Ammonia Mobilizes Cobalt Ions in Zeolites to Form Dimeric Active Sites for Ethane Activation

Ammonia Mobilizes Cobalt Ions in Zeolites to Form Dimeric Active Sites for Ethane Activation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Ammonia Mobilizes Cobalt Ions in Zeolites to Form Dimeric Active Sites for Ethane Activation David Flaherty, Yongwoo Kim, Asanka Wijerathne, Mohan Shankar, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9361657/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Integration of metal species with zeolites catalyzes a wide range of molecular transformations. Among these, cobalt ions stabilized within aluminosilicate zeolites (Co-ZSM-5) catalyze oxidative activation of ethane at practical temperatures (e.g., 648 K). Rate measurement demonstrates that C2H6 and O2 react at isolated monomeric cobalt sites. The introduction of NH3, however, forms mobile cobalt-ammine complexes that persist even at high temperatures requisite for C-H activation. These complexes possess sufficient mobility to dimerize and form oxygen-bridged dicobalt-ammine centers, which activate C-H bonds and form C-N bonds at 648 K, evidenced by in situ UV-vis, XAS, Raman spectroscopies, and kinetic analysis. Quantum chemical and molecular dynamics simulations reveal that the zeolite framework atomically disperses the cationic cobalt atoms, facilitates the spontaneous formation of cobalt-ammine complexes in the presence of NH3, and then enables dimerization with O2 by screening repulsive forces between the cobalt-ammines. These findings demonstrate an unusual transformation of active sites during catalytic turnover in zeolites: dimeric organometallic complexes competent for multistep reactions may form and decompose during each catalytic turnover to bypass kinetic hurdles encountered at monomeric structures. Physical sciences/Chemistry/Catalysis/Heterogeneous catalysis Physical sciences/Chemistry/Catalysis/Catalytic mechanisms Physical sciences/Chemistry/Theoretical chemistry/Reaction mechanisms Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryInformation.pdf Supplementary Information DataS1.zip Data S1 Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9361657","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":619942242,"identity":"897fad1d-bb27-42b2-800a-6644bf1bcc2d","order_by":0,"name":"David 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