{"id":16987,"date":"2016-10-13T11:37:45","date_gmt":"2016-10-13T10:37:45","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=16987"},"modified":"2016-10-14T06:36:58","modified_gmt":"2016-10-14T05:36:58","slug":"catenated-atoms-and-groups","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987","title":{"rendered":"Catenated atoms and groups."},"content":{"rendered":"
\n

Chemists are as fond of records as any, although I doubt you will find many\u00a0chemical ones\u00a0in the Guinness world records<\/a> list. Polytriangulanes chase how many cyclopropyl 3-rings can be joined via<\/em> a vertex. Steve Bachrach on his blog<\/a> reports some recent work by Peter Schreiner and colleagues[1]<\/a><\/span> and the record for catenation of such rings appears to be 15. This led me to think about some other common atoms and groups. Here I have searched for crystal structures only; there may be examples of course for which no such data has been reported.<\/p>\n

    \n
  1. For the halogens F and Cl it is 3.\u00a0<\/li>\n
  2. But for Br,\u00a0believe it or not it reaches the heady value of 24, doi:\u00a010.5517\/CC14K0PD<\/a>[2]<\/a><\/span><\/li>\n
  3. For iodine it is effectively infinite, as noted in my earlier post<\/a>.<\/li>\n
  4. For oxygen it is 3; there are none with four consecutive oxygens.<\/li>\n
  5. For sulfur, a ring of twelve is known[3]<\/a><\/span> and for Se ~11[4]<\/a><\/span><\/li>\n
  6. For nitrogen it may surprise to learn it reaches 6 if the connecting bonds are all single.\u00a0A typical example can be seen at doi:\u00a010.5517\/CCZCR35<\/a>[5]<\/a><\/span> It reaches 10 if any kind of \u00a0N-N bond is allowed. doi:\u00a010.5517\/CCYVNZD<\/a><\/li>\n
  7. For phosphorus, 16 is not uncommon 10.5517\/CC1JWTQY<\/a> [6]<\/a><\/span> but the record may be 21.<\/li>\n
  8. The\u00a0alkyne group C\u2261C, reaches 10 (20 carbon atoms), doi:\u00a010.5517\/CCSGR98<\/a>\u00a0[7]<\/a><\/span><\/li>\n
  9. The carbonyl group\u00a0(C=O) can form a ring of six such groups 10.5517\/CC9JR6R<\/a>[8]<\/a><\/span><\/li>\n<\/ol>\n

    Such records are probably very uncompetitive; I doubt any researchers set out to extend the count. Most of the above are probably simply unexpected discoveries. My favourite is the bromine example; this element so often surprises<\/a>.<\/p>\n

