for the oxidation of NH3 are critical for the utilization of NH3 as a large-scale energy carrier. Molecular catalysts capable of oxidizing NH3 to N2 are rare. This report describes the use of [Cp*Ru(PtBu 2 NPh 2 )(15 NH3 )][BArF 4 ], (PtBu 2 NPh 2 =1,5-di(phenylaza)-3,7-di(tert-butylphospha)cyclooctane; ArF =3,5-(CF3 )2 C6 H3 ), to catalytically oxidize NH3 to dinitrogen under ambient conditions. The cleavage of six N-H bonds and the formation of an N≡N bond was achieved by coupling H+ and e- transfers as net hydrogen atom abstraction (HAA) steps using the 2,4,6-tri-tert-butylphenoxyl radical (t Bu3 ArO. ) as the H atom acceptor. Employing an excess of t Bu3 ArO. under 1 atm of NH3 gas at 23 °C resulted in up to ten turnovers. Nitrogen isotopic (15 N) labeling studies provide initial mechanistic information suggesting a monometallic pathway during the N⋅⋅⋅N bond-forming step in the catalytic cycle.
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Affiliation(s)
- Papri Bhattacharya
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA
| | | | - Geoffrey M Chambers
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA
| | - R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA
| | - Michael T Mock
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
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Abbenseth J, Delony D, Neben MC, Würtele C, de Bruin B, Schneider S. Interconversion of Phosphinyl Radical and Phosphinidene Complexes by Proton Coupled Electron Transfer. Angew Chem Int Ed Engl 2019; 58:6338-6341. [PMID: 30840783 PMCID: PMC6519162 DOI: 10.1002/anie.201901470] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Indexed: 12/04/2022]
Abstract
The isolable complex [Os(PHMes*)H(PNP)] (Mes*=2,4,6-t Bu3 C6 H3 ; PNP=N{CHCHPt Bu2 }2 ) exhibits high phosphinyl radical character. This compound offers access to the phosphinidene complex [Os(PMes*)H(PNP)] by P-H proton coupled electron transfer (PCET). The P-H bond dissociation energy (BDE) was determined by isothermal titration calorimetry and supporting DFT computations. The phosphinidene product exhibits electrophilic reactivity as demonstrated by intramolecular C-H activation.
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Affiliation(s)
- Josh Abbenseth
- Georg-August-Universität GöttingenInstitut für Anorganische ChemieTammannstraße 437077GöttingenGermany
| | - Daniel Delony
- Georg-August-Universität GöttingenInstitut für Anorganische ChemieTammannstraße 437077GöttingenGermany
| | - Marc C. Neben
- Georg-August-Universität GöttingenInstitut für Anorganische ChemieTammannstraße 437077GöttingenGermany
| | - Christian Würtele
- Georg-August-Universität GöttingenInstitut für Anorganische ChemieTammannstraße 437077GöttingenGermany
| | - Bas de Bruin
- Van't Hoff Institute for Molecular Sciences (HIMS)University of Amsterdam (UvA)Science Park 9041098XHAmsterdamThe Netherlands
| | - Sven Schneider
- Georg-August-Universität GöttingenInstitut für Anorganische ChemieTammannstraße 437077GöttingenGermany
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Abbenseth J, Delony D, Neben MC, Würtele C, de Bruin B, Schneider S. Interconversion of Phosphinyl Radical and Phosphinidene Complexes by Proton Coupled Electron Transfer. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Josh Abbenseth
- Georg-August-Universität GöttingenInstitut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Daniel Delony
- Georg-August-Universität GöttingenInstitut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Marc C. Neben
- Georg-August-Universität GöttingenInstitut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Christian Würtele
- Georg-August-Universität GöttingenInstitut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Bas de Bruin
- Van't Hoff Institute for Molecular Sciences (HIMS)University of Amsterdam (UvA) Science Park 904 1098 XH Amsterdam The Netherlands
| | - Sven Schneider
- Georg-August-Universität GöttingenInstitut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
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Chang MC, Jesse KA, Filatov AS, Anderson JS. Reversible homolytic activation of water via metal-ligand cooperativity in a T-shaped Ni(ii) complex. Chem Sci 2019; 10:1360-1367. [PMID: 30809351 PMCID: PMC6354739 DOI: 10.1039/c8sc03719a] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/05/2018] [Indexed: 12/18/2022] Open
Abstract
A T-shaped Ni(ii) complex [Tol,PhDHPy]Ni has been prepared and characterized. EPR spectra and DFT calculations of this complex suggest that the electronic structure is best described as a high-spin Ni(ii) center antiferromagnetically coupled with a ligand-based radical. This complex reacts with water at room temperature to generate the dimeric complex [Tol,PhDHPy]Ni(μ-OH)Ni[Tol,PhDHPyH] which has been thoroughly characterized by SXRD, NMR, IR and deuterium-labeling experiments. Addition of simple ligands such as phosphines or pyridine displaces water and demonstrates the reversibility of water activation in this system. The water activation step has been examined by kinetic studies and DFT calculations which suggest an unusual homolytic reaction via a bimetallic mechanism. The ΔH ‡, ΔS ‡ and KIE (k H/k D) of the reaction are 5.5 kcal mol-1, -23.8 cal mol-1 K-1, and 2.4(1), respectively. In addition to the reversibility of water addition, this system is capable of activating water towards net O-atom transfer to substrates such as aromatic C-H bonds and phosphines. This reactivity is facilitated by the ability of the dihydrazonopyrrole ligand to accept H-atoms and illustrates the utility of metal ligand cooperation in activating O-H bonds with high bond dissociation energies.
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Affiliation(s)
- Mu-Chieh Chang
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - Kate A Jesse
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - Alexander S Filatov
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - John S Anderson
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
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