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Wills AG, Charvet S, Battilocchio C, Scarborough CC, Wheelhouse KMP, Poole DL, Carson N, Vantourout JC. High-Throughput Electrochemistry: State of the Art, Challenges, and Perspective. Org Process Res Dev 2021. [DOI: 10.1021/acs.oprd.1c00167] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Alfie G. Wills
- Medicinal Chemistry, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
- Department of Pure & Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
| | - Sylvain Charvet
- Univ Lyon, Université Lyon 1, CNRS, INSA, CPE-Lyon, ICBMS, UMR 5246, Bâtiment LEDERER, 1 rue Victor Grignard, 69622 Villeurbanne Cedex, France
| | - Claudio Battilocchio
- Research Chemistry, Syngenta Crop Protection, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | | | - Katherine M. P. Wheelhouse
- Chemical Development, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Darren L. Poole
- Medicinal Chemistry, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Nessa Carson
- Syngenta Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom
| | - Julien C. Vantourout
- Univ Lyon, Université Lyon 1, CNRS, INSA, CPE-Lyon, ICBMS, UMR 5246, Bâtiment LEDERER, 1 rue Victor Grignard, 69622 Villeurbanne Cedex, France
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2
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Wang P, Saber MR, VanNatta PE, Yap GPA, Popescu CV, Scarborough CC, Kieber-Emmons MT, Dunbar KR, Riordan CG. Molecular and Electronic Structures and Single-Molecule Magnet Behavior of Tris(thioether)-Iron Complexes Containing Redox-Active α-Diimine Ligands. Inorg Chem 2021; 60:6480-6491. [PMID: 33840189 DOI: 10.1021/acs.inorgchem.1c00214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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
Incorporating radical ligands into metal complexes is one of the emerging trends in the design of single-molecule magnets (SMMs). While significant effort has been expended to generate multinuclear transition metal-based SMMs with bridging radical ligands, less attention has been paid to mononuclear transition metal-radical SMMs. Herein, we describe the first α-diiminato radical-containing mononuclear transition metal SMM, namely, [κ2-PhTttBu]Fe(AdNCHCHNAd) (1), and its analogue [κ2-PhTttBu]Fe(CyNCHCHNCy) (2) (PhTttBu = phenyltris(tert-butylthiomethyl)borate, Ad = adamantyl, and Cy = cyclohexyl). 1 and 2 feature nearly identical geometric and electronic structures, as shown by X-ray crystallography and electronic absorption spectroscopy. A more detailed description of the electronic structure of 1 was obtained through EPR and Mössbauer spectroscopies, SQUID magnetometry, and DFT, TD-DFT, and CAS calculations. 1 and 2 are best described as high-spin iron(II) complexes with antiferromagnetically coupled α-diiminato radical ligands. A strong magnetic exchange coupling between the iron(II) ion and the ligand radical was confirmed in 1, with an estimated coupling constant J < -250 cm-1 (J = -657 cm-1, DFT). Calibrated CAS calculations revealed that the ground-state Fe(II)-α-diiminato radical configuration has significant ionic contributions, which are weighted specifically toward the Fe(I)-neutral α-diimine species. Experimental data and theoretical calculations also suggest that 1 possesses an easy-axis anisotropy, with an axial zero-field splitting parameter D in the range from -4 to-1 cm-1. Finally, dynamic magnetic studies show that 1 exhibits slow magnetic relaxation behavior with an energy barrier close to the theoretical maximum, 2|D|. These results demonstrate that incorporating strongly coupled α-diiminato radicals into mononuclear transition metal complexes can be an effective strategy to prepare SMMs.
