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Pd-Mediated Activation of Molecular Oxygen: Pd(0) versus Direct Insertion

Keith, Jason M. and Goddard, William A., III and Oxgaard, Jonas (2007) Pd-Mediated Activation of Molecular Oxygen: Pd(0) versus Direct Insertion. Journal of the American Chemical Society, 129 (34). pp. 10361-10369. ISSN 0002-7863. https://resolver.caltech.edu/CaltechAUTHORS:20170424-141751189

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Abstract

In developing environmentally benign chemistries, it is most important to use dioxygen directly in lieu of toxic and/or corrosive stoichiometric oxidants. Unfortunately, for many processes such direct oxidations have not yet become practical. To help develop such processes, we elucidate here the mechanism for the reaction of molecular oxygen with toluene-solvated palladium−hydride complex using quantum mechanics (B3LYP/LACVP** with the PBF polarizable continuum solvent model) for Pd^(II-)((−)sparteine)(H)(Cl) in the presence of base, specifically focusing on the pathways proceeding through Pd^0. The lowest barrier Pd^0 pathway proceeds through a rate-determining base-assisted deprotonation of the palladium, followed by the association of molecular oxygen and the subsequent loss of chloride, forming the corresponding η^2-peroxo−palladium complex. We also examine the spin transition and the completion of the reaction to form PdCl_2 and H_2O_2. Together with our previously published Pd−H/O_2 direct insertion mechanism, these reports provide a complete mapping of the possible pathways for reoxidation of palladium hydride with molecular oxygen. For this particular system, we conclude that direct insertion is preferred (ΔΔH⧧ = 6.2 kcal/mol, ΔΔG⧧ = 7.5 kcal/mol) and trace this preference to the bidentate character of sparteine and the lack of π-accepting ligands. Suggestions are included for how this preference can be switched.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja070462dDOIArticle
http://pubs.acs.org/doi/suppl/10.1021/ja070462dPublisherSupporting Information
ORCID:
AuthorORCID
Keith, Jason M.0000-0002-5292-397X
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2007 American Chemical Society. Received January 22, 2007. Publication Date (Web): August 3, 2007. J.M.K. thanks the National Science Foundation for financial support. This research was partly funded by the DOE (DE-PS36-06GO96018 and DE-PS36-03GO93015), NSF (CTS-0608889) and Chevron Corp. The facilities used were funded by Grants from ARO-DURIP, ONR-DURIP, IBM-SUR, and the Beckman Institute.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-PS36-06GO96018
Department of Energy (DOE)DE-PS36-03GO93015
NSFCTS-0608889
Chevron CorporationUNSPECIFIED
Army Research Office (ARO)UNSPECIFIED
Office of Naval Research (ONR)UNSPECIFIED
IBMUNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Issue or Number:34
Record Number:CaltechAUTHORS:20170424-141751189
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170424-141751189
Official Citation:Pd-Mediated Activation of Molecular Oxygen:  Pd(0) versus Direct Insertion Jason M. Keith, William A. Goddard, III, and Jonas Oxgaard Journal of the American Chemical Society 2007 129 (34), 10361-10369 DOI: 10.1021/ja070462d
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76868
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 Apr 2017 22:34
Last Modified:28 Feb 2020 00:00

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