    References<\/h2>\n
    1. W.D. Allen, H. Quanz, and P.R. Schreiner, \"Polytriangulane\", Journal of Chemical Theory and Computation<\/i>, vol. 12, pp. 4707-4716, 2016. https:\/\/doi.org\/10.1021\/acs.jctc.6b00669<\/a>\n\n<\/li>\n
    2. Easton, Max E.., Ward, Antony J.., Hudson, Toby., Turner, Peter., Masters, Anthony F.., and Maschmeyer, Thomas., \"CCDC 1059043: Experimental Crystal Structure Determination\", 2015. https:\/\/doi.org\/10.5517\/cc14k0pd<\/a>\n\n<\/li>\n
    3. J. Steidel, R. Steudel, and A. Kutoglu, \"R\u00f6ntgenstrukturanalysen von Cyclododekaschwefel (S<sub>12<\/sub>) und Cyclododekaschwefel\u20101\u2010Kohlendisulfid (S<sub>12<\/sub> \u00b7 CS<sub>2<\/sub>) [1]\", Zeitschrift f\u00fcr anorganische und allgemeine Chemie<\/i>, vol. 476, pp. 171-178, 1981. https:\/\/doi.org\/10.1002\/zaac.19814760520<\/a>\n\n<\/li>\n
    4. M.G. Kanatzidis, and S.P. Huang, \"Unanticipated redox transformations in gold polyselenides. Isolation and characterization of diselenobis(tetraselenido)diaurate(2-) and undecaselenido(2-)\", Inorganic Chemistry<\/i>, vol. 28, pp. 4667-4669, 1989. https:\/\/doi.org\/10.1021\/ic00325a026<\/a>\n\n<\/li>\n
    5. Klapotke, T.M.., Petermayer, C.., Piercey, D.G.., and Stierstorfer, J.., \"CCDC 905017: Experimental Crystal Structure Determination\", 2013. https:\/\/doi.org\/10.5517\/cczcr35<\/a>\n\n<\/li>\n
    6. Dragulescu-Andrasi, Alina., Miller, L. Zane., Chen, Banghao., McQuade, D. Tyler., and Shatruk, Michael., \"CCDC 1426921: Experimental Crystal Structure Determination\", 2016. https:\/\/doi.org\/10.5517\/cc1jwtqy<\/a>\n\n<\/li>\n
    7. Chalifoux, W.A.., McDonald, R.., Ferguson, M.J.., and Tykwinski, R.R.., \"CCDC 729160: Experimental Crystal Structure Determination\", 2010. https:\/\/doi.org\/10.5517\/ccsgr98<\/a>\n\n<\/li>\n
    8. Abrahams, B.F.., Haywood, M.G.., and Robson, R.., \"CCDC 284214: Experimental Crystal Structure Determination\", 2006. https:\/\/doi.org\/10.5517\/cc9jr6r<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