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Affiliation(s)
- Peng Wang
- Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Mohamed R Saber
- Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, United States.,Department of Chemistry, Fayoum University, Fayoum 63514, Egypt
| | - Peter E VanNatta
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - Glenn P A Yap
- Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Codrina V Popescu
- Department of Chemistry, University of Saint Thomas, 2115 Summit Avenue, Saint Paul, Minnesota 55105, United States
| | - Christopher C Scarborough
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States.,Syngenta Crop Protection AG, Schaffhauserstrasse, CH-4332 Stein, Switzerland
| | | | - Kim R Dunbar
- Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, United States
| | - Charles G Riordan
- Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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3
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Affiliation(s)
- Matthias Lehmann
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332, Stein, Switzerland
| | | | - Edouard Godineau
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332, Stein, Switzerland
| | - Claudio Battilocchio
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332, Stein, Switzerland
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4
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Pickel TC, Karahalis GJ, Buru CT, Bacsa J, Scarborough CC. Synthesis of Previously Inaccessible Derivatives of 1,4,7-Tri
-R-1,4,7-Triazacyclononane, Including Chiral Examples, and a Rapid Synthesis of the HCl Salts of H3
tacn and H4
dtne. European J Org Chem 2018. [DOI: 10.1002/ejoc.201801323] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Thomas C. Pickel
- Department of Chemistry; Emory University; 1515 Dickey Dr. 30322 Atlanta GA USA
| | | | - Cassandra T. Buru
- Department of Chemistry; Emory University; 1515 Dickey Dr. 30322 Atlanta GA USA
| | - John Bacsa
- Department of Chemistry; Emory University; 1515 Dickey Dr. 30322 Atlanta GA USA
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5
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Affiliation(s)
- Christian M. Wallen
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - John Bacsa
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
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6
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Wallen CM, Palatinus L, Bacsa J, Scarborough CC. Hydrogen Peroxide Coordination to Cobalt(II) Facilitated by Second-Sphere Hydrogen Bonding. Angew Chem Int Ed Engl 2016; 55:11902-6. [PMID: 27560462 DOI: 10.1002/anie.201606561] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Indexed: 11/11/2022]
Abstract
M(H2 O2 ) adducts have been postulated as intermediates in biological and industrial processes; however, only one observable M(H2 O2 ) adduct has been reported, where M is redox-inactive zinc. Herein, direct solution-phase detection of an M(H2 O2 ) adduct with a redox-active metal, cobalt(II), is described. This Co(II) (H2 O2 ) compound is made observable by incorporating second-sphere hydrogen-bonding interactions between bound H2 O2 and the supporting ligand, a trianionic trisulfonamido ligand. Thermodynamics of H2 O2 binding and decay kinetics of the Co(II) (H2 O2 ) species are described, as well as the reaction of this Co(II) (H2 O2 ) species with Group 2 cations.
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Affiliation(s)
- Christian M Wallen
- Department of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, GA, 30322, USA
| | - Lukáš Palatinus
- Department of Structure Analysis, Institute of Physics of the AS CR, Prague, Czechia
| | - John Bacsa
- Department of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, GA, 30322, USA
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7
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Karahalis GJ, Thangavel A, Chica B, Bacsa J, Dyer RB, Scarborough CC. Synthesis and Catalytic Reactivity of a Dicopper(II) μ-η2:η2-Peroxo Species Supported by 1,4,7-Tri-tert-butyl-1,4,7-triazacyclononane. Inorg Chem 2016; 55:1102-7. [DOI: 10.1021/acs.inorgchem.5b02205] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [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)
- Gregory J. Karahalis
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Arumugam Thangavel
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Bryant Chica
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - John Bacsa
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - R. Brian Dyer
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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8
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Abstract
CoII complexes bearing sulfonamido ligands derived from tris(2-aminoethyl)amine (H6tren) assemble into complex architectures in the presence of Group II ions through interactions between the Group II ion and the sulfonyl oxygens.
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Affiliation(s)
| | | | - John Bacsa
- Department of Chemistry
- Emory University
- Atlanta
- USA
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9
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Abstract
Metal(H2O2) complexes have been implicated in kinetic and computational studies but have never been observed. Accordingly, H2O2 has been described as a very weak ligand. We report the first metal(H2O2) adduct, which is made possible by incorporating intramolecular hydrogen-bonding interactions with bound H2O2. This Zn(II)(H2O2) complex decays in solution by a second-order process that is slow enough to enable characterization of this species by X-ray crystallography. This report speaks to the intermediacy of metal(H2O2) adducts in chemistry and biology and opens the door to exploration of these species in oxidation catalysis.
