{"id":14016,"date":"2015-05-12T18:10:36","date_gmt":"2015-05-12T17:10:36","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=14016"},"modified":"2023-09-16T18:27:20","modified_gmt":"2023-09-16T17:27:20","slug":"the-burgi-dunitz-angle-revisited-a-mystery","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016","title":{"rendered":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery?"},"content":{"rendered":"
\n

\n\tThe Bürgi–Dunitz<\/a> angle is one of those memes that most students of organic chemistry remember. It hypothesizes the geometry of attack of a nucleophile<\/a> on a trigonal unsaturated (sp2<\/sup>) carbon in a molecule such as ketone, aldehyde, ester, and amide carbonyl. Its value obviously depends on the exact system, but is generally taken to be in the range 105-107°. A very good test of this approach is to search the crystal structure database (this was how it was originally established[1]<\/a><\/span>).\n<\/p>\n

\n\t\"search-BD\"<\/a>The search is defined as follows\n<\/p>\n

    \n
  1. \n\t\tR can be either H or C\n\t<\/li>\n
  2. \n\t\tThe carbon is constrained to 3-coordinate\n\t<\/li>\n
  3. \n\t\tThe carbonyl oxygen is constrained to 1-coordinate\n\t<\/li>\n
  4. \n\t\tQA can be any of N, O, S, Cl, F.\n\t<\/li>\n
  5. \n\t\tQB can be any of H (aldehyde), C (ketone), N (amide), O (ester) or S (thioester).\n\t<\/li>\n
  6. \n\t\tThe distance QA…C is constrained to any intermolecular non-bonded contact<\/em><\/strong> ≤ the sum of the van der Waals radii of the two atoms involved and the angle QA…C=O is the Bürgi–Dunitz angle.\n\t<\/li>\n
  7. \n\t\tI have also added a torsion constraint to specify that Nu has got to be ± 20° from orthogonality to the plane of the carbonyl to allow it to attack the π* orbital.\n\t<\/li>\n
  8. \n\t\tThe crystallographic R factor must be < 0.05, no disorder, no crystallographic errors and the temperature is either any or < 120K.\n\t<\/li>\n<\/ol>\n

    \n\tWith no temperature specified, 6994 hits are obtained as below. So the most probable angle (red spot) is ~90°.\n<\/p>\n

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

    \n\tOne important change to the search is to decrease the temperature to 120K, since structures will have less vibrational noise. The number of hits decreases to 1279, but the most probable angle if anything reduces slightly.\n<\/p>\n

    \n\t\"BD-120K\"<\/a>\n<\/p>\n

    \n\tSo we have something of a mystery; this crystallographic data shows an angle of approach about 15° less than the oft quoted value. Here are some thoughts:\n<\/p>\n

      \n
    1. \n\t\tThis search is the average for all types of carbonyl, whereas the original suggestion was constrained to four types of nucleophiles and simple ketones.\n\t<\/li>\n
    2. \n\t\tThis search extends the interacting distance of the nucleophile and the carbon out to 3.5Å which is significantly longer than the normally considered length of ~2.85Å. The hotspots occur at about 3.15Å and not 2.85Å.\n\t<\/li>\n
    3. \n\t\tThere is obviously considerably more data available in 2015 than in 1974, and in particular at low temperature.\n\t<\/li>\n
    4. \n\t\tThe Bürgi–Dunitz angle is in fact one of two defining the trajectory, the other being the Flippin–Lodge angle<\/a> which defines the displacement towards R or QB. The search above gives no direct information about this angle, but the torsion is related since it is constrained to bisect the C=O to within ± 20° and hence bisect the groups R and QB.\n\t<\/li>\n
    5. \n\t\tAn angle of ≤ 90° does not match to the normal explanation, which is that the nucleophile attacks the π* orbital, each lobe of which "leans out<\/a>" from the centre at about 105° rather than leaning in at ≤ 90°.\n\t<\/li>\n
    6. \n\t\tDecreasing the torsion range to  ± 5° at 120K gives 592 hits with a hot spot at 95°\n\t<\/li>\n
    7. \n\t\tAlso constraining the distance QA…C to be 0.3Å less than the van der Waals sum at 120K gives 59 hits with a hot spot at 95° and 2.9Å.\n\t<\/li>\n<\/ol>\n

