1
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Morris RH. Reactivity umpolung (reversal) of ligands in transition metal complexes. Chem Soc Rev 2024; 53:2808-2827. [PMID: 38353155 DOI: 10.1039/d3cs00979c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The success and power of homogeneous catalysis derives in large part from the wide choice of transition metal ions and their ligands. This tutorial review introduces examples where the reactivity of a ligand is completely reversed (umpolung) from Lewis basic/nucleophilic to acidic/electrophilic or vice versa on changing the metal and co-ligands. Understanding this phenomenon will assist in the rational design of catalysts and the understanding of metalloenzyme mechanisms. Labelling a metal and ligand with Seebach donor and acceptor labels helps to identify whether a reaction involving the intermolecular attack on the ligand is displaying native reactivity or reactivity umpolung. This has been done for complexes of nitriles, carbonyls, isonitriles, dinitrogen, Fischer carbenes, alkenes, alkynes, hydrides, methyls, methylidenes and alkylidenes, silylenes, oxides, imides/nitrenes, alkylidynes, methylidynes, and nitrides. The electronic influence of the metal and co-ligands is discussed in terms of the energy of (HOMO) d electrons. The energy can be related to the pKLACa (LAC is ligand acidity constant) of the theoretical hydride complexes [H-[M]-L]+ formed by the protonation of pair of valence d electrons on the metal in the [M-L] complex. Preliminary findings indicate that a negative pKLACa indicates that nucleophilic attack by a carbanion or amine on the ligand will likely occur while a positive pKLACa indicates that electrophilic attack by strong acids on the ligand will usually occur when the ligand is nitrile, carbonyl, isonitrile, alkene and η6-arene.
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Affiliation(s)
- Robert H Morris
- Department of Chemistry, University of Toronto, 80 Saint George St., Toronto, Ontario, Canada, M5S3H6.
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2
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Morton M, Tay BY, Mah JJ, White AJ, Nobbs JD, van Meurs M, Britovsek GJ. Hydrogen Activation with Ru-PN 3P Pincer Complexes for the Conversion of C 1 Feedstocks. Inorg Chem 2024; 63:3393-3401. [PMID: 38330919 PMCID: PMC10880058 DOI: 10.1021/acs.inorgchem.3c04001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/18/2024] [Accepted: 01/23/2024] [Indexed: 02/10/2024]
Abstract
The hydrogenation of C1 feedstocks (CO and CO2) has been investigated using ruthenium complexes [RuHCl(CO)(PN3P)] as the catalyst. PN3P pincer ligands containing amines in the linker between the central pyridine donor and the phosphorus donors with bulky substituents (tert-butyl (1) or TMPhos (2)) are required to obtain mononuclear single-site catalysts that can be activated by the addition of KOtBu to generate stable five-coordinate complexes [RuH(CO)(PN3P-H)], whereby the pincer ligand has been deprotonated. Activation of hydrogen takes place via heterolytic cleavage to generate [RuH2(CO)(PN3P)], but in the presence of CO, coordination of CO occurs preferentially to give [RuH(CO)2(PN3P-H)]. This complex can be protonated to give the cationic complex [RuH(CO)2(PN3P)]+, but it is unable to activate H2 heterolytically. In the case of the less coordinating CO2, both ruthenium complexes 1 and 2 are highly efficient as CO2 hydrogenation catalysts in the presence of a base (DBU), which in the case of the TMPhos ligand results in a TON of 30,000 for the formation of formate.
