{"id":22881,"date":"2020-11-02T12:40:53","date_gmt":"2020-11-02T12:40:53","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=22881"},"modified":"2020-11-02T12:47:07","modified_gmt":"2020-11-02T12:47:07","slug":"trimerous-pericyclic-reactions-what-is-the-effect-of-changing-the-electron-count-by-two","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881","title":{"rendered":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two?"},"content":{"rendered":"
\n

In an earlier post<\/a>, I pondered on how the “arrow pushing” for the thermal pericyclic reactions of some annulenes (cyclic conjugated hydrocarbons) could be represented in terms of either two separate electrocyclic reactions or of one cycloaddition reaction. Each reaction is governed by selection rules<\/b> which can be stated in terms of the anticipated aromaticity of the pericyclic transition state as belonging to a 4n<\/b> or a 4n+2<\/b> class. This in turn determines whether the topology of the transition state belongs to a class of aromatic species known as either H\u00fcckel or M\u00f6bius. Here I play with the observation that by adding or removing two electrons from the molecule, the two classes 4n<\/b>\u00a0and\u00a04n+2<\/b>\u00a0can be swapped. What happens to the aromaticities of the transition states if that is done?<\/p>\n

The test bed is a [20]annulene, which might undertake either a eight electron (4n) 4s<\/sub>+4s<\/sub> cycloaddition in the inner ring, or two eight electron (4n) electrocyclic reactions in the outer rings in which the new bond is formed antarafacially from opposite faces. The selection rules suggest that the former must proceed through an anti or non-aromatic H\u00fcckel transition state and the latter through an aromatic M\u00f6bius transition state.<\/p>\n

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

We are measuring the aromaticity by using the so-called NICS NMR method, for which an aromatic value is a negative chemical shift for the NICS probe, a non-aromatic value is ~0 and an anti-aromatic value a positive chemical shift. The location of these probes is determined by analysis of the critical points in the electron density of the transition states and placement at either the ring or the cage critical point so determined.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
#<\/th>\nSystem<\/th>\nCharge<\/th>\n\u03bd(s)<\/th>\n\u03bd(a)<\/th>\nNICS (outer rings)<\/th>\nNICS (inner ring)<\/th>\n\u0394G<\/th>\nDOI<\/th>\n<\/tr>\n
1<\/td>\ntrans, D2<\/sub><\/td>\n0<\/td>\n-399<\/td>\n-433<\/td>\n-6.7<\/td>\n-0.3<\/td>\n-774.036424<\/td>\n7483<\/a><\/td>\n<\/tr>\n
2<\/td>\ntrans, D2<\/sub><\/td>\n+2<\/td>\n-388<\/td>\n-399<\/td>\n+4.0<\/td>\n+2.1<\/td>\n-773.381567<\/td>\n7490<\/a><\/td>\n<\/tr>\n
3<\/td>\ntrans, D2<\/sub><\/td>\n-2<\/td>\n-412<\/td>\n-324<\/td>\n-15.0<\/td>\n-12.9<\/td>\n-774.179873<\/td>\n7526<\/a><\/td>\n<\/tr>\n
4<\/td>\ncis, Cs<\/td>\n0<\/td>\n-413<\/td>\n-369<\/td>\n-8.6<\/td>\n-5.4<\/td>\n-774.048172<\/td>\n7482<\/a><\/td>\n<\/tr>\n
5<\/td>\ncis, Cs<\/td>\n+2<\/td>\n-640<\/td>\n-453<\/td>\n+11.1<\/td>\n+2.1<\/td>\n-773.386424<\/td>\n7493<\/a><\/td>\n<\/tr>\n
6<\/td>\ncis, C2<\/sub><\/td>\n0<\/td>\n-491<\/td>\n-459<\/td>\n-8.3<\/td>\n+1.4<\/td>\n-774.059141<\/td>\n7486<\/a><\/td>\n<\/tr>\n
7<\/td>\ncis, C2<\/sub><\/td>\n+2<\/td>\n-685<\/td>\n-479<\/td>\n+10.5<\/td>\n+2.3\/+3.7<\/td>\n-773.392100<\/td>\n7497<\/a><\/td>\n<\/tr>\n
8<\/td>\ncis, C2<\/sub><\/td>\n-2<\/td>\n-926<\/td>\n-533<\/td>\n+8.4<\/td>\n-13.9<\/td>\n-774.2029900<\/td>\n7525<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Each of the stationary points located is in fact a saddle point of order 2 (and in some cases 3), with \u03bd(s) corresponding to normal vibrational mode for synchronous formation of both bonds, and \u03bd(a) to formation of one C-C bond but cleavage of the other. The fact that both the force constants for these modes are negative suggests that the two electrocyclic reactions are independent and occur consecutively rather than concurrently. This then argues against it being a synchronous cycloaddition reaction, but could of course still be a highly asynchronous one.<\/p>\n