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Affiliation(s)
- Christian M Wallen
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - John Bacsa
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Christopher C Scarborough
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
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10
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Thangavel A, Wieliczko M, Bacsa J, Scarborough CC. 1,4,7-Triazacyclononane Ligands Bearing Tertiary Alkyl Nitrogen Substituents. Inorg Chem 2013; 52:13282-7. [PMID: 24187908 DOI: 10.1021/ic402626p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Arumugam Thangavel
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Marika Wieliczko
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - John Bacsa
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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11
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Rodriguez MM, Stubbert BD, Scarborough CC, Brennessel WW, Bill E, Holland PL. Isolation and characterization of stable iron(I) sulfide complexes. Angew Chem Int Ed Engl 2012; 51:8247-50. [PMID: 22821816 PMCID: PMC3970908 DOI: 10.1002/anie.201202211] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Indexed: 11/11/2022]
Affiliation(s)
| | - Bryan D. Stubbert
- Department of Chemistry University of Rochester Rochester, NY 14627 (USA)
| | | | | | - Eckhard Bill
- Max-Planck-Institut für Bioanorganische Chemie 45470 Mülheim an der Ruhr (Germany)
| | - Patrick L. Holland
- Department of Chemistry University of Rochester Rochester, NY 14627 (USA)
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12
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Rodriguez MM, Stubbert BD, Scarborough CC, Brennessel WW, Bill E, Holland PL. Isolation and Characterization of Stable Iron(I) Sulfide Complexes. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202211] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Affiliation(s)
- Christopher C. Scarborough
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstraße
34-36, D-45470 Mülheim an der Ruhr, Germany
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta Georgia
30322, United States
| | - Stephen Sproules
- EPSRC
National UK EPR Facility
and Service, Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Christian J. Doonan
- School of Chemistry and Physics, The University of Adelaide, SA 5005, Australia
| | - Karl S. Hagen
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta Georgia
30322, United States
| | - Thomas Weyhermüller
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstraße
34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Karl Wieghardt
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstraße
34-36, D-45470 Mülheim an der Ruhr, Germany
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14
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England J, Scarborough CC, Weyhermüller T, Sproules S, Wieghardt K. Electronic Structures of the Electron Transfer Series [M(bpy)3]n, [M(tpy)2]n, and [Fe(tbpy)3]n(M = Fe, Ru;n= 3+, 2+, 1+, 0, 1-): A Mössbauer Spectroscopic and DFT Study. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201200232] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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Scarborough CC, Lancaster KM, DeBeer S, Weyhermüller T, Sproules S, Wieghardt K. Experimental Fingerprints for Redox-Active Terpyridine in [Cr(tpy)2](PF6)n (n = 3–0), and the Remarkable Electronic Structure of [Cr(tpy)2]1–. Inorg Chem 2012; 51:3718-32. [DOI: 10.1021/ic2027219] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Christopher C. Scarborough
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta Georgia
30322, United States
| | - Kyle M. Lancaster
- Department
of Chemistry and Chemical
Biology, Cornell University, Ithaca, New
York 14853, United States
| | - Serena DeBeer
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry and Chemical
Biology, Cornell University, Ithaca, New
York 14853, United States
| | - Thomas Weyhermüller
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
| | - Stephen Sproules
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
- EPSRC National UK EPR Facility
and Service, Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
| | - Karl Wieghardt
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
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16
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Chiang KP, Scarborough CC, Horitani M, Lees NS, Ding K, Dugan TR, Brennessel WW, Bill E, Hoffman BM, Holland PL. Characterization of the FeH Bond in a Three-Coordinate Terminal Hydride Complex of Iron(I). Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201109204] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Chiang KP, Scarborough CC, Horitani M, Lees NS, Ding K, Dugan TR, Brennessel WW, Bill E, Hoffman BM, Holland PL. Characterization of the Fe-H bond in a three-coordinate terminal hydride complex of iron(I). Angew Chem Int Ed Engl 2012; 51:3658-62. [PMID: 22374689 DOI: 10.1002/anie.201109204] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Indexed: 11/11/2022]
Affiliation(s)
- Karen P Chiang
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
