The cumulenic linear C5 and its coupling-reaction products

The cumulenic linear C5 and its coupling-reaction products | 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 Physical Sciences - Article The cumulenic linear C5 and its coupling-reaction products Wei Xu, Luye Sun, Yuan Guo, Wenzhi Xiang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5912729/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Oct, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Linear carbon (Cn), an elusive sp-hybridized carbon allotrope, has attracted much interests both experimentally and among theorists for decades due to remarkable properties and significant controversy. Similar to recently popular sp-hybridized cyclo[n]carbon, linear carbon may also have two distinct structural forms, i.e., cumulene for consecutive double bonds, or polyyne for alternating triple and single bonds. Peierls transition theory predicted that for infinite linear Cn, polyyne should be more stable than cumulene, and meanwhile opening a band gap at Fermi level. Due to its very high reactivity, synthesis and characterization of linear carbon are exceptionally challenging. Previous works have tried different methods, especially heavy end-capping groups or confined into carbon nanotube, to synthesize carbon chains, however, atomically precise synthesis of uncapped linear carbon, and real-space characterization of its detailed structure remains very rare. Especially, its cumulenic form, is proved to be even harder to synthesize compared to polyynic one. In solution, till now, the longest cumulene known to date is n = 9 (also with protected group at both ends). Here, we report the synthesis of an uncapped linear C5 via tip-induced dehalogenation and ring-opening reaction of a fully halogenated precursor, C5Br6, and characterization of it cumulenic structure by bond-resolved atomic force microscopy (AFM). Furthermore, we demonstrate that it is feasible to achieve tip-induced cascade reactions among linear C5, leading to the successful synthesis of longer carbon chains, for example, C10, C15. Inspired by that, utilizing the tip to apply larger voltage pulses (~4.5 V), carbon chains with various lengths, including C9, C10, C13, C14, C15, C17, C18, C21, could be efficiently synthesized, which provide us an ideal system to study the influence of number of carbon atoms and odevity effect on the structure of linear carbon, and moreover, to investigate the relationship between structures and related electronic properties. For the even-numbered chains (i.e., C10, C14 and C18), the polyynic structure emerges, due to the occurrence of Peierls transition within such finite carbon chains induced by NaCl surface, similar to the case of linear C6. Interestingly, for the odd-numbered chain, i.e., C9, it presents a cumulene-like structure (with rather small bond length alternations). While, for longer ones, i.e., C13, C15, C17, and C21, the major moieties are still cumulene-like structures and the both ends present triple bond characteristics. Scanning tunneling spectroscopy (STS) measurements further reveal that the transport gaps of odd-numbered chains are obviously smaller than that of even-numbered chains, validating the structures assigned above, and the transport gaps gradually decrease with increasing number of carbon atoms. Our findings exhibit an on-surface method for atomically precise synthesis of a series of linear carbon, rendering further investigation of their unique structures and electronic properties. Physical sciences/Chemistry/Physical chemistry/Chemical physics Physical sciences/Chemistry/Surface chemistry/Scanning probe microscopy Full Text Additional Declarations There is NO Competing Interest. Supplementary Files supportinginformation.doc supporting information Cite Share Download PDF Status: Published Journal Publication published 17 Oct, 2025 Read the published version in Nature Communications → 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-5912729","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":408118877,"identity":"a08febfc-b44e-4ca4-ac5f-483c8cc9a794","order_by":0,"name":"Wei Xu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1UlEQVRIiWNgGAWjYLCChAoIdYCBgZlYLWcMSNXC2GYAYxKhxeBGjuGDh/P+yJnzL3h4gKHCOrGB/ewBvFokZ+QYGyRuMzC2nPEA6LAz6YkNPHkJeLXwS+RukwBqSdxw40DCAca2w4kNEjwGeLWwSeRu/5E4B6blHxFaQLYwJDYAtZxvAGppIEKLZM/7zxIJx4yNDW4AAznhWLpxG08Ofi0Gx9MSP/6okZMzOH8m+cOHGmvZfvYz+LUggEROAkMCyHdEqgcC/uMHiFc8CkbBKBgFIwoAABk4Sxv3Fh6sAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0003-0216-794X","institution":"Tongji University","correspondingAuthor":true,"prefix":"","firstName":"Wei","middleName":"","lastName":"Xu","suffix":""},{"id":408118878,"identity":"5542c837-49da-497b-99b3-7854042702d9","order_by":1,"name":"Luye Sun","email":"","orcid":"https://orcid.org/0000-0003-2678-2517","institution":"Tongji University","correspondingAuthor":false,"prefix":"","firstName":"Luye","middleName":"","lastName":"Sun","suffix":""},{"id":408118880,"identity":"a1a94c83-4fec-438c-b104-2c1983141802","order_by":2,"name":"Yuan Guo","email":"","orcid":"","institution":"Tongji University","correspondingAuthor":false,"prefix":"","firstName":"Yuan","middleName":"","lastName":"Guo","suffix":""},{"id":408118881,"identity":"e4aedc58-33b4-4cb2-aee8-243b19ffb4eb","order_by":3,"name":"Wenzhi Xiang","email":"","orcid":"","institution":"Tongji University","correspondingAuthor":false,"prefix":"","firstName":"Wenzhi","middleName":"","lastName":"Xiang","suffix":""}],"badges":[],"createdAt":"2025-01-27 13:50:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5912729/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5912729/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-025-64310-4","type":"published","date":"2025-10-17T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":93827317,"identity":"297dad6c-2e2a-4b57-8138-c212b34a311e","added_by":"auto","created_at":"2025-10-18 07:06:01","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":784825,"visible":true,"origin":"","legend":"","description":"","filename":"manuscriptXu.