51
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Bellows SM, Arnet NA, Gurubasavaraj PM, Brennessel WW, Bill E, Cundari TR, Holland PL. The Mechanism of N-N Double Bond Cleavage by an Iron(II) Hydride Complex. J Am Chem Soc 2016; 138:12112-23. [PMID: 27598037 PMCID: PMC5499983 DOI: 10.1021/jacs.6b04654] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The use of hydride species for substrate reductions avoids strong reductants, and may enable nitrogenase to reduce multiple bonds without unreasonably low redox potentials. In this work, we explore the N═N bond cleaving ability of a high-spin iron(II) hydride dimer with concomitant release of H2. Specifically, this diiron(II) complex reacts with azobenzene (PhN═NPh) to perform a four-electron reduction, where two electrons come from H2 reductive elimination and the other two come from iron oxidation. The rate law of the H2 releasing reaction indicates that diazene binding occurs prior to H2 elimination, and the negative entropy of activation and inverse kinetic isotope effect indicate that H-H bond formation is the rate-limiting step. Thus, substrate binding causes reductive elimination of H2 that formally reduces the metals, and the metals use the additional two electrons to cleave the N-N multiple bond.
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Affiliation(s)
- Sarina M. Bellows
- Department of Chemistry, University of Rochester, Rochester, NY 14627
| | | | | | | | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, Mülheim an der Ruhr, Germany
| | - Thomas R. Cundari
- Department of Chemistry and CASCaM, University of North Texas, Denton, TX 76203
| | - Patrick L. Holland
- Department of Chemistry, University of Rochester, Rochester, NY 14627
- Department of Chemistry, Yale University, New Haven, CT 06520
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52
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Bellows SM, Brennessel WW, Holland PL. Effects of Ligand Halogenation on the Electron Localization, Geometry and Spin State of Low-Coordinate (β-Diketiminato)iron Complexes. Eur J Inorg Chem 2016; 2016:3344-3355. [PMID: 28835739 PMCID: PMC5563838 DOI: 10.1002/ejic.201600112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 11/05/2022]
Abstract
This contribution explores the influences of incorporating electron-withdrawing CF3 and halide groups into β-diketiminate iron complexes of tetrazene and isocyanide. The synthesis of a new halogenated β-diketimine (LCF3,ClH) was accomplished via two different methods, including a novel microwave-assisted synthesis that improves the yield of the difficult condensation. Treatment of an iron(II) complex of this ligand with reductant and azide gives two diiron complexes with novel tetrazenes as bridging ligands. Structural and Mössbauer data show that the bridging tetrazene is a radical anion. The halogenation of the supporting ligand also influences iron(I) complexes of the type LFe(CNtBu)2, which are low-spin and square-planar with alkyl substituents but high-spin and pseudotetrahedral with halogen substituents. DFT calculations suggest that the changes from halogenation come from a combination of steric and electronic effects, and that the electronic influence of ligand halogenation is minor.
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Affiliation(s)
- Sarina M Bellows
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
| | - William W Brennessel
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
| | - Patrick L Holland
- Department of Chemistry, Yale University 225, Prospect St, New Haven, CT 06520 USA, Homepage: http://holland.chem.yale.edu
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
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53
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Spasyuk DM, Carpenter SH, Kefalidis CE, Piers WE, Neidig ML, Maron L. Facile hydrogen atom transfer to iron(iii) imido radical complexes supported by a dianionic pentadentate ligand. Chem Sci 2016; 7:5939-5944. [PMID: 30034736 PMCID: PMC6024611 DOI: 10.1039/c6sc01433j] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/28/2016] [Indexed: 12/28/2022] Open
Abstract
Facile hydrogen atom transfer from toluene.
A dianionic tetrapodal pentadentate diborate ligand is introduced. This ligand forms a high spin neutral iron(ii) complex that reacts with a variety of organoazides to yield transient Fe(iii) imido radicals that are extremely potent hydrogen atom abstractors. The nature of these species is supported by full characterization of the Fe(iii) amido products, kinetic studies, density functional computations and Mössbauer spectroscopy on the –C6H4-p-tBu substituted derivative.