      \n\tWell, to get to the bottom of this will require reducing the scope of both QA and QB, to find which if any of discrete values for these two variables can indeed give an angle of 105-107°. This would make for quite a good student group project; I expect a group of 8 students could sort this out quite quickly!\n<\/p>\n

      \n

      Acknowledgments<\/h4>\n

      This post has been cross-posted in PDF format at Authorea<\/a>.<\/p>\n

      References<\/h2>\n
      1. H. B:urgi, J. Dunitz, J. Lehn, and G. Wipff, \"Stereochemistry of reaction paths at carbonyl centres\", Tetrahedron<\/i>, vol. 30, pp. 1563-1572, 1974. https:\/\/doi.org\/10.1016\/s0040-4020(01)90678-7<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

        The Bürgi–Dunitz angle is one of those memes that most students of organic chemistry remember. It hypothesizes the geometry of attack of a nucleophile on a trigonal unsaturated (sp2) carbon in a molecule such as ketone, aldehyde, ester, and amide carbonyl. Its value obviously depends on the exact system, but is generally taken to be in the range 105-107°. A very good test of this approach […]<\/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":[2,1745],"tags":[663,1430,1427,1395,1412,1394,1428,1410,1413,1429],"ppma_author":[2661],"class_list":["post-14016","post","type-post","status-publish","format-standard","hentry","category-chemical-it","category-crystal_structure_mining","tag-alkene","tag-burgi-dunitz-angle","tag-carbonyl","tag-chemistry","tag-functional-groups","tag-group-of-eight","tag-ketone","tag-organic-chemistry","tag-organic-compounds","tag-stall"],"yoast_head":"\nThe B\u00fcrgi\u2013Dunitz angle revisited: a mystery? - 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=14016\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery? - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"The Bürgi–Dunitz angle is one of those memes that most students of organic chemistry remember. It hypothesizes the geometry of attack of a nucleophile on a trigonal unsaturated (sp2) carbon in a molecule such as ketone, aldehyde, ester, and amide carbonyl. Its value obviously depends on the exact system, but is generally taken to be in the range 105-107°. A very good test of this approach […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2015-05-12T17:10:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-09-16T17:27:20+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg\" \/>\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":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery? - 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=14016","og_locale":"en_GB","og_type":"article","og_title":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery? - Henry Rzepa's Blog","og_description":"The Bürgi–Dunitz angle is one of those memes that most students of organic chemistry remember. It hypothesizes the geometry of attack of a nucleophile on a trigonal unsaturated (sp2) carbon in a molecule such as ketone, aldehyde, ester, and amide carbonyl. Its value obviously depends on the exact system, but is generally taken to be in the range 105-107°. A very good test of this approach […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016","og_site_name":"Henry Rzepa's Blog","article_published_time":"2015-05-12T17:10:36+00:00","article_modified_time":"2023-09-16T17:27:20+00:00","og_image":[{"url":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg","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=14016#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery?","datePublished":"2015-05-12T17:10:36+00:00","dateModified":"2023-09-16T17:27:20+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016"},"wordCount":642,"commentCount":3,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg","keywords":["alkene","B\u00fcrgi\u2013Dunitz angle","Carbonyl","Chemistry","Functional groups","Group of Eight","Ketone","Organic chemistry","Organic compounds","Stall"],"articleSection":["Chemical IT","crystal_structure_mining"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016","name":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery? - 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=14016#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg","datePublished":"2015-05-12T17:10:36+00:00","dateModified":"2023-09-16T17:27:20+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=14016#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016#primaryimage","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg","contentUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/05\/search-BD.jpg","width":748,"height":534},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14016#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"The B\u00fcrgi\u2013Dunitz angle revisited: a mystery?"