The first three examples are in fact for a [20]annulene with a central trans<\/em> rather than cis<\/em> double bond (as illustrated above), resulting in D2<\/sub> symmetry. The neutral system has the outer ring aromatic (-ve NICS) and the inner ring non-aromatic, as appropriate for the rules stated above. Removing two electrons might you would imagine swap these two, but of course the electrons are removed from the entire [20]annulene as a whole, and not from specific regions. In fact it results in mildly anti-aromatic rings in both regions. Adding two electrons now makes the rings strongly aromatic, behaving as if the two electrons have really only modified the inner cycloaddition reaction.<\/p>\n

The reactions with a cis<\/em> stereochemistry at the central bond again confirm for the rules for the neutral annulene, but now the dianion predicts the outer ring to be anti-aromatic and the inner one aromatic, with a reversal of aromaticity for both<\/strong> sets of rings. Despite the cycloaddition now being an aromatic transition state, the force constants still indicate it to be asynchronous. But the observation that \u03bd(s) is now significantly larger than \u03bd(a) suggests that perhaps the reaction can indeed now be considered as at least in part an asymmetric cycloaddition.\u00a0<\/p>\n

\"\"

Click to view vibrational modes<\/p><\/div>\n

What is the point of doing these calculations, you may well ask? Its unlikely that they could ever be subjected to experimental tests! Well, here we are using quantum mechanical calculations as an experimental procedure in its own right, to try to push the simple pericyclic selection rules beyond anything envisaged by its original formulators.<\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

