{"id":19436,"date":"2018-02-24T17:09:52","date_gmt":"2018-02-24T17:09:52","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=19436"},"modified":"2018-03-04T08:05:14","modified_gmt":"2018-03-04T08:05:14","slug":"hypervalent-or-not-a-fluxional-triselenide","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436","title":{"rendered":"Hypervalent or not? A fluxional triselenide."},"content":{"rendered":"
\n

Another post inspired by a comment<\/a> on an earlier one<\/a>; I had been discussing compounds of the type I.In<\/sub> (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989.[1]<\/a><\/span><\/p>\n

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

This compound was investigated using 77<\/sup>Se NMR, with the following conclusions:<\/p>\n

    \n
  1. The compound is fluxional, with the lines at room temperature broadened compared to those at -50\u00b0C.<\/li>\n
  2. At -50\u00b0C the peaks are sharp enough to discern 1<\/sup>JSe-Se<\/sub> couplings, with multiplicities and integrations that suggest a central Se is surrounded by four equivalent further Se atoms, with shifts of 655.1 and 251.2 ppm.<\/li>\n
  3. The magnitude of this 1<\/sup>JSe-Se<\/sub> coupling (391 Hz) leads to the suggestion of a considerable contribution of a resonance form with Se=Se bonds (structure 2<\/strong> above).<\/li>\n
  4. This was supported by 2<\/sup>J13C-77Se<\/sub> couplings which also imply a symmetrically coordinated central \u00a0Se.<\/li>\n
  5. Thus the two resonance forms 1<\/strong> or 2<\/strong> above were suggested as the predominant form at -50\u00b0C, with an increasing incursion of the open chain isomer\u00a03<\/strong> at higher temperatures giving rise to the observed fluxional dynamic behaviour.<\/li>\n
  6. One may surmise from these results that the central Se is certainly hypercoordinated and by the classical interpretations hypervalent.<\/li>\n<\/ol>\n

    Here are some calculations (R=H), at the\u00a0\u03c9B97XD\/Def2-TZVPP\/SCRF=chloroform level.\u2021\u00a0<\/sup>In red are the calculated Wiberg Se-Se bond orders, which give little indication of any Se=Se double bond character.\u00a0<\/p>\n

    \"\"<\/p>\n

    The calculated 77<\/sup>Se shifts are shown in magenta, with the observed values being 655 and 255 ppm. The match is not good, the errors were 120 and 20.5 ppm.\u2020<\/sup>\u00a0 However calculated shifts for elements adjacent to e.g.<\/em> Se or Br etc suffer from relativistic effects such as spin orbit coupling.[2]<\/a><\/span> Thus the shift for the central Se, surrounded by four other Se atoms is likely to have a significant error, but the error for the four other Se atoms should be less. The reverse is true.<\/p>\n

    However, all the calculations of this species (up to Def2-TZVPPD basis set) showed this symmetric form of D2h<\/sub> symmetry to actually be a transition state, as per below. \"\"<\/p>\n

    There is a minimum with the structure below in which one pair of Se-Se lengths are longer than the other pair and for which the free energy is 6.5 kcal\/mol lower. The Wiberg bond orders for the two sets of Se-Se bonds are now 0.16 and 0.86, which very much corresponds to structure 3<\/strong> above.<\/p>\n

    \"\"<\/p>\n

    Assuming that this compound is fluxional even at -50\u00b0C, the average of the pairs of Se atoms gives calculated shifts of 667 ppm (655 obs) whilst the central Se is 204.6 ppm (251 obs). The latter, influenced by two especially short Se-Se distances, is likely to have a very large spin-orbit coupling error, whilst for the former the error will be smaller (13<\/sup>C shifts adjacent to one Br typically have induced calculated errors of about 14 ppm[2]<\/a><\/span>).<\/p>\n

    At this point I searched the Cambridge structure database for Se coordinated by four other Se atoms. A close analogue[3]<\/a><\/span> has the structure shown below, in which pairs of Se-Se interactions have unequal bond lengths, the shorter being ~2.45\u00c5. This matches the calculation above reasonably well.<\/p>\n