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Affiliation(s)
- Denis M Spasyuk
- University of Calgary , Department of Chemistry , 2500 University Drive N.W. , Calgary , Alberta , Canada T2N 1N4 .
| | - Stephanie H Carpenter
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA
| | - Christos E Kefalidis
- LPCNO , Université de Toulouse , INSA , UPS , CNRS , 135 avenue de Rangueil , F-31077 Toulouse , France
| | - Warren E Piers
- University of Calgary , Department of Chemistry , 2500 University Drive N.W. , Calgary , Alberta , Canada T2N 1N4 .
| | - Michael L Neidig
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA
| | - Laurent Maron
- LPCNO , Université de Toulouse , INSA , UPS , CNRS , 135 avenue de Rangueil , F-31077 Toulouse , France
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54
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Thacker NC, Lin Z, Zhang T, Gilhula JC, Abney CW, Lin W. Robust and Porous β-Diketiminate-Functionalized Metal–Organic Frameworks for Earth-Abundant-Metal-Catalyzed C–H Amination and Hydrogenation. J Am Chem Soc 2016; 138:3501-9. [DOI: 10.1021/jacs.5b13394] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Nathan C. Thacker
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Zekai Lin
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Teng Zhang
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - James C. Gilhula
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Carter W. Abney
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Wenbin Lin
- Department
of Chemistry, University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
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55
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Gehring H, Metzinger R, Braun B, Herwig C, Harder S, Ray K, Limberg C. An iron(ii) hydride complex of a ligand with two adjacent β-diketiminate binding sites and its reactivity. Dalton Trans 2016; 45:2989-96. [PMID: 26757878 PMCID: PMC5536248 DOI: 10.1039/c5dt04266f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
After lithiation of PYR-H2 (PYR = [(NC(Me)C(H)C(Me)NC6H3(iPr)2)2(C5H3N)](2-)) - the precursor of an expanded β-diketiminato ligand system with two binding pockets - with KN(TMS)2 the reaction of the resulting potassium salt with FeBr2 led to a dinuclear iron(ii) bromide complex [(PYR)Fe(μ-Br)2Fe] (1). Through treatment with KHBEt3 the bromide ligands could be replaced by hydrides to yield [PYR)Fe2(μ-H)2] (2), a distorted analogue of known β-diketiminato iron hydride complexes, as evidenced by NMR, Mößbauer and X-ray absorption spectroscopy, as well as by its reactivity: for instance, 2 reacts with the proton source lutidinium triflate via protonation of the hydride ligands to form an iron(ii) product [(PYR)Fe2(OTf)2] (4), while CO2 inserts into the Fe-H bonds generating the formate complex [(PYR)Fe2(μ-HCOO)2] (5); in the presence of traces of water partial hydrolysis occurs so that [(PYR)Fe2(μ-OH)(μ-HCOO)] (6) is isolated. Altogether, the iron(ii) chemistry supported by the PYR(2-) ligand is distinctly different from the one of nickel(ii), where both, the arrangement of the two binding pockets and the additional pyridyl donor led to diverging features as compared with the corresponding system based on the parent β-diketiminato ligand.
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Affiliation(s)
- Henrike Gehring
- Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, 12489 Berlin, Germany.
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56
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Bezdek MJ, Chirik PJ. Thermodynamics of N–H bond formation in bis(phosphine) molybdenum(ii) diazenides and the influence of the trans ligand. Dalton Trans 2016; 45:15922-15930. [PMID: 27378665 DOI: 10.1039/c6dt01932c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dinitrogen-derived molybdenum alkyldiazenides and alkylhydrazides were synthesized with various trans ligands. The thermodynamics of N–H bond formation were studied both experimentally and computationally.