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Affiliation(s)
- Matthew
D. Morton
- Department
of Chemistry, Imperial College London, Molecular Sciences Research Hub,
White City Campus, 82 Wood Lane, London W12 0BZ, United
Kingdom
| | - Boon Ying Tay
- Institute
of Sustainability for Chemicals, Energy and Environment (ICSE2), Agency
for Science, Technology and Research (A*STAR), 1 Pesek Road Jurong Island, Singapore 627833, Republic of Singapore
| | - Justin J.Q. Mah
- Institute
of Sustainability for Chemicals, Energy and Environment (ICSE2), Agency
for Science, Technology and Research (A*STAR), 1 Pesek Road Jurong Island, Singapore 627833, Republic of Singapore
| | - Andrew J.P. White
- Department
of Chemistry, Imperial College London, Molecular Sciences Research Hub,
White City Campus, 82 Wood Lane, London W12 0BZ, United
Kingdom
| | - James D. Nobbs
- Institute
of Sustainability for Chemicals, Energy and Environment (ICSE2), Agency
for Science, Technology and Research (A*STAR), 1 Pesek Road Jurong Island, Singapore 627833, Republic of Singapore
| | - Martin van Meurs
- Institute
of Sustainability for Chemicals, Energy and Environment (ICSE2), Agency
for Science, Technology and Research (A*STAR), 1 Pesek Road Jurong Island, Singapore 627833, Republic of Singapore
| | - George J.P. Britovsek
- Department
of Chemistry, Imperial College London, Molecular Sciences Research Hub,
White City Campus, 82 Wood Lane, London W12 0BZ, United
Kingdom
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3
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Leitner Z, Císařová I, Štěpnička P. Coordination behaviour of a hybrid phosphinoguanidine ligand. NEW J CHEM 2022. [DOI: 10.1039/d1nj05237c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A triphenylphosphine derivative equipped with a guanidine substituent in the ortho position readily forms P,N-chelate complexes with Pd(ii) and Pt(ii); however, the coordination of the guanidine moiety can be blocked by protonation.
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Affiliation(s)
- Zdeněk Leitner
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
| | - Petr Štěpnička
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
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4
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Bárta O, Císařová I, Štěpnička P. The protonation state governs the coordination of phosphinoferrocene guanidines. Dalton Trans 2021; 50:14662-14671. [PMID: 34585205 DOI: 10.1039/d1dt02884g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Compared to phosphines with guanidinium tags, studied as polar ligands for aqueous catalysis, their counterparts bearing guanidine substituents received only limited attention. This contribution focuses on the coordination of phosphinoferrocene guanidine Ph2PfcNC(NHiPr)2 (1iPr, fc = ferrocene-1,1'-diyl) as a hybrid, P,N-donor ligand to Group 10 metals. In its native state, 1iPr coordinated as a P,N-chelating ligand, affording [M(X)(Y)(1iPr-κ2P,N)] (M/X/Y = Pd/Cl/Cl, Pd/Br/4-C6H4CN, Pt/Cl/Cl; the corresponding Ni(II) complex was not isolated). While [PdCl2(1iPr-κ2P,N)] converted into [PdCl(1iPr-κ3Fe,P,N)]+ species with Fe-Pd interaction, upon chloride removal, the analogous Pt(II) complex dimerised into [Pt2(μ-Cl)2(1iPr-κ2P,N)2]2+. Deprotonation of [PdCl2(1iPr-κ2P,N)] produced a unique, doubly chelating phosphinoguanidinate complex [PdCl{(1iPr-H)-κ3P,N,N'}], which was smoothly converted into [Pd(MeCN){(1iPr-H)-κ3P,N,N'}][SbF6]. The latter, a convenient starting material for substitution reactions, was used to prepare either [Pd(L){(1iPr-H)-κ3P,N,N'}][SbF6] (L = 4-(dimethylamino)pyridine and 2-phenylpyridine), by simple substitution, or the hydroxide and acetylacetonate (acac) complexes, [Pd2(μ-OH)2(1iPr-κ2P,N)2][SbF6]2 and [Pd(acac)(1iPr-κ2P,N)][SbF6], by substitution with concomitant proton transfer. In contrast, protonation of the guanidine moiety prevented its coordination, as shown in reactions of the salts (1iPrH)Cl and (1iPrH)[SbF6]. Depending on the metal-to-ligand ratio, adding (1iPrH)[SbF6] to [PdCl2(MeCN)2] produced [Pd2Cl2(μ-Cl)2(1iPrH-κP)2][SbF6]2 or [PdCl2(1iPrH-κP)2][SbF6]2. Analogous reactions involving (1iPrH)Cl were more complicated due to competing coordination of the chloride anion, leading to (in addition to other compounds) the zwitterionic complex [PdCl3(1iPrH-κP)], which was alternatively obtained by selective protonation of [PdCl2(1iPr-κ2P,N)] with HCl. Apparently, the protonation state of the guanidine moiety controls the coordination behaviour of phosphinoferrocene guanidines.
