{"id":28407,"date":"2025-05-16T15:26:48","date_gmt":"2025-05-16T14:26:48","guid":{"rendered":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407"},"modified":"2026-04-05T09:26:49","modified_gmt":"2026-04-05T08:26:49","slug":"cyclo-heptasulfur-s7-a-classic-anomeric-effect-discovered-during-a-pub-lunch","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407","title":{"rendered":"Cyclo-Heptasulfur, S7<\/sub> – a classic anomeric effect discovered during a pub lunch!"},"content":{"rendered":"
\n

Way back in 1977, the crystal structure of the sulfur ring S7<\/sub> was reported.[1]<\/a><\/span> The authors noted that “The \u03b4 modification of S7<\/sub> contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule.<\/em>” No explanation was offered, although they note that similar effects have been observed in S8<\/sub>O, S7<\/sub>I+<\/sup> and S7<\/sub>O. The S7<\/sub> molecule was yesterday brought to my attention (thanks Derek!) over a pub lunch and in the time honoured manner of scientists, sketched out on a napkin – with a pen obtained from the waitress!. As an “organic chemist”, I immediately thought “anomeric effects”. And so indeed it has proven. A calculation using the MN15L\/Def2-TZVPP DFT method and analysis using the Weinhold NBO7 procedure[2]<\/a><\/span> reveals the following structure (with Cs symmetry) and indeed the four unique S-S distances are all different (experimental values in parentheses). So how does this arise?<\/p>\n

\"\"<\/p>\n

Effect 1<\/strong> is the donation of a lone pair from sulfur S4 or S2 into the antibonding orbital of the long S3-S7 bond labelled 2.174Å. The NBO E(2) perturbation energy is 12.35 kcal\/mol, a fairly large effect when you consider that the more conventional value involving oxygen instead of sulfur is ~16 kcal\/mol. There are two such donations (black and red) and so this long bond is doubly lengthened. Simultaneously the S4-S7 or S2-S3 bonds associated with the donor sulfur are shortened to 1.982Å. <\/p>\n

\"\"<\/a><\/p>\n

You can see the orbitals involved below (click on the image to obtain a 3D rotatable model) and consider that the blue phase overlaps positively with the purple and also the red with orange. These overlaps conspire to move electrons from the S4 lone pair into the S4-S7 bond and to move electrons from the S3-S7 bond into an S3 lone pair and hence to shorten the first to give it some π-bond character (Wiberg bond index 1.1796) and to lengthen the second bond (Wiberg bond index 0.8295).<\/p>\n

\"\"<\/p>\n

Effect 2<\/strong> is the donation of a lone pair from sulfur S3 or S7 into the antibonding orbital of the S1-S2 bond with length 2.087Å. Only one donation – E(2) is now 10.12 kcal\/mol – for each of the two S-S antibonding orbitals occurs (S1-S2 and S4-S5) and hence the lengthening of these is less than before. This again serves to shorten the S2-S3 and S4-S7 bonds labelled with the distance of 1.982Å<\/p>\n

\"\"<\/p>\n

A smaller effect (E(2) 4.6 kcal\/mol) occurs between S2\/S4 and S1-S6\/S5-S6. <\/p>\n

So this adds a nice stereoelectronic explanation to an observation made almost 50 years ago. Perhaps this example should be included in all taught inorganic curricula? <\/p>\n

\n

Postscript:<\/b> The S-S stretching frequencies vary a great deal. The symmetric and antisymmetric S2-S3 and S4-S7 modes are respectively ν 564 and 557 cm-1<\/sup> whilst the S3-S7 mode is way less at 370 cm-1<\/sup><\/p>\n

\n

Postscript 1:<\/b> The smaller S5<\/sub> ring also shows this effect, but to a smaller extent (E(2) = 6.1 kcal\/mol) and νS1-S2 = 382 vs 546 and 540cm-1<\/sup><\/p>\n

\"\"<\/p>\n

Also for fun, how about singlet state cyclo-O7<\/sub> (heptaoxolane)? Unsurprisingly, the anomeric effects noted for S7<\/sub> itself are amplified to the point that the molecule dissociates to O3<\/sub> and 2O2<\/sub> (singlet).<\/p>\n

