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McMillion ND, Bruch QJ, Chen CH, Hasanayn F, Miller AJM. Synthesis and bonding analysis of pentagonal bipyramidal rhenium carboxamide oxo complexes. Dalton Trans 2023; 52:15115-15123. [PMID: 37814941 DOI: 10.1039/d3dt02617e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Seven-coordinate rhenium oxo complexes supported by a tetradentate bipyridine carboxamide/carboxamidate ligand are reported. The neutral dicarboxamide H2Phbpy-da ligand initially coordinates in an L4 (ONNO) fashion to an octahedral rhenium oxo precursor, yielding a seven-coordinate rhenium oxo complex. Subsequent deprotonation generates a new oxo complex featuring the dianionic (L2X2) carboxamidate (NNNN) form of the ligand. Computational studies provide insight into the relative stability of possible linkage isomers upon deprotonation. Structural studies and molecular orbital theory are employed to rationalize the relative isomer stability and provide insight into the rhenium-oxo bond order.
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Affiliation(s)
- Noah D McMillion
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
| | - Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon.
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
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2
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Bruch QJ, McMillion ND, Chen CH, Miller AJM. Oxidative Addition of a Phosphinite P-O Bond at Nickel. Inorg Chem 2023; 62:2389-2393. [PMID: 36693197 DOI: 10.1021/acs.inorgchem.2c04188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Oxidative addition is an essential elementary reaction in organometallic chemistry and catalysis. While a diverse array of oxidative addition reactions has been reported to date, examples of P-O bond activation are surprisingly rare. Herein, we report the ligand-templated oxidative addition of a phosphinite P-O bond in the diphosphinito aniline compound HN(2-OPiPr2-3,5-tBu-C6H2)2 [H(P2ONO)] at Ni0 to form (PONO)Ni(HPiPr2) after proton rearrangement. Notably, the P-O cleavage occurs selectively over an amine N-H bond activation. Additionally, the ligand cannibalization is reversible, as addition of XPR2 (X = Cl, Br; R = iPr, Cy) to (PONO)Ni(HPiPr2) readily produces either symmetric or unsymmetric (P2ONO)NiX species and free HPiPr2. Finally, the mechanisms of both the initial P-O bond cleavage and its subsequent reconstruction are investigated to provide further insight into how to target P-O bond activation.
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Affiliation(s)
- Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Noah D McMillion
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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3
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Bruch QJ, Tanushi A, Müller P, Radosevich AT. Metal-Ligand Role Reversal: Hydride-Transfer Catalysis by a Functional Phosphorus Ligand with a Spectator Metal. J Am Chem Soc 2022; 144:21443-21447. [PMID: 36378626 PMCID: PMC9712262 DOI: 10.1021/jacs.2c10200] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Hydride transfer catalysis is shown to be enabled by the nonspectator reactivity of a transition metal-bound low-symmetry tricoordinate phosphorus ligand. Complex 1·[Ru]+, comprising a nontrigonal phosphorus chelate (1, P(N(o-N(2-pyridyl)C6H4)2) and an inert metal fragment ([Ru] = (Me5C5)Ru), reacts with NaBH4 to give a metallohydridophosphorane (1H·[Ru]) by P-H bond formation. Complex 1H·[Ru] is revealed to be a potent hydride donor (ΔG°H-,exp < 41 kcal/mol, ΔG°H-,calc = 38 ± 2 kcal/mol in MeCN). Taken together, the reactivity of the 1·[Ru]+/1H·[Ru] pair comprises a catalytic couple, enabling catalytic hydrodechlorination in which phosphorus is the sole reactive site of hydride transfer.