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Affiliation(s)
- Ondřej Bárta
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Petr Štěpnička
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
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5
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Wiedner ES, Preston AZ, Helm ML, Appel AM. Thermodynamic Trends for Reduction of CO by Molecular Complexes. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric S. Wiedner
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
| | - Andrew Z. Preston
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
| | - Monte L. Helm
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
| | - Aaron M. Appel
- Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
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Manankandayalage C, Unruh DK, Krempner C. Small Molecule Activation with Intramolecular "Inverse" Frustrated Lewis Pairs. Chemistry 2021; 27:6263-6273. [PMID: 33567143 DOI: 10.1002/chem.202005143] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/29/2021] [Indexed: 12/25/2022]
Abstract
The intramolecular "inverse" frustrated Lewis pairs (FLPs) of general formula 1-BR2 -2-[(Me2 N)2 C=N]-C6 H4 (3-6) [BR2 =BMes2 (3), BC12 H8 , (4), BBN (5), BBNO (6)] were synthesized and structurally characterized by multinuclear NMR spectroscopy and X-ray analysis. These novel types of pre-organized FLPs, featuring strongly basic guanidino units rigidly linked to weakly Lewis acidic boryl moieties via an ortho-phenylene linker, are capable of activating H-H, C-H, N-H, O-H, Si-H, B-H and C=O bonds. 4 and 5 deprotonated terminal alkynes and acetylene to form the zwitterionic borates 1-(RC≡C-BR2 )-2-[(Me2 N)2 C=NH]-C6 H4 (R=Ph, H) and reacted with ammonia, BnNH2 and pyrrolidine, to generate the FLP adducts 1-(R2 HN→BR2 )-2-[(Me2 N)2 C=NH]-C6 H4 , where the N-H functionality is activated by intramolecular H-bond interactions. In addition, 5 was found to rapidly add across the double bond of H2 CO, PhCHO and PhNCO to form cyclic zwitterionic guanidinium borates in excellent yields. Likewise, 5 is capable of cleaving H2 , HBPin and PhSiH3 to form various amino boranes. Collectively, the results demonstrate that these new types of intramolecular FLPs featuring weakly Lewis acidic boryl and strongly basic guanidino moieties are as potent as conventional intramolecular FLPs with strongly Lewis acidic units in activating small molecules.
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Affiliation(s)
| | - Daniel K Unruh
- Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, Texas, USA
| | - Clemens Krempner
- Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, Texas, USA
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7
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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] [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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Bárta O, Gyepes R, Císařová I, Alemayehu A, Štěpnička P. Synthesis and study of Fe → Pd interactions in unsymmetric Pd(ii) complexes with phosphinoferrocene guanidine ligands. Dalton Trans 2020; 49:4225-4229. [PMID: 32196051 DOI: 10.1039/d0dt00812e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Readily available phosphinoferrocene guanidines coordinate Pd(ii) as P,N-chelating or κ3P,N,Fe-bound ligands. As the latter, they give rise to the first donor-asymmetric complexes featuring Fe-Pd dative bonds, which were studied using direct (spectroscopic and electrochemical) methods and theoretical (DFT) approaches.