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57
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Heins SP, Morris WD, Wolczanski PT, Lobkovsky EB, Cundari TR. Nitrene Insertion into CC and CH Bonds of Diamide Diimine Ligands Ligated to Chromium and Iron. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507463] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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58
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Heins SP, Morris WD, Wolczanski PT, Lobkovsky EB, Cundari TR. Nitrene Insertion into CC and CH Bonds of Diamide Diimine Ligands Ligated to Chromium and Iron. Angew Chem Int Ed Engl 2015; 54:14407-11. [DOI: 10.1002/anie.201507463] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Spencer P. Heins
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14850 (USA)
| | - Wesley D. Morris
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14850 (USA)
| | - Peter T. Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14850 (USA)
| | - Emil B. Lobkovsky
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14850 (USA)
| | - Thomas R. Cundari
- Department of Chemistry, Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas, Box 305070, Denton, TX 76203‐5070 (USA)
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59
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Olatunji-Ojo O, Cundari TR. Effect of Ligand Connectivity and Charge State on the Amination of C–H Bonds by Copper Amide Complexes. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Olayinka Olatunji-Ojo
- Molecular
Graphics and Computation Facility, College of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Thomas R. Cundari
- Department
of Chemistry, CASCaM, University of North Texas, 1155 Union Circle, No. 305070, Denton, Texas 76203-5017, United States
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60
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King AK, Buchard A, Mahon MF, Webster RL. Facile, Catalytic Dehydrocoupling of Phosphines Using β‐Diketiminate Iron(II) Complexes. Chemistry 2015; 21:15960-3. [DOI: 10.1002/chem.201503399] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Andrew K. King
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (UK)
| | - Antoine Buchard
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (UK)
| | - Mary F. Mahon
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (UK)
| | - Ruth L. Webster
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (UK)
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61
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Lee Y, Anderton KJ, Sloane FT, Ermert DM, Abboud KA, García-Serres R, Murray LJ. Reactivity of Hydride Bridges in High-Spin [3M-3(μ-H)] Clusters (M = FeII, CoII). J Am Chem Soc 2015; 137:10610-7. [PMID: 26270596 DOI: 10.1021/jacs.5b05204] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The designed [3M-3(μ-H)] clusters (M = Fe(II), Co(II)) Fe3H3L (1-H) and Co3H3L (2-H) [where L(3-) is a tris(β-diketiminate) cyclophane] were synthesized by treating the corresponding M3Br3L complexes with KBEt3H. From single-crystal X-ray analysis, the hydride ligands are sterically protected by the cyclophane ligand, and these complexes selectively react with CO2 over other unsaturated substrates (e.g., CS2, Me3SiCCH, C2H2, and CH3CN). The reaction of 1-H or 2-H with CO2 at room temperature yielded Fe3(OCHO)(H)2L (1-CO2) or Co3(OCHO)(H)2L (2-CO2), respectively, which evidence the differential reactivity of the hydride ligands within these complexes. The analogous reactions at elevated temperatures revealed a distinct difference in the reactivity pattern for 2-H as compared to 1-H; Fe3(OCHO)3L (1-3CO2) was generated from 1-H, while 2-H afforded only 2-CO2.
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Affiliation(s)
- Yousoon Lee
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - Kevin J Anderton
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - Forrest T Sloane
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - David M Ermert
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - Khalil A Abboud
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - Ricardo García-Serres
- Université Grenoble Alpes, LCBM/PMB and CEA, iRTSV/CBM/PMB and CNRS, UMR 5249, LCBM/PMB, 38000 Grenoble, France
| | - Leslie J Murray
- Center for Catalysis and Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
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62
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Chen C, Bellows SM, Holland PL. Tuning steric and electronic effects in transition-metal β-diketiminate complexes. Dalton Trans 2015; 44:16654-70. [PMID: 26244489 DOI: 10.1039/c5dt02215k] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
β-Diketiminates are widely used supporting ligands for building a range of metal complexes with different oxidation states, structures, and reactivities. This Perspective summarizes the steric and electronic influences of ligand substituents on these complexes, with an eye toward informing the design of new complexes with optimized properties. The backbone and N-aryl substituents can give significant steric effects on structure, reactivity and selectivity of reactions. The electron density on the metal can be tuned by installation of electron withdrawing or donating groups on the β-diketiminate ligand as well. Examples are shown from throughout the transition metal series to demonstrate different types of effects attributable to systematic variation of β-diketiminate ligands.