}]},{"@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\/pDef7-3E4","jetpack-related-posts":[{"id":16361,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16361","url_meta":{"origin":14016,"position":0},"title":"What is the approach trajectory of enhanced (super?) nucleophiles towards a carbonyl group?","author":"Henry Rzepa","date":"May 11, 2016","format":false,"excerpt":"I have previously commented on the B\u00fcrgi\u2013Dunitz angle, this being the preferred approach trajectory of a nucleophile towards the electrophilic carbon of a carbonyl group. Some special types of nucleophile such as hydrazines (R2N-NR2) are supposed to have enhanced reactivity due to what might be described as\u00a0buttressing of adjacent lone\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":12678,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=12678","url_meta":{"origin":14016,"position":1},"title":"Amides and inverting the electronics of the B\u00fcrgi\u2013Dunitz trajectory.","author":"Henry Rzepa","date":"June 26, 2014","format":false,"excerpt":"The B\u00fcrgi\u2013Dunitz angle describes the trajectory of an approaching nucleophile towards the carbon atom of a carbonyl group. A colleague recently came to my office to ask about the inverse, that is what angle would an electrophile approach (an amide)? Thus it might approach either syn or\u00a0anti\u00a0with respect to 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":[]},{"id":13688,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13688","url_meta":{"origin":14016,"position":2},"title":"Mechanism of the Lithal (LAH) reduction of cinnamaldehyde.","author":"Henry Rzepa","date":"April 1, 2015","format":false,"excerpt":"The reduction of cinnamaldehyde by lithium aluminium hydride (LAH) was reported in a classic series of experiments,, dating from 1947-8. The reaction was first introduced into the organic chemistry laboratories here at Imperial College decades ago, vanished for a short period, and has recently been reintroduced again.\u2021 The experiment is\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":14423,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14423","url_meta":{"origin":14016,"position":3},"title":"Intermolecular atom-atom bonds in crystals? The O…O case.","author":"Henry Rzepa","date":"July 25, 2015","format":false,"excerpt":"I recently followed this bloggers trail; link1 \u2192 link2 to arrive at this delightful short commentary on atom-atom bonds in crystals by Jack Dunitz. Here he discusses that age-old question (to chemists), what is a bond? Even almost 100 years after Gilbert Lewis' famous analysis, we continue to ponder this\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":"OO-query","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/07\/OO-query.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":6874,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6874","url_meta":{"origin":14016,"position":4},"title":"Transition state models for Baldwin’s rules of ring closure.","author":"Henry Rzepa","date":"June 2, 2012","format":false,"excerpt":"The Baldwin rules for ring closure follow the earlier ones by B\u00fcrgi and Dunitz\u00a0in stating the preferred angles of nucleophilic (and electrophilic) attack in bond forming reactions, and are as famous for the interest in their exceptions as for their adherence. Both sets of rules fundamentally explore the geometry of\u2026","rel":"","context":"In "General"","block_context":{"text":"General","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1"},"img":{"alt_text":"","src":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/06\/baldwin.svg","width":350,"height":200},"classes":[]},{"id":14161,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14161","url_meta":{"origin":14016,"position":5},"title":"The formation of tetrahedral intermediates.","author":"Henry Rzepa","date":"June 12, 2015","format":false,"excerpt":"In the preceding post, I discussed\u00a0the reaction between mCPBA (meta-chloroperbenzoic acid) and cyclohexanone, resulting in Baeyer-Villiger oxidation via a tetrahedral intermediate (TI). Dan Singleton, in whose group the original KIE (kinetic isotope measurements) were made, has kindly\u00a0pointed out\u00a0on this blog that his was a mixed-phase reaction, and that mechanistic comparison\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"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\/14016","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=14016"}],"version-history":[{"count":9,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/14016\/revisions"}],"predecessor-version":[{"id":26471,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/14016\/revisions\/26471"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14016"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14016"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14016"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=14016"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}