Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron (III) Complex Metadata
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- Main Title Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron (III) Complex
Author: Cowley, Ryan E.Creator Type: PersonalCreator Info: University of Rochester
Author: Eckert, Nathan A.Creator Type: PersonalCreator Info: University of Rochester
Author: Vaddadi, SridharCreator Type: PersonalCreator Info: University of North Texas
Author: Figg, Travis M.Creator Type: PersonalCreator Info: University of North Texas
Author: Cundari, Thomas R., 1964-Creator Type: PersonalCreator Info: University of North Texas
Author: Holland, Patrick L.Creator Type: PersonalCreator Info: University of Rochester
Name: American Chemical SocietyPlace of Publication: [Washington, D.C.]
- Creation: 2011-05-12
- Content Description: This article discusses a mechanistic study of hydrogen atom transfer by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl).
- Physical Description: 16 p.
- Keyword: hydrogen atom transfers
- Keyword: iron-imido complexes
- Keyword: kinetic isotopes
- Keyword: ligands
- Journal: Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 9796-9811
- Publication Title: Journal of the American Chemical Society
- Volume: 133
- Issue: 25
- Page Start: 9796
- Page End: 9811
- Peer Reviewed: True
Name: UNT Scholarly WorksCode: UNTSW
Name: UNT College of Arts and SciencesCode: UNTCAS
- Rights Access: public
- DOI: 10.1021/ja2005303
- Archival Resource Key: ark:/67531/metadc107786
- Academic Department: Chemistry
- Academic Department: Center for Advanced Scientific Computing and Modeling
- Display Note: Reprinted with permission from the Journal of the American Chemical Society. Copyright 2011 American Chemical Society.
- Display Note: Abstract: In the literature, iron-oxo complexes have been isolated and their hydrogen atom transfer (HAT) reactions have been studied in detail. Iron-imido complexes have been isolated more recently, and the community needs experimental evaluations of the mechanism of HAT from late-metal imido species. The authors report a mechanistic study of HAT by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl). HAT is preceded by binding of tert-butylpyridine (ᵗBupy) to form a reactive four-coordinate intermediate LᴹᵉFe(NAd)(ᵗBupy), as shown by equilibrium and kinetic studies. In the HAT step, very large substrate H/D kinetic isotope effects around 100 are consistent with C-H bond cleavage. The elementary HAT rate constant is increased by electron-donating groups on the pyridine additive, and by a more polar medium. When combined with the faster rate of HAT from indene versus cyclohexadiene, this trend is consistent with H⁺ transfer character in the HAT transition state. The increase in HAT rate in the presence of ᵗBupy may be explained by a combination of electronic (weaker Fe=N π-bonding) and thermodynamic (more exothermic HAT) effects. Most importantly, HAT by these imido complexes has a strong dependence on the size of the hydrocarbon substrate. This selectivity comes from steric hindrance by the spectator ligands, a strategy that has promise for controlling the regioselectivity of these C-H bond activation reactions.