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Affiliation(s)
- Quinton J. Bruch
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Akira Tanushi
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Peter Müller
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Alexander T. Radosevich
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Espinosa MR, Ertem MZ, Barakat M, Bruch QJ, Deziel AP, Elsby MR, Hasanayn F, Hazari N, Miller AJM, Pecoraro MV, Smith AM, Smith NE. Correlating Thermodynamic and Kinetic Hydricities of Rhenium Hydrides. J Am Chem Soc 2022; 144:17939-17954. [PMID: 36130605 DOI: 10.1021/jacs.2c07192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of hydride transfer from Re(Rbpy)(CO)3H (bpy = 4,4'-R-2,2'-bipyridine; R = OMe, tBu, Me, H, Br, COOMe, CF3) to CO2 and seven different cationic N-heterocycles were determined. Additionally, the thermodynamic hydricities of complexes of the type Re(Rbpy)(CO)3H were established primarily using computational methods. Linear free-energy relationships (LFERs) derived by correlating thermodynamic and kinetic hydricities indicate that, in general, the rate of hydride transfer increases as the thermodynamic driving force for the reaction increases. Kinetic isotope effects range from inverse for hydride transfer reactions with a small driving force to normal for reactions with a large driving force. Hammett analysis indicates that hydride transfer reactions with greater thermodynamic driving force are less sensitive to changes in the electronic properties of the metal hydride, presumably because there is less buildup of charge in the increasingly early transition state. Bronsted α values were obtained for a range of hydride transfer reactions and along with DFT calculations suggest the reactions are concerted, which enables the use of Marcus theory to analyze hydride transfer reactions involving transition metal hydrides. It is notable, however, that even slight perturbations in the steric properties of the Re hydride or the hydride acceptor result in large deviations in the predicted rate of hydride transfer based on thermodynamic driving forces. This indicates that thermodynamic considerations alone cannot be used to predict the rate of hydride transfer, which has implications for catalyst design.
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Affiliation(s)
- Matthew R Espinosa
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Mehmed Z Ertem
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Mariam Barakat
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Anthony P Deziel
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Matthew R Elsby
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Nilay Hazari
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Matthew V Pecoraro
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Allison M Smith
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nicholas E Smith
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
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Martin JA, Bader TK, Bruch QJ, McCulley CM, Zinn SR, Anderson CB, Applegate LC, Aviles-Martin CJ, Bresnahan BL, Cool NI, DeYoung JL, Donaghy C, Douglas L, Harris CM, Hu DD, Murphy SE, Nyansa MMS, Patil A, Starr HE, Strasser JW, Troiano JL. The COVID-19 Pandemic as a Stress Test for Laboratory Safety Teams. ACS Chem Health Saf 2022. [DOI: 10.1021/acs.chas.2c00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jessica A. Martin
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Taysir K. Bader
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Quinton J. Bruch
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Calla M. McCulley
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sarah R. Zinn
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Constance B. Anderson
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Lindsey C. Applegate
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | | | - Brady L. Bresnahan
- Department of Chemical Engineering and Materials Science, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Nicholas I. Cool
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Jessica L. DeYoung
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Caroline Donaghy
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Lacey Douglas
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Celina M. Harris
- Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Daniel D. Hu
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shannon E. Murphy
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Monica Mame Soma Nyansa
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Abhijeet Patil
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Hannah E. Starr
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Juliette W. Strasser
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jennifer L. Troiano
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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Abstract
Molybdenum complexes supported by tridentate pincer ligands are exceptional catalysts for dinitrogen fixation using chemical reductants, but little is known about their prospects for electrochemical reduction of dinitrogen. The viability of electrochemical N2 binding and splitting by a molybdenum(III) pincer complex, (pyPNP)MoBr3 (pyPNP = 2,6-bis(tBu2PCH2)-C5H3N)), is established in this work, providing a foundation for a detailed mechanistic study of electrode-driven formation of the nitride complex (pyPNP)Mo(N)Br. Electrochemical kinetic analysis, optical and vibrational spectroelectrochemical monitoring, and computational studies point to two concurrent reaction pathways: In the reaction-diffusion layer near the electrode surface, the molybdenum(III) precursor is reduced by 2e- and generates a bimetallic molybdenum(I) Mo2(μ-N2) species capable of N-N bond scission; and in the bulk solution away from the electrode surface, over-reduced molybdenum(0) species undergo chemical redox reactions via comproportionation to generate the same bimetallic molybdenum(I) species capable of N2 cleavage. The comproportionation reactions reveal the surprising intermediacy of dimolybdenum(0) complex trans,trans-[(pyPNP)Mo(N2)2](μ-N2) in N2 splitting pathways. The same "over-reduced" molybdenum(0) species was also found to cleave N2 upon addition of lutidinium, an acid frequently used in catalytic reduction of dinitrogen.