In an earlier post, I pondered on how the “arrow pushing” for the thermal pericyclic reactions of some annulenes (cyclic conjugated hydrocarbons) could be represented in terms of either two separate electrocyclic reactions or of one cycloaddition reaction. Each reaction is governed by selection rules which can be stated in terms of the anticipated aromaticity […]<\/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":[559],"tags":[],"ppma_author":[2661],"class_list":["post-22881","post","type-post","status-publish","format-standard","hentry","category-pericyclic"],"yoast_head":"\nTrimerous pericyclic reactions: what is the effect of changing the electron count by two? - 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=22881\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Trimerous pericyclic reactions: what is the effect of changing the electron count by two? - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"In an earlier post, I pondered on how the “arrow pushing” for the thermal pericyclic reactions of some annulenes (cyclic conjugated hydrocarbons) could be represented in terms of either two separate electrocyclic reactions or of one cycloaddition reaction. Each reaction is governed by selection rules which can be stated in terms of the anticipated aromaticity […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2020-11-02T12:40:53+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2020-11-02T12:47:07+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.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=\"3 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two? - 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=22881","og_locale":"en_GB","og_type":"article","og_title":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two? - Henry Rzepa's Blog","og_description":"In an earlier post, I pondered on how the “arrow pushing” for the thermal pericyclic reactions of some annulenes (cyclic conjugated hydrocarbons) could be represented in terms of either two separate electrocyclic reactions or of one cycloaddition reaction. Each reaction is governed by selection rules which can be stated in terms of the anticipated aromaticity […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881","og_site_name":"Henry Rzepa's Blog","article_published_time":"2020-11-02T12:40:53+00:00","article_modified_time":"2020-11-02T12:47:07+00:00","og_image":[{"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.svg","type":"","width":"","height":""}],"author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two?","datePublished":"2020-11-02T12:40:53+00:00","dateModified":"2020-11-02T12:47:07+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881"},"wordCount":712,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.svg","articleSection":["pericyclic"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881","name":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two? - 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=22881#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.svg","datePublished":"2020-11-02T12:40:53+00:00","dateModified":"2020-11-02T12:47:07+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=22881#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#primaryimage","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.svg","contentUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/trimerous.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22881#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"Trimerous pericyclic reactions: what is the effect of changing the electron count by two?"}]},{"@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\/pDef7-5X3","jetpack-related-posts":[{"id":22774,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22774","url_meta":{"origin":22881,"position":0},"title":"Trimerous pericyclic reactions.","author":"Henry Rzepa","date":"October 8, 2020","format":false,"excerpt":"I occasionally spot an old blog that emerges, if only briefly, as \"trending\". In this instance, only the second blog I ever wrote here, way back in 2009 as a follow up to this article. With something of that age, its always worth revisiting to see if any aspect needs\u2026","rel":"","context":"In "Curly arrows"","block_context":{"text":"Curly arrows","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2327"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/10\/10-1024x671.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":5716,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=5716","url_meta":{"origin":22881,"position":1},"title":"A modern take on pericyclic sigmatropic migrations.","author":"Henry Rzepa","date":"November 29, 2011","format":false,"excerpt":"Another common type of pericyclic reaction is the migration of hydrogen or carbon along a conjugated chain, as in the [1,3] migration of a carbon as shown below. As before, I explore the stereochemistry of the thermal and photochemical reactions. The reaction is known to proceed thermally\u00a0with inversion of configuration\u2026","rel":"","context":"In \"pericyclic\"","block_context":{"text":"pericyclic","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=pericyclic"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/11\/s.gif?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":11830,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=11830","url_meta":{"origin":22881,"position":2},"title":"A simple pericyclic reaction encapsulating the four thermal selection rules.","author":"Henry Rzepa","date":"January 2, 2014","format":false,"excerpt":"As my previous post hints, I am performing my annual spring-clean of lecture notes on pericyclic reactions. Such reactions, and their stereochemistry, are described by a set of selection rules. I am always on the lookout for a simple example which can most concisely summarise these rules. The (hypothetical) one\u2026","rel":"","context":"In "pericyclic"","block_context":{"text":"pericyclic","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=559"},"img":{"alt_text":"12Ca","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2014\/01\/12Ca.gif?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":9,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=9","url_meta":{"origin":22881,"position":3},"title":"A Disrotatory 4n+2 electron anti-aromatic M\u00f6bius transition state for a thermal electrocyclic reaction.","author":"Henry Rzepa","date":"April 2, 2009","format":false,"excerpt":"Mauksch and Tsogoeva have recently published an article illustrating how a thermal electrocyclic reaction can proceed with distoratory ring closure, whilst simultaneously also exhibiting 4n electron M\u00f6bius-aromatic character. Why is this remarkable? Because the simple Woodward-Hoffmann rules state that a disrotatory thermal electrocyclic reaction should proceed via a H\u00fcckel-aromatic 4n+2\u2026","rel":"","context":"In "pericyclic"","block_context":{"text":"pericyclic","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=559"},"img":{"alt_text":"Electrocylization of [14] annulene","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/p322.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":8398,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=8398","url_meta":{"origin":22881,"position":4},"title":"Di-imide reduction with a twist: A M\u00f6bius version.","author":"Henry Rzepa","date":"November 26, 2012","format":false,"excerpt":"I was intrigued by one aspect of the calculated transition state for di-imide reduction of an alkene; the calculated NMR shieldings indicated an diatropic ring current at the centre of the ring, but very deshielded shifts for the hydrogen atoms being transferred. This indicated, like most thermal pericyclic reactions, an\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":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/11\/GaussViewScreenSnapz004.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":5632,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=5632","url_meta":{"origin":22881,"position":5},"title":"A modern take on the pericyclic electrocyclic ring opening of cyclobutene.","author":"Henry Rzepa","date":"November 26, 2011","format":false,"excerpt":"Woodward and Hoffmann published their\u00a0milestone article\u00a0 \"Stereochemistry of Electrocyclic Reactions\" in 1965. This brought maturity to the electronic theory of organic chemistry, arguably started by the proto-theory of Armstrong some 75 years earlier. Here, I take a modern look at the archetypal carrier of this insight, the ring opening of\u2026","rel":"","context":"In \"Adam\"","block_context":{"text":"Adam","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=adam"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/11\/con-open.gif?resize=350%2C200","width":350,"height":200},"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\/22881","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=22881"}],"version-history":[{"count":23,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/22881\/revisions"}],"predecessor-version":[{"id":22909,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/22881\/revisions\/22909"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=22881"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=22881"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=22881"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=22881"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}