    \"\"<\/p>\n

    Reconciling these various observations, we might assume that even at\u00a0-50\u00b0C the fluxional behaviour has not been frozen out. Given that the fluxional barrier is only 6.5 kcal\/mol, it is unlikely that the spectrum could be measured at a sufficiently low temperature to reveal not two sets of Se signals in the ratio 4:1 but three in the ratio 2:2:1. The spin-spin couplings reported presumably are a result of averaging a genuine\u00a01<\/sup>JSe-Se<\/sub> coupling with a through space coupling.<\/p>\n

    So it appears that the analysis of the\u00a077<\/sup>Se NMR reported in this article [1]<\/a><\/span> may not be quite what it seems. A better interpretation is that structure 3<\/strong> is the most realistic. This means no hypercoordination for the Se, never mind hypervalence!<\/p>\n

    \n

    \u2021<\/sup>FAIR data at DOI: 10.14469\/hpc\/3724<\/a>. \u2020<\/sup>The original reference, Me2<\/sub>Se was incorrectly calculated without solvation by chloroform. The values shown here are now corrected from those shown in the original post.<\/p>\n

    References<\/h2>\n
    1. Y. Mazaki, and K. Kobayashi, \"Structure and intramolecular dynamics of bis(diisobutylselenocarbamoyl) triselenide as identified in solution by the 77Se-NMR spectroscopy\", Tetrahedron Letters<\/i>, vol. 30, pp. 2813-2816, 1989. https:\/\/doi.org\/10.1016\/s0040-4039(00)99132-9<\/a>\n\n<\/li>\n
    2. D.C. Braddock, and H.S. Rzepa, \"Structural Reassignment of Obtusallenes V, VI, and VII by GIAO-Based Density Functional Prediction\", Journal of Natural Products<\/i>, vol. 71, pp. 728-730, 2008. https:\/\/doi.org\/10.1021\/np0705918<\/a>\n\n<\/li>\n
    3. R.O. Gould, C.L. Jones, W.J. Savage, and T.A. Stephenson, \"Crystal and molecular structure of bis(NN-diethyldiselenocarbamato)-selenium(II)\", Journal of the Chemical Society, Dalton Transactions<\/i>, pp. 908, 1976. https:\/\/doi.org\/10.1039\/dt9760000908<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

