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C–H activation and metalation at electrode surfaces: 2,3-dimethyl-1,4-dihydroxybenzene on Pd(pc) and Pd(111) studied by TLE, HREELS and DFT

Javier, Alnald and Li, Ding and Cruz, Juan and Binamira-Soriaga, Elizabeth and Balbuena, Perla B. and Soriaga, Manuel P. (2014) C–H activation and metalation at electrode surfaces: 2,3-dimethyl-1,4-dihydroxybenzene on Pd(pc) and Pd(111) studied by TLE, HREELS and DFT. Dalton Transactions, 43 (39). pp. 14798-14805. ISSN 1477-9226. https://resolver.caltech.edu/CaltechAUTHORS:20140829-081408528

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Abstract

Previous studies, based on thin-layer electrochemistry (TLE), in situ scanning tunneling microscopy (EC-STM), high-resolution electron energy loss spectroscopy (HREELS) and density functional theory (DFT) computations, on the chemical adsorption of hydroquinone from aqueous solutions onto atomically smooth Pd (and Pt) electrode surfaces indicated two modes of attachment that depended upon the solution concentration. At low activities, the diphenol was oxidatively chemisorbed as benzoquinone in a flat orientation, suggestive of a Pd(2,3,5,6-η-C_6H_4O_2) surface complex; at higher concentrations, vertical chemisorption was effected via two C–H bond activations (or metalations) at the 2 and 3 ring positions, evocative of an o-phenylene organopalladium compound. We have extended the work to 2,3-dimethyl-1,4-dihydroxybenzene on Pd(pc) and Pd(111) electrodes to probe the effect of two methyl substituents on only one side of the diphenol ring. Surface coverage and adsorbed-molecule cross section data from TLE and HREELS measurements revealed non-random concentration-dependent adsorbate orientations similar to the oxidative chemisorption of hydroquinone: flat at low concentrations and edgewise at elevated concentrations. The DFT results suggested that, for the flat structure, surface coordination is via the two double bonds of the quinone ring as in [Pd(2,3,5,6-η)-2,3-dimethyl-p-quinone]. For the edge-vertical orientation, a structure analogous to an o-phenylene compound is generated in which C–H bonds at the 5 and 6 ring positions are activated and then metalated. DFT-simulated HREELS spectra helped identify the observed peaks that distinguish the surface-coordinated quinone from the surface-metalated diphenol.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1039/c4dt02137aDOIArticle
http://pubs.rsc.org/en/Content/ArticleLanding/2014/DT/C4DT02137APublisherArticle
ORCID:
AuthorORCID
Soriaga, Manuel P.0000-0002-0077-6226
Additional Information:© 2014 The Royal Society of Chemistry. Received 15 Jul 2014, Accepted 05 Aug 2014, First published online 06 Aug 2014. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: The surface organometallic work, spectroscopic interpretations and DFT analysis were supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993; the TLE and HREELS experiments were supported by the Texas A&M University-CONACYT program (MPS).
Group:JCAP
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Texas A&M University-CONACYTUNSPECIFIED
Issue or Number:39
Record Number:CaltechAUTHORS:20140829-081408528
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140829-081408528
Official Citation:C–H activation and metalation at electrode surfaces: 2,3-dimethyl-1,4-dihydroxybenzene on Pd(pc) and Pd(111) studied by TLE, HREELS and DFT Alnald Javier, Ding Li, Juan Cruz, Elizabeth Binamira-Soriaga, Perla B. Balbuena and Manuel P. Soriaga Dalton Trans., 2014, 43, 14798-14805 DOI: 10.1039/C4DT02137A
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49040
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:29 Aug 2014 20:46
Last Modified:03 Oct 2019 07:10

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