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Mechanistic Analysis of Hydroarylation Catalysts

Oxgaard, Jonas and Periana, Roy A. and Goddard, William A., III (2004) Mechanistic Analysis of Hydroarylation Catalysts. Journal of the American Chemical Society, 126 (37). pp. 11658-11665. ISSN 0002-7863. doi:10.1021/ja048841j. https://resolver.caltech.edu/CaltechAUTHORS:20170419-154841546

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Abstract

Recently, two organometallic systems ([Ir(μ-acac-O)(acac-O,O)(acac-C^3)]_2 and (Tp)Ru(CO)(Ph)(NCCH_3)) have been discovered that catalyze hydroarylation of unactivated olefins. Herein, we use density functional theory (B3LYP) to study the factors underlying this class of catalysts. In addition, we calculate the key steps for Rh, Pd, Os, and Pt with similar ligand sets. We previously showed there to be two key steps in the process:  (i) insertion of a phenyl into the π bond of a coordinating olefin, and (ii) C−H activation/hydrogen transfer of an unactivated benzene. An important discovery in these studies is that the barriers for these two steps are inversely correlated, complicating optimization of the overall process. However, herein we elucidate the causes of this inverse correlation, laying the foundation for the rational design of improved catalysts. Both steps are directly influenced by the accessibility of the higher 2-electron oxidation state, M^n → M^(n+2). Systems with an easily accessible M^(n+2) state activate C−H bonds easily but suffer from high energy insertions due to significant back-bonding. Conversely, systems without an easily accessible M^(n+2) state have no debilitating back-bonding which makes insertion steps facile, but cannot effectively activate the C−H bond (leading instead to polymerization). The relationship between accessibility of the M^(n+2) state and the amount of back-bonding in the coordinating olefin can be visualized by inspecting the hybridization of the coordinating olefin. Furthermore, we find a linear relation between this hybridization and the barrier to insertion. On the basis of these concepts, we suggest some modifications of the σ framework expected to improve the rates beyond this linear correlation.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja048841jDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja048841jPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ja048841jPublisherSupporting Information
ORCID:
AuthorORCID
Periana, Roy A.0000-0001-7838-257X
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2004 American Chemical Society. Received March 1, 2004. Publication Date (Web): August 27, 2004. We gratefully acknowledge financial support of this research by the ChevronTexaco Energy Research and Technology Co., and we thank Dr. Michael Driver and Dr. William Schinski of ChevronTexaco for helpful discussions. We also wish to thank Robert Nielsen, Guarav Bhalla, and Dr. Xiang Yang Liu for suggestions and insights.
Funders:
Funding AgencyGrant Number
Chevron-Texaco Energy Research and Technology Co.UNSPECIFIED
Issue or Number:37
DOI:10.1021/ja048841j
Record Number:CaltechAUTHORS:20170419-154841546
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170419-154841546
Official Citation:Mechanistic Analysis of Hydroarylation Catalysts Jonas Oxgaard, Roy A. Periana, and William A. Goddard, III Journal of the American Chemical Society 2004 126 (37), 11658-11665 DOI: 10.1021/ja048841j
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76724
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Apr 2017 22:57
Last Modified:15 Nov 2021 17:02

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