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Affiliation(s)
- Ondřej Bárta
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Róbert Gyepes
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Adam Alemayehu
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
| | - Petr Štěpnička
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
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9
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Buss JA, Bailey GA, Oppenheim J, VanderVelde DG, Goddard WA, Agapie T. CO Coupling Chemistry of a Terminal Mo Carbide: Sequential Addition of Proton, Hydride, and CO Releases Ethenone. J Am Chem Soc 2019; 141:15664-15674. [DOI: 10.1021/jacs.9b07743] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua A. Buss
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
| | - Gwendolyn A. Bailey
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
| | - Julius Oppenheim
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
| | - David G. VanderVelde
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
| | - William A. Goddard
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, California 91125, United States
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10
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Whittaker T, Kumar KBS, Peterson C, Pollock MN, Grabow LC, Chandler BD. H2 Oxidation over Supported Au Nanoparticle Catalysts: Evidence for Heterolytic H2 Activation at the Metal–Support Interface. J Am Chem Soc 2018; 140:16469-16487. [DOI: 10.1021/jacs.8b04991] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Todd Whittaker
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - K. B. Sravan Kumar
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
| | - Christine Peterson
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Meagan N. Pollock
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Lars C. Grabow
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
| | - Bert D. Chandler
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
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11
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Morales Salazar D, Gupta AK, Orthaber A. Reactivity studies of an imine-functionalised phosphaalkene; unusual electrostatic and supramolecular stabilisation of a σ2λ3-phosphorus motif via hydrogen bonding. Dalton Trans 2018; 47:10404-10409. [DOI: 10.1039/c8dt01607k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protonation with strong acids at an imine over addition to a phosphaalkene; resulting adducts display hydrogen bonding.
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Affiliation(s)
- Daniel Morales Salazar
- Molecular Inorganic Chemistry
- Department of Chemistry - Ångström Laboratories
- Uppsala University
- Sweden
| | - Arvind Kumar Gupta
- Molecular Inorganic Chemistry
- Department of Chemistry - Ångström Laboratories
- Uppsala University
- Sweden
| | - Andreas Orthaber
- Molecular Inorganic Chemistry
- Department of Chemistry - Ångström Laboratories
- Uppsala University
- Sweden
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12
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Labinger JA. Approaches to homogeneously catalyzed CO hydrogenation: A personal retrospective. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Lambic NS, Brown CA, Sommer RD, Ison EA. Dramatic Increase in the Rate of Olefin Insertion by Coordination of Lewis Acids to the Oxo Ligand in Oxorhenium(V) Hydrides. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00291] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nikola S. Lambic
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Caleb A. Brown
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Roger D. Sommer
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Elon A. Ison
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
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14
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Wiedner ES, Chambers MB, Pitman CL, Bullock RM, Miller AJM, Appel AM. Thermodynamic Hydricity of Transition Metal Hydrides. Chem Rev 2016; 116:8655-92. [PMID: 27483171 DOI: 10.1021/acs.chemrev.6b00168] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Transition metal hydrides play a critical role in stoichiometric and catalytic transformations. Knowledge of free energies for cleaving metal hydride bonds enables the prediction of chemical reactivity, such as for the bond-forming and bond-breaking events that occur in a catalytic reaction. Thermodynamic hydricity is the free energy required to cleave an M-H bond to generate a hydride ion (H(-)). Three primary methods have been developed for hydricity determination: the hydride transfer method establishes hydride transfer equilibrium with a hydride donor/acceptor pair of known hydricity, the H2 heterolysis method involves measuring the equilibrium of heterolytic cleavage of H2 in the presence of a base, and the potential-pKa method considers stepwise transfer of a proton and two electrons to give a net hydride transfer. Using these methods, over 100 thermodynamic hydricity values for transition metal hydrides have been determined in acetonitrile or water. In acetonitrile, the hydricity of metal hydrides spans a range of more than 50 kcal/mol. Methods for using hydricity values to predict chemical reactivity are also discussed, including organic transformations, the reduction of CO2, and the production and oxidation of hydrogen.