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Affiliation(s)
- Chi Chen
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA.
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63
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Cariou R, Shabaker JW. Iron-Catalyzed Chain Growth of Ethylene: In Situ Regeneration of ZnEt2 by Tandem Catalysis. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01231] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Renan Cariou
- BP Chemicals, Saltend, Hull HU12 8DS, United Kingdom
| | - John W. Shabaker
- BP Products North
America, 150 West Warrenville Road, Naperville, Illinois 60563, United States
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64
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Pappas I, Chirik PJ. Ammonia synthesis by hydrogenolysis of titanium-nitrogen bonds using proton coupled electron transfer. J Am Chem Soc 2015; 137:3498-501. [PMID: 25719966 DOI: 10.1021/jacs.5b01047] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The catalytic hydrogenolysis of the titanium-amide bond in (η(5)-C5Me4SiMe3)2Ti(Cl)NH2 to yield free ammonia is described. The rhodium hydride, (η(5)-C5Me5)(py-Ph)RhH (py-Ph = 2-phenylpyridine), serves as the catalyst and promotes N-H bond formation via hydrogen atom transfer. The N-H bond dissociation free energies of ammonia ligands have also been determined for titanocene and zirconocene complexes and reveal a stark dependence on metal identity and oxidation state. In all cases, the N-H BDFEs of coordinated NH3 decreases by >40 kcal/mol from the value in the free gas phase molecule.
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Affiliation(s)
- Iraklis Pappas
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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65
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Lee Y, Sloane FT, Blondin G, Abboud KA, García-Serres R, Murray LJ. Dinitrogen Activation Upon Reduction of a Triiron(II) Complex. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201409676] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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66
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Lee Y, Sloane FT, Blondin G, Abboud KA, García-Serres R, Murray LJ. Dinitrogen Activation Upon Reduction of a Triiron(II) Complex. Angew Chem Int Ed Engl 2014; 54:1499-503. [DOI: 10.1002/anie.201409676] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/09/2014] [Indexed: 11/09/2022]
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67
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Searles K, Fortier S, Khusniyarov MM, Carroll PJ, Sutter J, Meyer K, Mindiola DJ, Caulton KG. A cis-divacant octahedral and mononuclear iron(IV) imide. Angew Chem Int Ed Engl 2014; 53:14139-43. [PMID: 25327475 DOI: 10.1002/anie.201407156] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 08/26/2014] [Indexed: 01/08/2023]
Abstract
A rare, low-spin Fe(IV) imide complex [(pyrr2py)Fe=NAd] (pyrr2 py(2-) = bis(pyrrolyl)pyridine; Ad = 1-adamantyl) confined to a cis-divacant octahedral geometry, was prepared by reduction of N3Ad by the Fe(II) precursor [(pyrr2py)Fe(OEt2)]. The imide complex is low-spin with temperature-independent paramagnetism. In comparison to an authentic Fe(III) complex, such as [(pyrr2py)FeCl], the pyrr2py(2-) ligand is virtually redox innocent.
