Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes Metadata
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- Main Title Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes
Author: McKeown, Bradley A.Creator Type: PersonalCreator Info: University of Virginia
Author: Gonzalez, Hector EmanuelCreator Type: PersonalCreator Info: University of North Texas
Author: Friedfeld, Max R.Creator Type: PersonalCreator Info: University of Virginia
Author: Gunnoe, T. BrentCreator Type: PersonalCreator Info: University of Virginia
Author: Cundari, Thomas R., 1964-Creator Type: PersonalCreator Info: University of North Texas
Author: Sabat, MichalCreator Type: PersonalCreator Info: University of Virginia
Name: American Chemical SocietyPlace of Publication: [Washington, DC]
- Creation: 2011-11-08
- Content Description: This article discusses mechanistic studies of ethylene hydrophenylation catalyzed by bipyridyl Pt(II) complexes.
- Physical Description: 22 p.
- Keyword: ethylene
- Keyword: ethylbenzene
- Keyword: hydrophenylation
- Keyword: catalytic reactions
- Journal: Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 19131-19152
- Publication Title: Journal of the American Chemical Society
- Volume: 133
- Issue: 47
- Page Start: 19131
- Page End: 19152
- Peer Reviewed: True
Name: UNT Scholarly WorksCode: UNTSW
Name: UNT College of Arts and SciencesCode: UNTCAS
- Rights Access: public
- DOI: 10.1021/ja206064v
- Archival Resource Key: ark:/67531/metadc107788
- 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: Cationic platinum (II) complexes [(ᵗbpy)Pt(Ph)-(L)]⁺[ᵗbpy=4,4'-di-tert-butyl-2,2'-bipyridyl; L = THF, NC₅F₅, or NCMe] catalyze the hydrophenylation of ethylene to generate ethylbenzene and isomers of diethylbenzene. Using ethylene as the limiting reagent, an 89% yield of alkylarene products is achieved after 4 h at 120 ˚C. Catalyst efficiency for ethylene hydrophenylation is diminished only slightly under aerobic conditions. Mechanistic studies support a reaction pathway that involves ethylene coordination to Pt(II), insertion of ethylene into the Pt-phenyl bond, and subsequent metal-mediated benzene C-H activation. Studies of stoichiometric benzene (C₆H₆ or C₆D₆) C-H/C-D activation by [(ᵗbpy)Pt(Ph-dn)-(THF)]⁺ (n = 0 or 5) indicate a kʜ/kᴅ = 1.4(1), while comparative rates of ethylene hydrophenylation using C₆H₆ and C₆D₆ reveal kʜ/kᴅ = 1.8(4) for the overall catalytic reaction. DFT calculations suggest that the transition state for benzene C-H activation is the highest energy species along the catalytic cycle. In CD₂Cl₂, [(ᵗbpy)Pt(Ph)(THF)][BAr'₄] [Ar' = 3,5-bis(trifluoromethyl)phenyl] reacts with ethylene to generate [(ᵗbpy)Pt(CH₂CH₂Ph)(ɳ²-C₂H₄)][BAr'₄] with kobs = 1.05(4) x 10⁻³ s⁻¹ (23 ˚C, [C₂H₄] = 0.10(1) M). In the catalytic hydrophenylation of ethylene, substantial amounts of diethylbenzenes are produced, and experimental studies suggest that the selectivity for the monoalkylated arene is diminished due to a second aromatic C-H activation competing with ethylbenzene dissociation.