      Another post inspired by a comment on an earlier one; I had been discussing compounds of the type I.In (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989. This compound was investigated using 77Se NMR, with the following conclusions: The compound is fluxional, […]<\/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":[7],"tags":[182,557,1395,40,1679,1431,1630,1871,1885],"ppma_author":[2661],"class_list":["post-19436","post","type-post","status-publish","format-standard","hentry","category-hypervalency","tag-c","tag-chemical-bonding","tag-chemistry","tag-free-energy","tag-hypervalent-molecule","tag-matter","tag-molecular-geometry","tag-nature","tag-nitrogen"],"yoast_head":"\nHypervalent or not? A fluxional triselenide. - 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=19436\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Hypervalent or not? A fluxional triselenide. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Another post inspired by a comment on an earlier one; I had been discussing compounds of the type I.In (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989. This compound was investigated using 77Se NMR, with the following conclusions: The compound is fluxional, […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2018-02-24T17:09:52+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2018-03-04T08:05:14+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.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":"Hypervalent or not? A fluxional triselenide. - 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=19436","og_locale":"en_GB","og_type":"article","og_title":"Hypervalent or not? A fluxional triselenide. - Henry Rzepa's Blog","og_description":"Another post inspired by a comment on an earlier one; I had been discussing compounds of the type I.In (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989. This compound was investigated using 77Se NMR, with the following conclusions: The compound is fluxional, […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436","og_site_name":"Henry Rzepa's Blog","article_published_time":"2018-02-24T17:09:52+00:00","article_modified_time":"2018-03-04T08:05:14+00:00","og_image":[{"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.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=19436#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"Hypervalent or not? A fluxional triselenide.","datePublished":"2018-02-24T17:09:52+00:00","dateModified":"2018-03-04T08:05:14+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436"},"wordCount":691,"commentCount":3,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.svg","keywords":["C","chemical bonding","Chemistry","free energy","Hypervalent molecule","Matter","Molecular geometry","Nature","Nitrogen"],"articleSection":["Hypervalency"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436","name":"Hypervalent or not? A fluxional triselenide. - 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=19436#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.svg","datePublished":"2018-02-24T17:09:52+00:00","dateModified":"2018-03-04T08:05:14+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=19436#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436#primaryimage","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.svg","contentUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2018\/02\/Se-page001.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19436#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"Hypervalent or not? A fluxional triselenide."}]},{"@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\/pDef7-53u","jetpack-related-posts":[{"id":1103,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1103","url_meta":{"origin":19436,"position":0},"title":"Hypervalency: a reality check","author":"Henry Rzepa","date":"October 5, 2009","format":false,"excerpt":"We have seen in the series of posts on the topic of hypervalency\u00a0how the first row main group elements such as\u00a0Be, B, C and N can sustain apparent hypercoordination and arguably hypervalency. The latter is defined not so much by expanding the total valence shell of electrons surrounding the hypervalent\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"YOCVIV: Crystal structure of hexacoordinate boron","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/BBr.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":19279,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19279","url_meta":{"origin":19436,"position":1},"title":"Can any hypervalence in diazomethanes be amplified?","author":"Henry Rzepa","date":"December 23, 2017","format":false,"excerpt":"In the previous post, I referred to a recently published review on hypervalency which introduced a very simple way (the\u00a0valence electron equivalent \u03b3)\u00a0of quantifying the effect.\u00a0Diazomethane was cited as one example of a small molecule exhibiting hypervalency (on nitrogen) by this measure. Here I explore the effect of substituting diazomethane\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":19194,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19194","url_meta":{"origin":19436,"position":2},"title":"Identification of a simplest hypervalent hydrogen fluoride anion.","author":"Henry Rzepa","date":"December 8, 2017","format":false,"excerpt":"An article with the title shown above in part recently appeared. Given the apparent similarity of HF1- to CH3F1- and CH3F2-, the latter of which I introduced on this blog previously,\u00a0I thought it of interest to apply my analysis to HF1-. The authors conclude that \"the F atom of HF\u2212\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":783,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=783","url_meta":{"origin":19436,"position":3},"title":"Capturing penta-coordinate carbon! (Part 1).","author":"Henry Rzepa","date":"September 22, 2009","format":false,"excerpt":"The bimolecular nucleophilic substitution reaction at saturated carbon is an icon of organic chemistry, and is better known by its mechanistic label, SN2. It is normally a slow reaction, with half lives often measured in hours. This implies a significant barrier to reaction (~15-20 kcal\/mol) for the transition state, shown\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":19383,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19383","url_meta":{"origin":19436,"position":4},"title":"Hypervalent Helium – not!","author":"Henry Rzepa","date":"February 16, 2018","format":false,"excerpt":"Last year, this article attracted a lot of attention as the first example of molecular helium in the form of Na2He. In fact, the helium in this species has a calculated\u2021 bond index of only 0.15 and it is better classified as a sodium electride with the ionisation induced by\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":18975,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=18975","url_meta":{"origin":19436,"position":5},"title":"Hypervalence revisited. The odd case of hexamethyl selenium.","author":"Henry Rzepa","date":"November 7, 2017","format":false,"excerpt":"One thread that runs through this blog is that of hypervalency. It was therefore nice to come across a recent review of the concept which revisits the topic, and where a helpful summary is given of the evolving meanings over time of the term hypervalent. The key phrase \"it soon\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/11\/165-1024x1008.jpg?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\/19436","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=19436"}],"version-history":[{"count":22,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/19436\/revisions"}],"predecessor-version":[{"id":19475,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/19436\/revisions\/19475"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19436"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19436"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=19436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}