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18
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Scarborough CC, Sproules S, Weyhermüller T, DeBeer S, Wieghardt K. Electronic and Molecular Structures of the Members of the Electron Transfer Series [Cr(tbpy)3]n (n = 3+, 2+, 1+, 0): An X-ray Absorption Spectroscopic and Density Functional Theoretical Study. Inorg Chem 2011; 50:12446-62. [DOI: 10.1021/ic201123x] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [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)
- Christopher C. Scarborough
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
| | - Stephen Sproules
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
| | - Thomas Weyhermüller
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
- Department of Chemistry and
Chemical Biology, Cornell University, Ithaca,
New York 14853, United States
| | - Karl Wieghardt
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
D-45470 Mülheim an der Ruhr, Germany
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19
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Scarborough CC, Wieghardt K. Electronic structure of 2,2'-bipyridine organotransition-metal complexes. Establishing the ligand oxidation level by density functional theoretical calculations. Inorg Chem 2011; 50:9773-93. [PMID: 21678919 DOI: 10.1021/ic2005419] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A density functional theoretical (DFT) study (B3LYP) has been carried out on 20 organometallic complexes containing η(5)- and/or η(3)-coordinated cyclopentadienyl anions (Cp(-)) and 2,2'-bipyridine (bpy) ligand(s) at varying oxidation levels, i.e., as the neutral ligand (bpy(0)), as the π-radical monoanion (bpy(•-))(-), or as the diamagnetic dianion (bpy(2-))(2-). The molecular and electronic structures of these species in their ground states and, in some cases, their first excited states have been calculated using broken-symmetry methodology. The results are compared with experimental structural and spectroscopic data (where available) in order to validate the DFT computational approach. The following electron-transfer series and complexes have been studied: [(Cp)(2)V(bpy)](0,+,2+) (1-3), [(Cp)(2)Ti(bpy)](-,0,+,2+) (4-7), [(Cp)(2)Ti(biquinoline)](0,+) (8 and 9), [(Cp*)(2)Ti(bpy)](0) (10) (Cp* = pentamethylcyclopentadienyl anion), [Cp*Co(bpy)](0,+) (11 and 12), [Cp*Co(bpy)Cl](+,0) (13 and 14), [Fe(toluene)(bpy)](0) (15), [Cp*Ru(bpy)](-) (16), [(Cp)(2)Zr(bpy)](0) (17), and [Mn(CO)(3)(bpy)](-) (18). In order to test the predictive power of our computations, we have also calculated the molecular and electronic structures of two complexes, A and B, namely, the diamagnetic dimer [Cp*Sc(bpy)(μ-Cl)](2) (A) and the paramagnetic (at 25 °C) mononuclear species [(η(5)-C(5)H(4)(CH(2))(2)N(CH(3))(2))Sc((m)bpy)(2)] (B). The crystallographically observed intramolecular π-π interaction of two N,N'-coordinated π-radical anions in A leading to an S = 0 ground state is reliably reproduced. Similarly, the small singlet-triplet gap of ~600 cm(-1) between two antiferromagnetically coupled (bpy(•-))(-) ligands in B, two ferromagnetically coupled radical anions in the triplet excited state of B, and the structures of A and B is reproduced. Therefore, we are confident that we can present computationally obtained, detailed electronic structures for complexes 1-18. We show that N,N'-coordinated neutral bpy(0) ligands behave as very weak π acceptors (if at all), whereas the (bpy(2-))(2-) dianions are strong π-donor ligands.
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Affiliation(s)
- Christopher C Scarborough
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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20
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Scarborough CC, Bergant A, Sazama GT, Guzei IA, Spencer LC, Stahl SS. Synthesis of Pd Complexes Bearing an Enantiomerically-Resolved Seven-Membered N-Heterocyclic Carbene Ligands and Initial Studies of their Use in Asymmetric Wacker-Type Oxidative Cyclization Reactions. Tetrahedron 2009; 65:5084-5092. [PMID: 20161255 DOI: 10.1016/j.tet.2009.04.072] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The development of enantiomerically-resolved, axially-chiral seven-membered N-heterocyclic carbene ((7)NHC) ligands for palladium is described. These (7)NHC ligands are derived from enatiomerically pure 2,2'-diamino-6,6'-dimethylbiphenyl, which is transformed via a synthetic sequence consisting of ortho-arylation, N-alkylation, and cyclization to afford seven-membered-ring amidinium salts. Synthesis of the 7-membered amidinium salts benefits from microwave irradiation, and in-situ metalation of the amidinium salts yields (7)NHC-Pd(II) complexes. The chiral (7)NHC-Pd complexes were examined as chiral catalysts under aerobic conditions in two intramolecular oxidative amination reactions of alkenes. In one case, enantioselectivities up to 63% e.e. were obtained, while the other substrate underwent cyclization to afford essentially racemic products. The catalytic data compare favorably to results obtained with a Pd(II) catalyst bearing a chiral five-membered-ring NHC ligand and, thereby, highlight the potential significance of this new class of chiral NHC ligands.
