Combined Experimental and Computational Studies on the Nature of Aromatic C-H Activation by Octahedral Ruthenium(II) Complexes: Evidence for σ-Bond Metathesis from Hammett Studies

Description:

Article discussing combined experimental and computational studies on the nature of aromatic C-H activation by octahedral ruthenium(II) complexes of the type TpRu(L)(NCMe)R [Tp = hydridotris(pyrazolyl)borate; R = alkyl or aryl; L = CO or PMe3].

Creator(s):
Creation Date: November 27, 2007
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
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Creator (Author):
DeYonker, Nathan J.

University of North Texas

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Foley, Nicholas A.

North Carolina State University

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Cundari, Thomas R., 1964-

University of North Texas

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Gunnoe, T. Brent

North Carolina State University

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Petersen, Jeffrey L.

West Virginia University

Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, DC]
Date(s):
  • Creation: November 27, 2007
Description:

Article discussing combined experimental and computational studies on the nature of aromatic C-H activation by octahedral ruthenium(II) complexes of the type TpRu(L)(NCMe)R [Tp = hydridotris(pyrazolyl)borate; R = alkyl or aryl; L = CO or PMe3].

Degree:
Department: Chemistry
Note:

Reprinted with permission from Organometallics. Copyright 2007 American Chemical Society.

Note:

Abstract: Octahedral ruthenium complexes of the type TpRu(L)(NCMe)R [Tp = hydridotris(pyrazolyl)borate; R = alkyl or aryl; L = CO or PMe3] have been shown previously to initiate the C-H activation of aromatic substrates. In order to probe the nature of the C-H activation step, reaction rates have been theoretically obtained for the conversion of TpRu(L)(ƞ2-C,C-C6H5X)Me to TpRu(L)(ρ-C6H4X) and CH4 where X is varied among Br, Cl, CN, F, H, NH2, NO2, and OMe. A linear Hammett correlation is calculated with a positive ρ value of 2.6 for L = CO and 3.2 for L = PMe3. Calculated kinetic data for the aromatic C-H activations indicate that an electrophilic aromatic substitution mechanism is unlikely. While experiments cannot fully replicate the entire range of calculated Hammett plots, reactivity trends are consistent with the calculations that suggest activation barriers to overall metal-mediated arene C-H bond cleavage are reduced by the presence of electron-withdrawing groups in the position para to the site of activation. Previous mechanistic studies, as well as the structure and imaginary vibrational modes of the present transition states, validate that the C-H activation for this family of TpRu complexes occurs through a σ-bond metathesis-type pathway.

Physical Description:

8 p.

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Subject(s):
Keyword(s): octahedral ruthenium | Hammett correlatioin | arene C-H bonds
Source: Organometallics, 2007, Washington DC: American Chemical Society, pp. 6604-6611
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/om7009057 |
  • ARK: ark:/67531/metadc83332
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Organometallics
Volume: 26
Issue: 26
Page Start: 6604
Page End: 6611
Peer Reviewed: Yes