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Affiliation(s)
- Keith Searles
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (USA)
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68
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Searles K, Fortier S, Khusniyarov MM, Carroll PJ, Sutter J, Meyer K, Mindiola DJ, Caulton KG. Acis-Divacant Octahedral and Mononuclear Iron(IV) Imide. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201407156] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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69
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Milsmann C, Semproni SP, Chirik PJ. N–N Bond Cleavage of 1,2-Diarylhydrazines and N–H Bond Formation via H-Atom Transfer in Vanadium Complexes Supported by a Redox-Active Ligand. J Am Chem Soc 2014; 136:12099-107. [DOI: 10.1021/ja5062196] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Carsten Milsmann
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Scott P. Semproni
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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70
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Morris WD, Wolczanski PT, Sutter J, Meyer K, Cundari TR, Lobkovsky EB. Iron and chromium complexes containing tridentate chelates based on nacnac and imino- and methyl-pyridine components: triggering C-X bond formation. Inorg Chem 2014; 53:7467-84. [PMID: 25010819 DOI: 10.1021/ic500807y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nacnac-based tridentate ligands containing a pyridyl-methyl and a 2,6-dialkyl-phenylamine (i.e., (2,6-R2-C6H3N═C(Me)CH═C(Me)NH(CH2py); R = Et, {Et(nn)PM}H; R = (i)Pr, {(i)Pr(nn)PM}H) were synthesized by condensation routes. Treatment of M{N(TMS)2}THFn (M = Cr, n = 2; M = Fe, Co, n = 1; TMS = trimethylsilane; THF = tetrahydrofuran) with {(i)Pr(nn)PM}H) afforded {(i)Pr(nn)PM}MN(TMS)2 (1-M(iPr); M = Cr, Fe); {Et(nn)PM}MN(TMS)2 (1-M(Et); M = Fe, Co) was similarly obtained. {R(nn)PM}FeBr (R = (i)Pr, Et; 2-Fe(R)) were prepared from FeBr2 and {R(nn)PM}Li, and alkylated to generate {R(nn)PM}Fe(neo)Pe (R = (i)Pr, Et; 3-Fe(R)). Carbonylation of 3-Fe(R) provided {(i)Pr(nn)PM}Fe(CO(neo)Pe)CO (4-Fe(iPr)), and carbonylations of 1-Fe(R) (R = Et, (i)Pr) and 1-Cr(iPr) induced deamination to afford {R(nn)PI}Fe(CO)2 (R = (i)Pr, 5-Fe(iPr); Et, 5-Fe(Et)), where PI is pyridine-imine, and {κ(2)-N,N-pyrim-pyr}Cr(CO)4 (6-Cr(iPr)), in which the aryl-amide side of the nacnac attacked the incipient PI group. Carbon-carbon bonds were formed at the imine carbon of the {R(nn)PI} ligand. Addition of [{(i)Pr(nn)PI}(2-)](K(+)(THF)x)2 to FeCl3 generated {(i)Pr(nn)CHpy}2Fe2Cl2 (7-Fe(iPr)), and TMSN3 induced the deamination of 1-Fe(Et), but with disproportionation to provide {[Et(nn)CHpy]2}Fe (8-Fe(Et)). Ph2CN2 induced C-C bond formation with 1-Fe(iPr) via its thermal degradation to ultimately afford {(i)Pr(nn)CHpy}2(FeN═CPh2)2 (9-Fe(iPr)). The compounds were examined by X-ray crystallography (1-M(iPr), M = Cr, Fe; 1-Co(Et); 2-Fe(iPr); 4-Fe(iPr); 5-Fe(iPr); 6-Cr(iPr); 7-Fe(iPr); 8-Fe(Et); 9-Fe(iPr)), Mössbauer spectroscopy, and NMR spectroscopy. Structural parameters assessing redox noninnocence are discussed, as are structural and mechanistic consequences of the various electronic environments.