\"\"<\/p>\n

Finally, singlet state cyclo-O5<\/sub> (pentaoxolane)
\n\"\"<\/p>\n

Here νO-O<\/sub> cover the remarkable range from 1519, 1101, 953, 227 to 200 cm-1<\/sup> (purple values in diagram above)<\/p>\n

These vibrations are associated with the following NBO E(2) Energies; O2Lp<\/sub>-O3O4σ*<\/sub> 34.1, O2Lp<\/sub>-O1O5σ*<\/sub> 23.3, O4Lp<\/sub>-O1O5σ*<\/sub> 20.7, O5Lp<\/sub>-O3O4σ*<\/sub> 19.9, O1Lp<\/sub>-O2O3σ*<\/sub> 12.1, O3Lp<\/sub>-O1O2σ*<\/sub> 10.6. <\/p>\n

In addition to these lone pair to σ* interactions, there are two very high σ to σ* interactions (O1O5 to O3O4*<\/sup> 39.9 and O3O4 to O1O5* 33.5 kcal\/mol) which strongly suggest very high so-called multi-reference character to the wavefunction. <\/p>\n

Although not a molecule that is ever likely to be isolated in a laboratory, cyclo-O5<\/sub> still has a lot to teach us.<\/p>\n

\n

Note added April 2026<\/b>: Anomeric effects in linear polysulfide anions such as S8<\/sub>2-<\/sup>[3]<\/a><\/span> were previously noted on this blog[4]<\/a><\/span>.<\/p>\n

