{"id":28290,"date":"2025-02-01T09:53:41","date_gmt":"2025-02-01T09:53:41","guid":{"rendered":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28290"},"modified":"2025-02-01T09:58:07","modified_gmt":"2025-02-01T09:58:07","slug":"au-pseudocarbyne-a-unusual-example-of-a-twelve-coordination-by-carbon","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28290","title":{"rendered":"Au-pseudocarbyne – a unusual example of a twelve coordination by carbon."},"content":{"rendered":"
\n

Derek Lowe tells the story of “carbyne”<\/a>, a potential further allotrope of carbon, comprising linear chains of carbon atoms, C-C\u2261C-C\u2261C-C. Whether such a molecule can exist on its own has long been the the topic of speculation. Now a report has appeared of a “pseudocarbyne”, stabilised by gold atoms.[1]<\/a><\/span><\/p>\n

The now thankfully almost ubiquitous data availability statement includes the DOI: https:\/\/doi.org\/10.48349\/ASU\/3TWEI0<\/a> [2]<\/a><\/span> as a data repository\u00a0source of replication data<\/em> and one of the files found there is a CIF containing the crystal data. Playing with this, I noticed one unusual feature of this structure, which oddly is not apparently mentioned in the article itself and so I thought I would tease it out here – 12 coordination.<\/p>\n

\"\"<\/p>\n

Ths simplest unit comprises three eight membered carbon rings, each connected by 4-membered rings to form a local structure with D3h symmetry and hence revealing twelve C-Au bonds of the same length; 2.415\u00c5. Click on the image above to view a\u00a03D model.<\/p>\n

A larger section of the (polymeric) structure is shown below, now with D2h symmetry and again with twelve identical C-Au bond lengths<\/p>\n

\"\"<\/p>\n

Is such coordination unusual?‡<\/sup> Well, not for metal clusters, including Au clusters. There are in fact 2014 hits (1985 examples where Y is constrained to be a metal, hence 29 where the central atom is NOT a metal) in the Cambridge crystal structure database for the general search X12<\/sub>Y where X and Y can be any atom, with 244 for X=Au and\u00a0576 for X=O but none yet for X=C (the current example has not yet appeared in the distributed database). So certainly Au-pseudocarbyne is a unique and unusual molecule. This also shows that 3D coordinates can always be a useful adjunct to articles to allow quick access for spotting perhaps unexpected features with just a single click!<\/p>\n

\n

‡<\/sup>You might be surprised that a similar search finds 138 hits for X14<\/sub>Y and 16 for X16<\/sub>Y<\/p>\n

References<\/h2>\n
  1. J. Wu, P. Tarakeshwar, S.G. Sayres, M. Meneghetti, H. Kim, J. Barreto, and P.R. Buseck, \"Crystal structure of Au-pseudocarbyne(C6)\", Scientific Reports<\/i>, vol. 15, 2025. https:\/\/doi.org\/10.1038\/s41598-024-80359-5<\/a>\n\n<\/li>\n
  2. J. Wu, P. Tarakeshwar, S.G. Sayres, M. Meneghetti, H. Kim, J. Barreto, and P.R. Buseck, \"Replication Data for: Crystal structure of Au-pseudocarbyne(C6)\", 2024. https:\/\/doi.org\/10.48349\/asu\/3twei0<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    Derek Lowe tells the story of “carbyne”, a potential further allotrope of carbon, comprising linear chains of carbon atoms, C-C\u2261C-C\u2261C-C. Whether such a molecule can exist on its own has long been the the topic of speculation. Now a report has appeared of a “pseudocarbyne”, stabilised by gold atoms. The now thankfully almost ubiquitous data […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_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}},"categories":[4],"tags":[],"ppma_author":[2661],"class_list":["post-28290","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\nAu-pseudocarbyne - a unusual example of a twelve coordination by carbon. - 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=28290\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Au-pseudocarbyne - a unusual example of a twelve coordination by carbon. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Derek Lowe tells the story of “carbyne”, a potential further allotrope of carbon, comprising linear chains of carbon atoms, C-C\u2261C-C\u2261C-C. 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Whether or not it can be described as having a quadruple bond has induced much passionate discussion,,,. Its occurrence in space and in flames is also well-known. But does it have what might be called a conventional chemistry? Other highly\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":"Click for 3D","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/07\/LaOsC1.jpeg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":17829,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17829","url_meta":{"origin":28290,"position":1},"title":"First, hexacoordinate carbon – now pentacoordinate nitrogen?","author":"Henry Rzepa","date":"March 25, 2017","format":false,"excerpt":"A few years back I followed a train of thought here which ended with hexacoordinate carbon, then a hypothesis rather than a demonstrated reality. That reality was recently confirmed via a crystal structure,\u00a0DOI:10.5517\/CCDC.CSD.CC1M71QM. Here is a\u00a0similar proposal for\u00a0penta-coordinate nitrogen. First, a search of the CSD (Cambridge structure database) for such\u00a0nitrogen.\u2026","rel":"","context":"In "Bond slam"","block_context":{"text":"Bond slam","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2237"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":28187,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28187","url_meta":{"origin":28290,"position":2},"title":"Molecules of the Year 2024: A crystal structure perspective on anti-Bredt olefins.","author":"Henry Rzepa","date":"January 8, 2025","format":false,"excerpt":"Each year C&E News publishes a list of candidates for the Molecule of the Year. For 2024 the list is (in order of votes cast for each) Mirror-image cyclodextrin Molecular shuttle in a box Rule-bending strained alkene First soluble promethium complex Single-electron carbon-carbon bond Hot MOF for capturing carbon I\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":845,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=845","url_meta":{"origin":28290,"position":3},"title":"It’s penta-coordinate carbon Spock- but not as we know it!","author":"Henry Rzepa","date":"September 30, 2009","format":false,"excerpt":"In the previous two posts, I noted the recent suggestion of how a stable frozen SN2 transition state might be made. This is characterised by a central carbon with five coordinated ligands. The original suggestion included two astatine atoms as ligands (X=At), but in my post I suggested an alternative\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"The Sn2 transition state","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/09\/sn2.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":27788,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=27788","url_meta":{"origin":28290,"position":4},"title":"A carbon-carbon one-electron bond! Or a weak carbon-carbon interaction?","author":"Henry Rzepa","date":"October 1, 2024","format":false,"excerpt":"More than 100 years ago, before the quantum mechanical treatment of molecules had been formulated, G. N. Lewis proposed a simple model for chemical bonding that is still taught today. This is the idea of the three categories of bond we know as single, double and triple, comprising respectively two,\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":9894,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=9894","url_meta":{"origin":28290,"position":5},"title":"To be cyclobutadiene, or not to be, that is the question? You decide.","author":"Henry Rzepa","date":"March 21, 2013","format":false,"excerpt":"A quartet of articles has recently appeared on the topic of cyclobutadiene.,,,. You will find a great deal discussed there, but I can boil it down to this essence. Do the following coordinates (obtained from a (disordered) previously published x-ray refinement) correspond to a van der Waals complex of 1,3-dimethyl\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","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28290","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=28290"}],"version-history":[{"count":9,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28290\/revisions"}],"predecessor-version":[{"id":28303,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28290\/revisions\/28303"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28290"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28290"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28290"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=28290"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}