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Affiliation(s)
- Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Santanu Malakar
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, United States
| | - Alan S Goldman
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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Hu J, Bruch QJ, Miller AJM. Temperature and Solvent Effects on H 2 Splitting and Hydricity: Ramifications on CO 2 Hydrogenation by a Rhenium Pincer Catalyst. J Am Chem Soc 2021; 143:945-954. [PMID: 33383987 DOI: 10.1021/jacs.0c11110] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The catalytic hydrogenation of carbon dioxide holds immense promise for applications in sustainable fuel synthesis and hydrogen storage. Mechanistic studies that connect thermodynamic parameters with the kinetics of catalysis can provide new understanding and guide predictive design of improved catalysts. Reported here are thermochemical and kinetic analyses of a new pincer-ligated rhenium complex (tBuPOCOP)Re(CO)2 (tBuPOCOP = 2,6-bis(di-tert-butylphosphinito)phenyl) that catalyzes CO2 hydrogenation to formate with faster rates at lower temperatures. Because the catalyst follows the prototypical "outer sphere" hydrogenation mechanism, comprehensive studies of temperature and solvent effects on the H2 splitting and hydride transfer steps are expected to be relevant to many other catalysts. Strikingly large entropy associated with cleavage of H2 results in a strong temperature dependence on the concentration of [(tBuPOCOP)Re(CO)2H]- present during catalysis, which is further impacted by changing the solvent from toluene to tetrahydrofuran to acetonitrile. New methods for determining the hydricity of metal hydrides and formate at temperatures other than 298 K are developed, providing insight into how temperature can influence the favorability of hydride transfer during catalysis. These thermochemical insights guided the selection of conditions for CO2 hydrogenation to formate with high activity (up to 364 h-1 at 1 atm or 3330 h-1 at 20 atm of 1:1 H2:CO2). In cases where hydride transfer is the highest individual kinetic barrier, entropic contributions to outer sphere H2 splitting lead to a unique temperature dependence: catalytic activity increases as temperature decreases in tetrahydrofuran (200-fold increase upon cooling from 50 to 0 °C) and toluene (4-fold increase upon cooling from 100 to 50 °C). Ramifications on catalyst structure-function relationships are discussed, including comparisons between "outer sphere" mechanisms and "metal-ligand cooperation" mechanisms.
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Affiliation(s)
- Jenny Hu
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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8
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Bruch QJ, Connor GP, McMillion ND, Goldman AS, Hasanayn F, Holland PL, Miller AJM. Considering Electrocatalytic Ammonia Synthesis via Bimetallic Dinitrogen Cleavage. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02606] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Quinton J. Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Gannon P. Connor
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Noah D. McMillion
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alan S. Goldman
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Patrick L. Holland
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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9
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Bruch QJ, Miller AJ. A bis(arylphosphinito)amide pincer ligand that binds nickel forming six-membered metallacycles. Polyhedron 2020. [DOI: 10.1016/j.poly.2020.114380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bruch QJ, Connor GP, Chen CH, Holland PL, Mayer JM, Hasanayn F, Miller AJM. Dinitrogen Reduction to Ammonium at Rhenium Utilizing Light and Proton-Coupled Electron Transfer. J Am Chem Soc 2019; 141:20198-20208. [DOI: 10.1021/jacs.9b10031] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Quinton J. Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Gannon P. Connor
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Patrick L. Holland
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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11
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Grajeda J, Nova A, Balcells D, Bruch QJ, Wragg DS, Heyn RH, Miller AJM, Tilset M. Synthesis and Characterization of Stable Gold(III) PNP Pincer Complexes. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Javier Grajeda
- Department of Chemistry University of North Carolina at Chapel Hill 27516‐3290 Chapel Hill NC USA
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
| | - Ainara Nova
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
| | - David Balcells
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
| | - Quinton J. Bruch
- Department of Chemistry University of North Carolina at Chapel Hill 27516‐3290 Chapel Hill NC USA
