{"id":23240,"date":"2021-01-20T14:34:16","date_gmt":"2021-01-20T14:34:16","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=23240"},"modified":"2021-01-21T09:04:53","modified_gmt":"2021-01-21T09:04:53","slug":"the-chemical-synthesis-of-c2-another-fascinating-twist-to-the-story","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240","title":{"rendered":"The chemical synthesis of C2: another fascinating twist to the story."},"content":{"rendered":"
\n

Last May, I wrote an update<\/a> to the story sparked by the report of the chemical synthesis of C2<\/sub>.[1]<\/a><\/span> This species has a long history of spectroscopic observation in the gas phase, resulting from its generation at high temperatures.[2]<\/a><\/span> The chemical synthesis however was done in solution at ambient or low temperatures, a game-changer as they say. Here I give another update to this unfolding story.
\n\"\"<\/a><\/p>\n

Key to the story is the precursor labelled 11<\/b> in the scheme above and the suggestion[1]<\/a><\/span> that it is unimolecular<\/strong> decomposition of 11<\/strong>\u00a0that results in C2<\/sub>. A question that had not been posed however was whether 11<\/strong>\u00a0itself could participate in any bimolecular<\/strong> reactions and whether these could be lower in free energy than its unimolecular decomposition. That has now been addressed in a recent pre-print, DOI: 10.26434\/chemrxiv.13560260.v1<\/a>[3]<\/a><\/span> Here I will show just one of the possible bimolecular reactions investigated, that of 11<\/strong> with itself.\u00a0<\/p>\n

\"\"<\/a>\"\"<\/a>
\n<\/a>The reaction has a low barrier (\u0394G\u2021<\/sup> 15.4 kcal\/mol for a standard state of 0.044 molar, approximately the concentration the original experiments were conducted for) which means it will be very rapid at room temperatures.\u2665<\/sup><\/span> The product of this reaction can itself react with more 11<\/strong> ((\u0394G\u2021<\/sup> 16.9 kcal\/mol) and so on to form polymeric chains or clusters of carbon, eventually resulting in C60<\/sub> and other forms of carbon. Low energy barriers for a number of other possible bimolecular reactions of 11<\/strong> with species such as the chemical traps used in the original experiment are also reported,[3]<\/a><\/span> most of which are lower in free energy than that predicted for the unimolecular fragmentation of 11<\/strong>, despite the entropic penalty.<\/p>\n

So the enigma is thus: Does species 11<\/strong> truly fragment to C2<\/sub>, or are the products of this reaction really bimolecular reactions of 11<\/strong>? It does seem as if 11<\/strong> itself can have a rich and fascinating room temperature chemistry, the scope of which has only started to be explored.<\/p>\n

\n

\u2665<\/sup><\/span>The potential energy surface is unusual, in that initially two products are possible, depending on where the C4<\/sub> unit ends up attached. The potential energy valley only bifurcates into two valleys resulting in the final product at a late stage (~ IRC -5). Put another way, the initial symmetry is C2h<\/sub>, but this breaks\/bifurcates into two valleys each leading to different outcomes for the C4<\/sub> unit. This is very much like the famous potential energy surface for the dimerisation of cyclopentadiene<\/a>.<\/p>\n