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Affiliation(s)
- Wesley D Morris
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
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71
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Zhang H, Ouyang Z, Liu Y, Zhang Q, Wang L, Deng L. (Aminocarbene)(Divinyltetramethyldisiloxane)Iron(0) Compounds: A Class of Low-Coordinate Iron(0) Reagents. Angew Chem Int Ed Engl 2014; 53:8432-6. [DOI: 10.1002/anie.201404677] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 11/08/2022]
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72
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Zhang H, Ouyang Z, Liu Y, Zhang Q, Wang L, Deng L. (Aminocarbene)(Divinyltetramethyldisiloxane)Iron(0) Compounds: A Class of Low-Coordinate Iron(0) Reagents. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404677] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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73
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Williams VA, Wolczanski PT, Sutter J, Meyer K, Lobkovsky EB, Cundari TR. Iron complexes derived from {nacnac-(CH2py)2}- and {nacnac-(CH2py)(CHpy)}n ligands: stabilization of iron(II) via redox noninnocence. Inorg Chem 2014; 53:4459-74. [PMID: 24762120 DOI: 10.1021/ic5001123] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nacnac-based tetradentate chelates, {nacnac-(CH2py)2}(-) ({nn(PM)2}(-)) and {nacnac-(CH2py)(CHpy)}(n) ({nn(PM)(PI)}(n)) have been investigated in iron complexes. Treatment of Fe{N(TMS)2}2(THF) with {nn(PM)2}H afforded {nn(PM)2}FeN(TMS)2 [1-N(TMS)2], which led to {nn(PM)2}FeCl (1-Cl) from HCl and to {nn(PM)2}FeN3 (1-N3) upon salt metathesis. Dehydroamination of 1-N(TMS)2 was induced by L (L = PMe3, CO) to afford {nn(PM)(PI)}Fe(PMe3)2 [2-(PMe3)2] and {nn(PM)(PI)}FeCO (3-CO). Substitution of 2-(PMe3)2 led to {nn(PM)(PI)}Fe(PMe3)CO [2-(PMe3)CO], and exposure to a vacuum provided {nn(PM)(PI)}Fe(PMe3) (3-PMe3). Metathesis routes to {nn(PM)(PI)}FeL2 (2-L2; L = PMe3, PMe2Ph) and {nn(PM)(PI)}FeL (3-L; L = PMePh2, PPh3) from [{nn(PM)(PI)}(2-)]Li2 and FeBr2(THF)2 in the presence of L proved feasible, and 1e(-) and 2e(-) oxidation of 2-(PMe3)2 afforded 2(+)-(PMe3)2 and 2(2+)-(PMe3)2 salts. Mössbauer spectroscopy, structural studies, and calculational assessments revealed the dominance of iron(II) in both high-spin (1-X) and low-spin (2-L2 and 3-L) environments, and the redox noninnocence (RNI) of {nn(PM)(PI)}(n) [2-L2, 3-L, n = 2-; 2(+)-(PMe3)2, n = 1-; 2(2+)-(PMe3)2, n = 0]. A discussion regarding the utility of RNI in chemical reactivity is proffered.
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Affiliation(s)
- Valerie A Williams
- Baker Laboratory, Department of Chemistry & Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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74
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Di Francesco GN, Gaillard A, Ghiviriga I, Abboud KA, Murray LJ. Modeling Biological Copper Clusters: Synthesis of a Tricopper Complex, and Its Chloride- and Sulfide-Bridged Congeners. Inorg Chem 2014; 53:4647-54. [DOI: 10.1021/ic500333p] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Gianna N. Di Francesco
- Department
of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Aleth Gaillard
- Department
of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Ion Ghiviriga
- Department
of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Khalil A. Abboud
- Department
of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Leslie J. Murray
- Department
of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611-7200, United States
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75
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Saouma CT, Mayer JM. Do Spin State and Spin Density Affect Hydrogen Atom Transfer Reactivity? Chem Sci 2014; 5. [PMID: 24416504 DOI: 10.1039/c3sc52664j] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The prevalence of hydrogen atom transfer (HAT) reactions in chemical and biological systems has prompted much interest in establishing and understanding the underlying factors that enable this reactivity. Arguments have been advanced that the electronic spin state of the abstractor and/or the spin-density at the abstracting atom are critical for HAT reactivity. This is consistent with the intuition derived from introductory organic chemistry courses. Herein we present an alternative view on the role of spin state and spin-density in HAT reactions. After a brief introduction, the second section introduces a new and simple fundamental kinetic analysis, which shows that unpaired spin cannot be the dominant effect. The third section examines published computational studies of HAT reactions, which indicates that the spin state affects these reactions indirectly, primarily via changes in driving force. The essay concludes with a broader view of HAT reactivity, including indirect effects of spin and other properties on reactivity. It is suggested that some of the controversy in this area may arise from the diversity of HAT reactions and their overlap with proton-coupled electron transfer (PCET) reactions.