| | - David S. Wragg
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
| | | | - Alexander J. M. Miller
- Department of Chemistry University of North Carolina at Chapel Hill 27516‐3290 Chapel Hill NC USA
| | - Mats Tilset
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
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12
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Bruch QJ, Lindley BM, Askevold B, Schneider S, Miller AJM. A Ruthenium Hydrido Dinitrogen Core Conserved across Multielectron/Multiproton Changes to the Pincer Ligand Backbone. Inorg Chem 2018; 57:1964-1975. [PMID: 29419289 DOI: 10.1021/acs.inorgchem.7b02889] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of ruthenium(II) hydrido dinitrogen complexes supported by pincer ligands in different formal oxidation states have been prepared and characterized. Treating a ruthenium dichloride complex supported by the pincer ligand bis(di-tert-butylphosphinoethyl)amine (H-PNP) with reductant or base generates new five-coordinate cis-hydridodinitrogen ruthenium complexes each containing different forms of the pincer ligand. Further ligand transformations provide access to the first isostructural set of complexes featuring all six different forms of the pincer ligand. The conserved cis-hydridodinitrogen structure facilitates characterization of the π-donor, π-acceptor, and/or σ-donor properties of the ligands and assessment of the impact of ligand-centered multielectron/multiproton changes on N2 activation. Crystallographic studies, infrared spectroscopy, and 15N NMR spectroscopy indicate that N2 remains weakly activated in all cases, providing insight into the donor properties of the different pincer ligand states. Ramifications on applications of (pincer)Ru species in catalysis are considered.
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Affiliation(s)
- Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Brian M Lindley
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Bjorn Askevold
- University of Goettingen , Institute for Inorganic Chemistry, 37077 Goettingen, Germany
| | - Sven Schneider
- University of Goettingen , Institute for Inorganic Chemistry, 37077 Goettingen, Germany
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
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13
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Harris CF, Bayless MB, van Leest NP, Bruch QJ, Livesay BN, Bacsa J, Hardcastle KI, Shores MP, de Bruin B, Soper JD. Redox-Active Bis(phenolate) N-Heterocyclic Carbene [OCO] Pincer Ligands Support Cobalt Electron Transfer Series Spanning Four Oxidation States. Inorg Chem 2017; 56:12421-12435. [DOI: 10.1021/acs.inorgchem.7b01906] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Caleb F. Harris
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Michael B. Bayless
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Nicolaas P. van Leest
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Quinton J. Bruch
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Brooke N. Livesay
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - John Bacsa
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Kenneth I. Hardcastle
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - Bas de Bruin
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jake D. Soper
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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14
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Lindley BM, Bruch QJ, White PS, Hasanayn F, Miller AJM. Ammonia Synthesis from a Pincer Ruthenium Nitride via Metal-Ligand Cooperative Proton-Coupled Electron Transfer. J Am Chem Soc 2017; 139:5305-5308. [PMID: 28383261 DOI: 10.1021/jacs.7b01323] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The conversion of metal nitride complexes to ammonia may be essential to dinitrogen fixation. We report a new reduction pathway that utilizes ligating acids and metal-ligand cooperation to effect this conversion without external reductants. Weak acids such as 4-methoxybenzoic acid and 2-pyridone react with nitride complex [(H-PNP)RuN]+ (H-PNP = HN(CH2CH2PtBu2)2) to generate octahedral ammine complexes that are κ2-chelated by the conjugate base. Experimental and computational mechanistic studies reveal the important role of Lewis basic sites proximal to the acidic proton in facilitating protonation of the nitride. The subsequent reduction to ammonia is enabled by intramolecular 2H+/2e- proton-coupled electron transfer from the saturated pincer ligand backbone.
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Affiliation(s)
- Brian M Lindley
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Quinton J Bruch
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Peter S White
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut , Beirut 1107 2020, Lebanon
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
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