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5912729/v1_covered_38285903-9971-40da-995f-5c0948c012d9.pdf"},{"id":75652038,"identity":"ca723951-a546-47c1-937c-f8e9b5821d91","added_by":"auto","created_at":"2025-02-06 18:14:12","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2850816,"visible":true,"origin":"","legend":"supporting information","description":"","filename":"supportinginformation.doc","url":"https://assets-eu.researchsquare.com/files/rs-5912729/v1/0302916a2e0a06a6c7524da1.doc"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"The cumulenic linear C5 and its coupling-reaction products","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5912729/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5912729/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Linear carbon (Cn), an elusive sp-hybridized carbon allotrope, has attracted much interests both experimentally and among theorists for decades due to remarkable properties and significant controversy. Similar to recently popular sp-hybridized cyclo[n]carbon, linear carbon may also have two distinct structural forms, i.e., cumulene for consecutive double bonds, or polyyne for alternating triple and single bonds. Peierls transition theory predicted that for infinite linear Cn, polyyne should be more stable than cumulene, and meanwhile opening a band gap at Fermi level. Due to its very high reactivity, synthesis and characterization of linear carbon are exceptionally challenging. Previous works have tried different methods, especially heavy end-capping groups or confined into carbon nanotube, to synthesize carbon chains, however, atomically precise synthesis of uncapped linear carbon, and real-space characterization of its detailed structure remains very rare. Especially, its cumulenic form, is proved to be even harder to synthesize compared to polyynic one. In solution, till now, the longest cumulene known to date is n = 9 (also with protected group at both ends). Here, we report the synthesis of an uncapped linear C5 via tip-induced dehalogenation and ring-opening reaction of a fully halogenated precursor, C5Br6, and characterization of it cumulenic structure by bond-resolved atomic force microscopy (AFM). Furthermore, we demonstrate that it is feasible to achieve tip-induced cascade reactions among linear C5, leading to the successful synthesis of longer carbon chains, for example, C10, C15. Inspired by that, utilizing the tip to apply larger voltage pulses (~4.5 V), carbon chains with various lengths, including C9, C10, C13, C14, C15, C17, C18, C21, could be efficiently synthesized, which provide us an ideal system to study the influence of number of carbon atoms and odevity effect on the structure of linear carbon, and moreover, to investigate the relationship between structures and related electronic properties. For the even-numbered chains (i.e., C10, C14 and C18), the polyynic structure emerges, due to the occurrence of Peierls transition within such finite carbon chains induced by NaCl surface, similar to the case of linear C6. Interestingly, for the odd-numbered chain, i.e., C9, it presents a cumulene-like structure (with rather small bond length alternations). While, for longer ones, i.e., C13, C15, C17, and C21, the major moieties are still cumulene-like structures and the both ends present triple bond characteristics. Scanning tunneling spectroscopy (STS) measurements further reveal that the transport gaps of odd-numbered chains are obviously smaller than that of even-numbered chains, validating the structures assigned above, and the transport gaps gradually decrease with increasing number of carbon atoms. Our findings exhibit an on-surface method for atomically precise synthesis of a series of linear carbon, rendering further investigation of their unique structures and electronic properties.","manuscriptTitle":"The cumulenic linear C5 and its coupling-reaction products","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-06 18:14:07","doi":"10.21203/rs.3.rs-5912729/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ff05cf22-c10e-45e9-988a-cb3f39cbca91","owner":[],"postedDate":"February 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":43512159,"name":"Physical sciences/Chemistry/Physical chemistry/Chemical physics"},{"id":43512161,"name":"Physical sciences/Chemistry/Surface chemistry/Scanning probe microscopy"}],"tags":[],"updatedAt":"2025-10-18T07:05:50+00:00","versionOfRecord":{"articleIdentity":"rs-5912729","link":"https://doi.org/10.1038/s41467-025-64310-4","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2025-10-17 04:00:00","publishedOnDateReadable":"October 17th, 2025"},"versionCreatedAt":"2025-02-06 18:14:07","video":"","vorDoi":"10.1038/s41467-025-64310-4","vorDoiUrl":"https://doi.org/10.1038/s41467-025-64310-4","workflowStages":[]},"version":"v1","identity":"rs-5912729","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5912729","identity":"rs-5912729","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}