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Affiliation(s)
- Caroline T Saouma
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, USA
| | - James M Mayer
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, USA
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76
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Olivos Suarez AI, Lyaskovskyy V, Reek JNH, van der Vlugt JI, de Bruin B. Komplexe mit Stickstoffradikalliganden: Einteilung, spektroskopische Eigenschaften, Reaktivität und katalytische Anwendungen. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301487] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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77
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Suarez AIO, Lyaskovskyy V, Reek JNH, van der Vlugt JI, de Bruin B. Complexes with Nitrogen-Centered Radical Ligands: Classification, Spectroscopic Features, Reactivity, and Catalytic Applications. Angew Chem Int Ed Engl 2013; 52:12510-29. [DOI: 10.1002/anie.201301487] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Indexed: 01/07/2023]
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78
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Ruddy AJ, Kelly CM, Crawford SM, Wheaton CA, Sydora OL, Small BL, Stradiotto M, Turculet L. (N-Phosphinoamidinate)Iron Pre-Catalysts for the Room Temperature Hydrosilylation of Carbonyl Compounds with Broad Substrate Scope at Low Loadings. Organometallics 2013. [DOI: 10.1021/om400883u] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Adam J. Ruddy
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Colin M. Kelly
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Sarah M. Crawford
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Craig A. Wheaton
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Orson L. Sydora
- Research and Technology, Chevron Phillips Chemical Company, 1862 Kingwood Drive, Kingwood, Texas 77339, United States
| | - Brooke L. Small
- Research and Technology, Chevron Phillips Chemical Company, 1862 Kingwood Drive, Kingwood, Texas 77339, United States
| | - Mark Stradiotto
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Laura Turculet
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
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79
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Cowley RE, Golder MR, Eckert NA, Al-Afyouni MH, Holland PL. Mechanism of Catalytic Nitrene Transfer Using Iron(I)–Isocyanide Complexes. Organometallics 2013. [DOI: 10.1021/om400379p] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Ryan E. Cowley
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Matthew R. Golder
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Nathan A. Eckert
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Malik H. Al-Afyouni
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Patrick L. Holland
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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80
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Olatunji-Ojo OA, Cundari TR. C–H Activation by Multiply Bonded Complexes with Potentially Noninnocent Ligands: A Computational Study. Inorg Chem 2013; 52:8106-13. [DOI: 10.1021/ic400804x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Olayinka A. Olatunji-Ojo
- Department of Chemistry
and Center for Advanced Scientific
Computing and Modeling (CASCaM), University of North Texas, 1155 Union Circle, #305070 Denton, Texas 76203-5070,
United States
| | - Thomas R. Cundari
- Department of Chemistry
and Center for Advanced Scientific
Computing and Modeling (CASCaM), University of North Texas, 1155 Union Circle, #305070 Denton, Texas 76203-5070,
United States
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81
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Liu Y, Guan X, Wong ELM, Liu P, Huang JS, Che CM. Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations. J Am Chem Soc 2013; 135:7194-204. [PMID: 23634746 DOI: 10.1021/ja3122526] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The 7-coordinate complex [Fe(qpy)(MeCN)2](ClO4)2 (1, qpy = 2,2':6',2″:6″,2''':6''',2''''-quinquepyridine) is a highly active nonheme iron catalyst for intra- and intermolecular amination of C(sp(3))-H bonds. This complex effectively catalyzes the amination of limiting amounts of not only benzylic and allylic C(sp(3))-H bonds of hydrocarbons but also the C(sp(3))-H bonds of cyclic alkanes and cycloalkane/linear alkane moieties in sulfamate esters, such as those derived from menthane and steroids cholane and androstane, using PhI═NR or "PhI(OAc)2 + H2NR" [R = Ts (p-toluenesulfonyl), Ns (p-nitrobenzenesulfonyl)] as nitrogen source, with the amination products isolated in up to 93% yield. Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)](n+) (CX, X = NR, solvent, or anion) are proposed in these amination reactions on the basis of experimental studies including ESI-MS analysis, crossover experiments, Hammett plots, and correlation with C-H bond dissociation energies and with support by DFT calculations. Species consistent with the formulations of [Fe(qpy)(NTs)2](2+) (CNTs) and [Fe(qpy)(NTs)](2+) (C) were detected by high-resolution ESI-MS analysis of the reaction mixture of 1 with PhI═NTs (4 equiv). DFT calculations revealed that the reaction barriers for H-atom abstraction of cyclohexane by the ground state of 7-coordinate CNTs and ground state of C are 15.3 and 14.2 kcal/mol, respectively, in line with the observed high activity of 1 in catalyzing the C-H amination of alkanes under mild conditions.