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21
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Scarborough CC, McDonald RI, Hartmann C, Sazama GT, Bergant A, Stahl SS. Steric modulation of chiral biaryl diamines via Pd-catalyzed directed C-H arylation. J Org Chem 2009; 74:2613-5. [PMID: 19219972 DOI: 10.1021/jo802632v] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [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
Palladium-catalyzed directed arylation of 2,2'-diacetamidobiaryls with aryl iodides provides efficient access to chiral ortho-substituted biaryl diamines. Aryl iodides with para- and meta-substituents are tolerated. Deprotection of the acetyl groups under basic conditions furnishes the free diamines, which should find broad utility in asymmetric catalysis.
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Abstract
A chiral seven-membered N-heterocyclic carbene (NHC) has been synthesized from its phenol adduct (NHC-HOPh) by a novel base-induced alpha-elimination method, and its donor strength has been determined from the IR stretching frequencies of the NHC-Rh(CO)(2)Cl complex.
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23
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Kotov V, Scarborough CC, Stahl SS. Palladium-catalyzed aerobic oxidative amination of alkenes: development of intra- and intermolecular aza-Wacker reactions. Inorg Chem 2007; 46:1910-23. [PMID: 17348722 DOI: 10.1021/ic061997v] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.9] [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: 11/28/2022]
Abstract
Palladium-catalyzed methods for the aerobic oxidative coupling of alkenes and oxygen nucleophiles (e.g., water and carboxylic acids) have been known for nearly 50 years. The present account summarizes our development of analogous aerobic oxidative amination reactions, including the first intermolecular aza-Wacker reactions compatible with the use of unactivated alkenes. The reactions are initiated by intra- or intermolecular aminopalladation of the alkene. The resulting alkylpalladium(II) intermediate generally undergoes beta-hydride elimination to produce enamides or allylic amide products, but in certain cases, the Pd-C bond can be trapped to achieve 1,2-difunctionalization of the alkene, including carboamination and aminoacetoxylation. Mechanistic studies have provided a variety of fundamental insights into the reactions, including the effect of ancillary ligands on palladium catalysts, the origin of the Brønsted-base-induced switch in regioselectivity in the oxidative amination of styrene, and evidence that both cis- and trans-aminopalladations of alkenes are possible. Overall, these reactions highlight the potential utility of an "organometallic oxidase" strategy for the selective aerobic oxidation of organic molecules.
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Affiliation(s)
- Vasily Kotov
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
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Scarborough CC, Stahl SS. Synthesis of Pyrrolidines via Palladium(II)-Catalyzed Aerobic Oxidative Carboamination of Butyl Vinyl Ether and Styrenes with Allyl Tosylamides. Org Lett 2006; 8:3251-4. [PMID: 16836378 DOI: 10.1021/ol061057e] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [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: 11/30/2022]
Abstract
[Structure: see text] Palladium(II) catalyzes the oxidative coupling of allyl tosylamides with butyl vinyl ether and various styrene derivatives to produce 2,4-substituted pyrrolidine products at room temperature. Molecular oxygen together with a copper(II) cocatalyst mediates reoxidation of the palladium catalyst. The reactions with styrene substrates can be performed in an open flask with ambient air as the source of O2. Several nontraditional cocatalysts, including catechol, cyclooctadiene, and methyl acrylate, have a beneficial effect on the reactions.
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Scarborough CC, Grady MJW, Guzei IA, Gandhi BA, Bunel EE, Stahl SS. PdII Complexes Possessing a Seven-Membered N-Heterocyclic Carbene Ligand. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200501522] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Scarborough CC, Grady MJW, Guzei IA, Gandhi BA, Bunel EE, Stahl SS. PdII Complexes Possessing a Seven-Membered N-Heterocyclic Carbene Ligand. Angew Chem Int Ed Engl 2005; 44:5269-72. [PMID: 16035026 DOI: 10.1002/anie.200501522] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Scarborough CC. Selecting pension plans. Hospitals 1973; 47:96 passim. [PMID: 4783763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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