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Affiliation(s)
- Eric S Wiedner
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Matthew B Chambers
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Catherine L Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - R Morris Bullock
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Aaron M Appel
- Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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15
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Henthorn JT, Agapie T. Modulation of Proton-Coupled Electron Transfer through Molybdenum-Quinonoid Interactions. Inorg Chem 2016; 55:5337-42. [PMID: 27227812 DOI: 10.1021/acs.inorgchem.6b00331] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An expanded series of π-bound molybdenum-quinonoid complexes supported by pendant phosphines has been synthesized. These compounds formally span three protonation-oxidation states of the quinonoid fragment (catechol, semiquinone, quinone) and two different oxidation states of the metal (Mo(0), Mo(II)), notably demonstrating a total of two protons and four electrons accessible in the system. Previously, the reduced Mo(0)-catechol complex 1 and its reaction with dioxygen to yield the two-proton/two-electron oxidized Mo(0)-quinone compound 4 was explored, while, herein, the expansion of the series to include the two-electron oxidized Mo(II)-catechol complex 2, the one-proton/two-electron oxidized Mo-semiquinone complex 3, and the two-proton/four-electron oxidized Mo(II)-quinone complexes 5 and 6 is reported. Transfer of multiple equivalents of protons and electrons from the Mo(0) and Mo(II) catechol complexes, 1 and 2, to H atom acceptor TEMPO suggests the presence of weak O-H bonds. Although thermochemical analyses are hindered by the irreversibility of the electrochemistry of the present compounds, the reactivity observed suggests weaker O-H bonds compared to the free catechol, indicating that proton-coupled electron transfer can be facilitated significantly by the π-bound metal center.
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Affiliation(s)
- Justin T Henthorn
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
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16
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Maity A, Teets TS. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes. Chem Rev 2016; 116:8873-911. [DOI: 10.1021/acs.chemrev.6b00034] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ayan Maity
- Department of Chemistry, University of Houston, Lamar Fleming Jr. Building, 3585 Cullen Boulevard,
Room 112, Houston, Texas 77204-5003, United States
| | - Thomas S. Teets
- Department of Chemistry, University of Houston, Lamar Fleming Jr. Building, 3585 Cullen Boulevard,
Room 112, Houston, Texas 77204-5003, United States
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17
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Khosrowabadi Kotyk JF, Ziller JW, Yang JY. Copper tetradentate N 2Py 2 complexes with pendant bases in the secondary coordination sphere: improved ligand synthesis and protonation studies. J COORD CHEM 2016. [DOI: 10.1080/00958972.2015.1130223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
| | - Joseph W. Ziller
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Jenny Y. Yang
- Department of Chemistry, University of California, Irvine, CA, USA
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18
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Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes. Inorg Chem 2015. [DOI: 10.1021/acs.inorgchem.5b00633] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2013. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.09.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Osyanin VA, Osipov DV, Klimochkin YN. Reaction of 2,4-Di-tert-butyl-6-[(dimethylamino)methyl]phenol with diazabicyclo[5.4.0]undec-7-ene. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2015. [DOI: 10.1134/s1070428015010236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Teets TS, Labinger JA, Bercaw JE. Guanidine-Functionalized Rhenium Cyclopentadienyl Carbonyl Complexes: Synthesis and Cooperative Activation of H–H and O–H Bonds. Organometallics 2014. [DOI: 10.1021/om500650b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Thomas S. Teets
- Arnold and Mabel Beckman
Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California, United States
| | - Jay A. Labinger
- Arnold and Mabel Beckman
Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California, United States
| | - John E. Bercaw
- Arnold and Mabel Beckman
Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California, United States
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Wiedner ES, Appel AM. Thermochemical Insight into the Reduction of CO to CH3OH with [Re(CO)]+ and [Mn(CO)]+ Complexes. J Am Chem Soc 2014; 136:8661-8. [DOI: 10.1021/ja502316e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Eric S. Wiedner
- Physical Sciences
Division, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
| | - Aaron M. Appel
- Physical Sciences
Division, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
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