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Affiliation(s)
- Yungen Liu
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong
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82
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Leeladee P, Jameson GNL, Siegler MA, Kumar D, de Visser SP, Goldberg DP. Generation of a high-valent iron imido corrolazine complex and NR group transfer reactivity. Inorg Chem 2013; 52:4668-82. [PMID: 23527920 DOI: 10.1021/ic400280x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The generation of a new high-valent iron terminal imido complex prepared with a corrolazine macrocycle is reported. The reaction of [Fe(III)(TBP8Cz)] (TBP8Cz = octakis(4-tert-butylphenyl)corrolazinato) with the commercially available chloramine-T (Na(+)TsNCl(-)) leads to oxidative N-tosyl transfer to afford [Fe(IV)(TBP8Cz(+•))(NTs)] in dichloromethane/acetonitrile at room temperature. This complex was characterized by UV-vis, Mössbauer (δ = -0.05 mm s(-1), ΔE(Q) = 2.94 mm s(-1)), and EPR (X-band (15 K), g = 2.10, 2.00) spectroscopies, and together with reactivity patterns and DFT calculations has been established as an iron(IV) species antiferromagnetically coupled with a Cz-π-cation-radical (S(total) = 1/2 ground state). Reactivity studies with triphenylphosphine as substrate show that [Fe(IV)(TBP8Cz(+•))(NTs)] is an efficient NTs transfer agent, affording the phospharane product Ph3P═NTs under both stoichiometric and catalytic conditions. Kinetic analysis of this reaction supports a bimolecular NTs transfer mechanism with rate constant of 70(15) M(-1) s(-1). These data indicate that [Fe(IV)(TBP8Cz(+•))(NTs)] reacts about 100 times faster than analogous Mn terminal arylimido corrole analogues. It was found that two products crystallize from the same reaction mixture of Fe(III)(TBP8Cz) + chloramine-T + PPh3, [Fe(IV)(TBP8Cz)(NPPh3)] and [Fe(III)(TBP8Cz)(OPPh3)], which were definitively characterized by X-ray crystallography. The sequential production of Ph3P═NTs, Ph3P═NH, and Ph3P═O was observed by (31)P NMR spectroscopy and led to a proposed mechanism that accounts for all of the observed products. The latter Fe(III) complex was then rationally synthesized and structurally characterized from Fe(III)(TBP8Cz) and OPPh3, providing an important benchmark compound for spectroscopic studies. A combination of Mössbauer and EPR spectroscopies led to the characterization of both intermediate spin (S = 3/2 and low spin (S = 1/2) Fe(III) corrolazines, as well as a formally Fe(IV) corrolazine which may also be described by its valence tautomer Fe(III)(Cz(+•)).
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Affiliation(s)
- Pannee Leeladee
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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83
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Xu X, Jia J, Sun H, Liu Y, Xu W, Shi Y, Zhang D, Li X. Selective activation of C–F and C–H bonds with iron complexes, the relevant mechanism study by DFT calculations and study on the chemical properties of hydrido iron complex. Dalton Trans 2013; 42:3417-28. [DOI: 10.1039/c2dt31795h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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