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CO Coupling Chemistry of a Terminal Mo Carbide: Sequential Addition of Proton, Hydride, and CO Releases Ethenone

Buss, Joshua A. and Bailey, Gwendolyn A. and Oppenheim, Julius and VanderVelde, David G. and Goddard, William A., III and Agapie, Theodor (2019) CO Coupling Chemistry of a Terminal Mo Carbide: Sequential Addition of Proton, Hydride, and CO Releases Ethenone. Journal of the American Chemical Society, 141 (39). pp. 15664-15674. ISSN 0002-7863. https://resolver.caltech.edu/CaltechAUTHORS:20190904-110429088

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Abstract

The mechanism originally proposed by Fischer and Tropsch for carbon monoxide (CO) hydrogenative catenation involves C–C coupling from a carbide-derived surface methylidene. A single molecular system capable of capturing these complex chemical steps is hitherto unknown. Herein, we demonstrate the sequential addition of proton and hydride to a terminal Mo carbide derived from CO. The resulting anionic methylidene couples with CO (1 atm) at low temperature (−78 °C) to release ethenone. Importantly, the synchronized delivery of two reducing equivalents and an electrophile, in the form of a hydride (H– = 2e– + H+), promotes alkylidene formation from the carbyne precursor and enables coupling chemistry, under conditions milder than those previously described with strong one-electron reductants and electrophiles. Thermodynamic measurements bracket the hydricity and acidity requirements for promoting methylidene formation from carbide as energetically viable relative to the heterolytic cleavage of H2. Methylidene formation prior to C–C coupling proves critical for organic product release, as evidenced by direct carbide carbonylation experiments. Spectroscopic studies, a monosilylated model system, and Quantum Mechanics computations provide insight into the mechanistic details of this reaction sequence, which serves as a rare model of the initial stages of the Fischer–Tropsch synthesis.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/jacs.9b07743DOIArticle
ORCID:
AuthorORCID
Buss, Joshua A.0000-0002-3347-8583
Bailey, Gwendolyn A.0000-0002-6636-4128
Oppenheim, Julius0000-0002-5988-0677
VanderVelde, David G.0000-0002-2907-0366
Goddard, William A., III0000-0003-0097-5716
Agapie, Theodor0000-0002-9692-7614
Additional Information:© 2019 American Chemical Society. Received: July 22, 2019; Published: September 3, 2019. We thank Larry Henling and Mike Takase for invaluable crystallographic assistance. J.A.B. is grateful for an NSF graduate research fellowship, G.A.B. for NSERC and Resnick Sustainability Institute fellowships, and J.O. for an Ernest H. Swift Summer Undergraduate Research Fellowship. We thank the NSF (CHE-1800501), the Dow Next Generation Education Fund (instrumentation), and Caltech for funding. The computational studies were supported by the NSF (CBET-1805022). The authors declare no competing financial interest.
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Resnick Sustainability InstituteUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
NSFCHE-1800501
Dow Next Generation Educator FundUNSPECIFIED
NSFCBET-1805022
Other Numbering System:
Other Numbering System NameOther Numbering System ID
WAG1350
Issue or Number:39
Record Number:CaltechAUTHORS:20190904-110429088
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190904-110429088
Official Citation:CO Coupling Chemistry of a Terminal Mo Carbide: Sequential Addition of Proton, Hydride, and CO Releases Ethenone. Joshua A. Buss, Gwendolyn A. Bailey, Julius Oppenheim, David G. VanderVelde, William A. Goddard, III, and Theodor Agapie. Journal of the American Chemical Society 2019 141 (39), 15664-15674 DOI: 10.1021/jacs.9b07743
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98409
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Sep 2019 21:06
Last Modified:20 Feb 2020 20:11

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