      Chemists are as fond of records as any, although I doubt you will find many\u00a0chemical ones\u00a0in the Guinness world records list. Polytriangulanes chase how many cyclopropyl 3-rings can be joined via a vertex. Steve Bachrach on his blog reports some recent work by Peter Schreiner and colleagues and the record for catenation of such rings […]<\/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":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_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},"categories":[1745],"tags":[],"ppma_author":[2661],"class_list":["post-16987","post","type-post","status-publish","format-standard","hentry","category-crystal_structure_mining"],"yoast_head":"\nCatenated atoms and groups. - 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=16987\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Catenated atoms and groups. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Chemists are as fond of records as any, although I doubt you will find many\u00a0chemical ones\u00a0in the Guinness world records list. Polytriangulanes chase how many cyclopropyl 3-rings can be joined via a vertex. Steve Bachrach on his blog reports some recent work by Peter Schreiner and colleagues and the record for catenation of such rings […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2016-10-13T10:37:45+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2016-10-14T05:36:58+00:00\" \/>\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=\"1 minute\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Catenated atoms and groups. - 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=16987","og_locale":"en_GB","og_type":"article","og_title":"Catenated atoms and groups. - Henry Rzepa's Blog","og_description":"Chemists are as fond of records as any, although I doubt you will find many\u00a0chemical ones\u00a0in the Guinness world records list. Polytriangulanes chase how many cyclopropyl 3-rings can be joined via a vertex. Steve Bachrach on his blog reports some recent work by Peter Schreiner and colleagues and the record for catenation of such rings […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987","og_site_name":"Henry Rzepa's Blog","article_published_time":"2016-10-13T10:37:45+00:00","article_modified_time":"2016-10-14T05:36:58+00:00","author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"Catenated atoms and groups.","datePublished":"2016-10-13T10:37:45+00:00","dateModified":"2016-10-14T05:36:58+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987"},"wordCount":300,"commentCount":3,"articleSection":["crystal_structure_mining"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987","name":"Catenated atoms and groups. - Henry Rzepa's Blog","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website"},"datePublished":"2016-10-13T10:37:45+00:00","dateModified":"2016-10-14T05:36:58+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=16987#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16987#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"Catenated atoms and groups."}]},{"@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":"Henry Rzepa is 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_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pDef7-4pZ","jetpack-related-posts":[{"id":30548,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=30548","url_meta":{"origin":16987,"position":0},"title":"Molecules of the year 2025: Benzene-busting inverted sandwich.","author":"Henry Rzepa","date":"January 1, 2026","format":false,"excerpt":"Sandwich compounds are the colloquial term used for molecules where a metal atom such as an iron dication is \"sandwiched\" between two carbon-based rings as ligands, most commonly cyclopentadienyl anion (the \"bread\") as in e.g. Ferrocene - a molecule first discovered in 1951. An \"inverted\" sandwich is where the carbon\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":16573,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16573","url_meta":{"origin":16987,"position":1},"title":"How does an OH or NH group approach an aromatic ring to hydrogen bond with its \u03c0-face?","author":"Henry Rzepa","date":"June 22, 2016","format":false,"excerpt":"I previously used data mining of crystal structures to explore the directing influence of substituents on aromatic and heteroaromatic rings. Here\u00a0I explore, quite literally, a different angle to the hydrogen bonding interactions between a benzene ring and\u00a0OH or NH groups. I start by defining a benzene ring with a centroid.\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":"aromatic-pi-query","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2016\/06\/aromatic-pi-query-1-e1466580253270.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":15635,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=15635","url_meta":{"origin":16987,"position":2},"title":"Bond stretch isomerism. Did this idea first surface 100 years ago?","author":"Henry Rzepa","date":"February 9, 2016","format":false,"excerpt":"The phenomenon of bond stretch isomerism, two isomers of a compound differing predominantly in just one bond length, is one of those chemical concepts that wax and occasionally\u00a0wane. Here I explore such isomerism for the elements Ge, Sn and Pb. In one earlier post, I noted a form of\u00a0bond stretch\u2026","rel":"","context":"In "crystal_structure_mining"","block_context":{"text":"crystal_structure_mining","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1745"},"img":{"alt_text":"lewis1","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2016\/02\/lewis1-1-1024x421.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":21883,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=21883","url_meta":{"origin":16987,"position":3},"title":"Molecules of the year 2019: Hexagonal planar crystal structures.","author":"Henry Rzepa","date":"January 23, 2020","format":false,"excerpt":"Here is another selection from the Molecules-of-the-Year shortlist published by C&E News, in which hexagonal planar transition metal coordination is identified. This was a mode of metal coordination first mooted more than 100 years ago, but with the first examples only being discovered recently.\u00a0The C&E News example comprises a central\u2026","rel":"","context":"In "crystal_structure_mining"","block_context":{"text":"crystal_structure_mining","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1745"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/01\/norloy-300x263.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":24380,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24380","url_meta":{"origin":16987,"position":4},"title":"More examples of crystal structures containing embedded linear chains of iodines.","author":"Henry Rzepa","date":"October 17, 2021","format":false,"excerpt":"The previous post described the fascinating 170-year history of a crystalline compound known as Herapathite and its connection to the mechanism of the Finkelstein reaction via the complex of Na+I2- (or Na22+I42-). Both compounds exhibit (approximately) linear chains of iodine atoms in their crystal structures, a connection which was discovered\u2026","rel":"","context":"In "Chiroptics"","block_context":{"text":"Chiroptics","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2644"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/10\/Screenshot-925-1024x248.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":29799,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=29799","url_meta":{"origin":16987,"position":5},"title":"Short B-H…H-O Interactions in crystal structures – a short DFT Exploration using B3LYP+D4 and r2scan-3c","author":"Henry Rzepa","date":"October 27, 2025","format":false,"excerpt":"In the previous post, I was commenting that the transition state for borohydride reduction of a ketone contained some close contacts between the hydrogen of the borohydride and the hydrogen of water. A systematic search of the CSD reveals a modest number of such contacts have been observed in crystal\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","author_category":"1","first_name":"Henry","last_name":"Rzepa","user_url":"https:\/\/orcid.org\/0000-0002-8635-8390","job_title":"","description":"Henry Rzepa is Emeritus Professor of Computational Chemistry at Imperial College London."}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/16987","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=16987"}],"version-history":[{"count":9,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/16987\/revisions"}],"predecessor-version":[{"id":16996,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/16987\/revisions\/16996"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16987"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16987"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16987"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=16987"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}