References<\/h2>\n
  1. K. Miyamoto, S. Narita, Y. Masumoto, T. Hashishin, T. Osawa, M. Kimura, M. Ochiai, and M. Uchiyama, \"Room-temperature chemical synthesis of C2\", Nature Communications<\/i>, vol. 11, 2020. https:\/\/doi.org\/10.1038\/s41467-020-16025-x<\/a>\n\n<\/li>\n
  2. T.W. Schmidt, \"The Spectroscopy of C<sub>2<\/sub>: A Cosmic Beacon\", Accounts of Chemical Research<\/i>, vol. 54, pp. 481-489, 2021. https:\/\/doi.org\/10.1021\/acs.accounts.0c00703<\/a>\n\n<\/li>\n
  3. H. Rzepa, \"No Free C2 Is Involved in the DFT-Computed Mechanistic Model for the Reported Room-Temperature Chemical Synthesis of C2.\", 2021. https:\/\/doi.org\/10.26434\/chemrxiv.13560260.v1<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    Last May, I wrote an update to the story sparked by the report of the chemical synthesis of C2. This species has a long history of spectroscopic observation in the gas phase, resulting from its generation at high temperatures. The chemical synthesis however was done in solution at ambient or low temperatures, a game-changer as […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_hide_featured_image":false,"_jetpack_featured_image_duplicate_dismissed":0,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false,"_ppma_block_editor_authors":""},"categories":[4],"tags":[],"ppma_author":[2661],"class_list":["post-23240","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\nThe chemical synthesis of C2: another fascinating twist to the story. - Henry Rzepa's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The chemical synthesis of C2: another fascinating twist to the story. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Last May, I wrote an update to the story sparked by the report of the chemical synthesis of C2. This species has a long history of spectroscopic observation in the gas phase, resulting from its generation at high temperatures. The chemical synthesis however was done in solution at ambient or low temperatures, a game-changer as […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2021-01-20T14:34:16+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-01-21T09:04:53+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"The chemical synthesis of C2: another fascinating twist to the story. - Henry Rzepa's Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240","og_locale":"en_GB","og_type":"article","og_title":"The chemical synthesis of C2: another fascinating twist to the story. - Henry Rzepa's Blog","og_description":"Last May, I wrote an update to the story sparked by the report of the chemical synthesis of C2. This species has a long history of spectroscopic observation in the gas phase, resulting from its generation at high temperatures. The chemical synthesis however was done in solution at ambient or low temperatures, a game-changer as […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240","og_site_name":"Henry Rzepa's Blog","article_published_time":"2021-01-20T14:34:16+00:00","article_modified_time":"2021-01-21T09:04:53+00:00","og_image":[{"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg","type":"","width":"","height":""}],"author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"The chemical synthesis of C2: another fascinating twist to the story.","datePublished":"2021-01-20T14:34:16+00:00","dateModified":"2021-01-21T09:04:53+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240"},"wordCount":428,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg","articleSection":["Interesting chemistry"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240","name":"The chemical synthesis of C2: another fascinating twist to the story. - Henry Rzepa's Blog","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg","datePublished":"2021-01-20T14:34:16+00:00","dateModified":"2021-01-21T09:04:53+00:00","author":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"breadcrumb":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#primaryimage","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg","contentUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/Figure1.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23240#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"The chemical synthesis of C2: another fascinating twist to the story."}]},{"@type":"WebSite","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/","name":"Henry Rzepa's Blog","description":"Chemistry with a twist","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-GB"},{"@type":"Person","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281","name":"Henry Rzepa","image":{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g370be3a7397865e4fd161aefeb0a5a85","url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","caption":"Henry Rzepa"},"description":"Emeritus Professor of Computational Chemistry at Imperial College London.","sameAs":["https:\/\/orcid.org\/0000-0002-8635-8390"],"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?author=1"}]}},"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pDef7-62Q","jetpack-related-posts":[{"id":22270,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22270","url_meta":{"origin":23240,"position":0},"title":"Discussion of (the) Room-temperature chemical synthesis of dicarbon – open and transparent science.","author":"Henry Rzepa","date":"May 6, 2020","format":false,"excerpt":"A little more than a year ago, a ChemRxiv pre-print appeared bearing the title referenced in this post, which immediately piqued my curiosity. The report presented persuasive evidence, in the form of trapping experiments, that dicarbon or C2 had been formed by the following chemical synthesis. Here I describe some\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":17951,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17951","url_meta":{"origin":23240,"position":1},"title":"Supporting information: chemical graveyard or invaluable resource for chemical structures.","author":"Henry Rzepa","date":"March 31, 2017","format":false,"excerpt":"Nowadays, data supporting\u00a0most publications relating to the synthesis of organic compounds is more likely than not to be found in associated \"supporting information\" rather than the (often page limited) article itself. For example, this article has an SI which is paginated at 907; almost a mini-database in its own right!\u2020\u2026","rel":"","context":"In "Chemical IT"","block_context":{"text":"Chemical IT","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":20333,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=20333","url_meta":{"origin":23240,"position":2},"title":"The history of Alizarin (and madder).","author":"Henry Rzepa","date":"October 18, 2018","format":false,"excerpt":"The Royal Society of Chemistry historical group (of which I am a member) organises two or three one day meetings a year. Yesterday the October meeting covered (amongst other themes) the fascinating history of madder and its approximately synthetic equivalent alizarin. Here I add a little to the talk given\u2026","rel":"","context":"In "Historical"","block_context":{"text":"Historical","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=565"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":21009,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=21009","url_meta":{"origin":23240,"position":3},"title":"Diatomics with eight valence-electrons: formation by radioactive decay.","author":"Henry Rzepa","date":"June 2, 2019","format":false,"excerpt":"This is a follow up to my earlier post about C\u2a78N+, itself inspired by this ChemRxiv pre-print which describes a chemical synthesis of singlet biradicaloid C2 and its proposed\u00a0identification as such by chemical trapping. First row diatomics based on the iso-electronic principle of eight valence electrons include both C\u2a78N+ and\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":363,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=363","url_meta":{"origin":23240,"position":4},"title":"The chirality of M\u00f6bius annulenes","author":"Henry Rzepa","date":"April 22, 2009","format":false,"excerpt":"Much like climbing Mt. Everest because its there, \u00a0some hypothetical molecules are just too tantalizing for chemists to resist attempting a synthesis. Thus in 1964, Edgar Heilbronner \u00a0speculated on whether a conjugated annulene ring might be twistable into a \u00a0M\u00f6bius strip. It was essentially a fun thing to try to\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"The 16-annulene synthesized by Herges and his team.","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/herges.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":20933,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=20933","url_meta":{"origin":23240,"position":5},"title":"Startling bonds: revisiting C\u2a78N+, via the helium bond in N\u2261C-He+.","author":"Henry Rzepa","date":"May 27, 2019","format":false,"excerpt":"Although the small diatomic molecule known as dicarbon or C2 has been known for a long time, its properties and reactivity have really only been determined\u00a0via its very high temperature generation. My interest started in 2010, when I speculatively proposed here that the related isoelectronic species C\u2a78N+ might sustain a\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"jetpack_likes_enabled":false,"authors":[{"term_id":2661,"user_id":1,"is_guest":0,"slug":"admin","display_name":"Henry Rzepa","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","avatar_alt":"","avatar_decorative":"","author_category":"1","first_name":"Henry","last_name":"Rzepa","user_url":"https:\/\/orcid.org\/0000-0002-8635-8390","job_title":"","description":"Emeritus Professor of Computational Chemistry at Imperial College London."}],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/23240","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=23240"}],"version-history":[{"count":12,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/23240\/revisions"}],"predecessor-version":[{"id":23256,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/23240\/revisions\/23256"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=23240"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=23240"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=23240"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=23240"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}