References<\/h2>\n
  1. R. Steudel, R. Reinhardt, and F. Schuster, \"Crystal and Molecular Structure of <i>cyclo<\/i>\u2010Heptasulfur (\u03b4\u2010S<sub>7<\/sub>)\", Angewandte Chemie International Edition in English<\/i>, vol. 16, pp. 715-715, 1977. https:\/\/doi.org\/10.1002\/anie.197707151<\/a>\n\n<\/li>\n
  2. H. Rzepa, \"Cyclo-Heptasulfur, S7 \u2013 a classic anomeric effect discovered during a pub lunch!\", 2025. https:\/\/doi.org\/10.14469\/hpc\/15228<\/a>\n\n<\/li>\n
  3. Rybak, W.K.., Cymbaluk, A.., Skonieczny, J.., and Siczek, M.., \"CCDC 880780: Experimental Crystal Structure Determination\", 2012. https:\/\/doi.org\/10.5517\/ccykj88<\/a>\n\n<\/li>\n
  4. H. Rzepa, \"A periodic table for anomeric centres.\", 2016. https:\/\/doi.org\/10.59350\/ae8gx-pqy35<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    Way back in 1977, the crystal structure of the sulfur ring S7 was reported. The authors noted that “The \u03b4 modification of S7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule.” No explanation was offered, although they note that similar effects have been observed in S8O, S7I+ […]<\/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":"federated","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":[1745,4],"tags":[],"ppma_author":[2661],"class_list":["post-28407","post","type-post","status-publish","format-standard","hentry","category-crystal_structure_mining","category-interesting-chemistry"],"yoast_head":"\nCyclo-Heptasulfur, S7 - a classic anomeric effect discovered during a pub lunch! - 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=28407\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Cyclo-Heptasulfur, S7 - a classic anomeric effect discovered during a pub lunch! - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Way back in 1977, the crystal structure of the sulfur ring S7 was reported. The authors noted that “The \u03b4 modification of S7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule.” No explanation was offered, although they note that similar effects have been observed in S8O, S7I+ […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2025-05-16T14:26:48+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-04-05T08:26:49+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=\"5 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Cyclo-Heptasulfur, S7 - a classic anomeric effect discovered during a pub lunch! - 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=28407","og_locale":"en_GB","og_type":"article","og_title":"Cyclo-Heptasulfur, S7 - a classic anomeric effect discovered during a pub lunch! - Henry Rzepa's Blog","og_description":"Way back in 1977, the crystal structure of the sulfur ring S7 was reported. The authors noted that “The \u03b4 modification of S7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule.” No explanation was offered, although they note that similar effects have been observed in S8O, S7I+ […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407","og_site_name":"Henry Rzepa's Blog","article_published_time":"2025-05-16T14:26:48+00:00","article_modified_time":"2026-04-05T08:26:49+00:00","author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"5 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"Cyclo-Heptasulfur, S7 – a classic anomeric effect discovered during a pub lunch!","datePublished":"2025-05-16T14:26:48+00:00","dateModified":"2026-04-05T08:26:49+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407"},"wordCount":698,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2025\/05\/S7.jpg","articleSection":["crystal_structure_mining","Interesting chemistry"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407","name":"Cyclo-Heptasulfur, S7 - a classic anomeric effect discovered during a pub lunch! - 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=28407#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2025\/05\/S7.jpg","datePublished":"2025-05-16T14:26:48+00:00","dateModified":"2026-04-05T08:26:49+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=28407#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#primaryimage","url":"","contentUrl":""},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28407#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"Cyclo-Heptasulfur, S7 – a classic anomeric effect discovered during a pub lunch!"}]},{"@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\/pDef7-7ob","jetpack-related-posts":[{"id":28515,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28515","url_meta":{"origin":28407,"position":0},"title":"Cycloheptasulfur sulfoxide, S7O – Anomeric effects galore!","author":"Henry Rzepa","date":"May 19, 2025","format":false,"excerpt":"The monosulfoxide of cyclo-heptasulfur was reported along with cycloheptasulfur itself in 1977, along with the remarks that \"The \u03b4 modification of S7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule. and \"the same effect having also been observed in other sulfur rings\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":28615,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615","url_meta":{"origin":28407,"position":1},"title":"5-Imino-5\u03bb4-heptathiepane 3-oxide. More exuberent anomeric effects.","author":"Henry Rzepa","date":"May 20, 2025","format":false,"excerpt":"The two previous \u00a0posts, on the topic of anomeric effects in 7-membered sulfur rings illustrated how orbital interactions between the lone pairs in the molecules and S-S bonds produced widely varying S-S bond lengths in the molecules, some are shorter than normal (which is ~2.05\u00c5 for e.g. the S8 ring)\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":28639,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28639","url_meta":{"origin":28407,"position":2},"title":"S7I1+: The largest anomeric effect exhibited by sulfur.","author":"Henry Rzepa","date":"May 21, 2025","format":false,"excerpt":"In this series of posts about the electronic effects in small sulfur rings I have explored increasingly large induced geometric effects. Here is the largest so far, for the compound S7I1+ The calculated geometry is shown below, with the crystallographic values in parentheses - the two matching very well. The\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":26962,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=26962","url_meta":{"origin":28407,"position":3},"title":"Detecting anomeric effects in tetrahedral boron bearing four oxygen substituents.","author":"Henry Rzepa","date":"April 30, 2024","format":false,"excerpt":"In an earlier post, I discussed a phenomenon known as the \"anomeric effect\" exhibited by tetrahedral carbon compounds with four C-O bonds. Each oxygen itself bears two bonds and has two lone pairs, and either of these can align with one of three other C-O bonds to generate an anomeric\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":16696,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16696","url_meta":{"origin":28407,"position":4},"title":"A periodic table for anomeric centres, this time with quantified interactions.","author":"Henry Rzepa","date":"August 8, 2016","format":false,"excerpt":"The previous post contained an exploration of the anomeric effect as it occurs at an atom centre X for which the effect is manifest in crystal structures. Here I\u00a0quantify the effect, by selecting the test molecule MeO-X-OMe, where X is of two types:A two-coordinate atom across the series B-O 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":16646,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16646","url_meta":{"origin":28407,"position":5},"title":"Stereoelectronic effects galore: bis(trifluoromethyl)trioxide.","author":"Henry Rzepa","date":"August 4, 2016","format":false,"excerpt":"Here is a little molecule that can be said to be pretty electron rich. There are lots of lone pairs present, and not a few electron-deficient \u03c3-bonds. I thought it might be fun to look at the stereoelectronic interactions set up in this little system. Known as ZEYDOW in the\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":"","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\/28407","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=28407"}],"version-history":[{"count":100,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28407\/revisions"}],"predecessor-version":[{"id":31138,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28407\/revisions\/31138"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28407"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28407"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28407"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=28407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}