{"id":1103,"date":"2009-10-05T20:26:26","date_gmt":"2009-10-05T19:26:26","guid":{"rendered":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1103"},"modified":"2009-10-05T21:01:04","modified_gmt":"2009-10-05T20:01:04","slug":"hypervalency-a-reality-check","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1103","title":{"rendered":"Hypervalency: a reality check"},"content":{"rendered":"<div class=\"kcite-section\" kcite-section-id=\"1103\">\n<p>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 atom beyond eight, but in having more than four well defined bonds to it, as quantified by \u00a0AIM and ELF analysis. The previous post made the suggestion of how a compound involving hypervalent boron could also sustain a genuine \u00a0bond to the rare gas helium. It is surely time to seek evidence that this type of bonding can be sustained in reality. Fortunately, a crystal structure of a reasonably analogous compound IS available (DOI: <a href=\"http:\/\/dx.doi.org\/10.1016\/0022-328X(94)05089-T\" target=\"_blank\">10.1016\/0022-328X(94)05089-T<\/a>).<\/p>\n<div id=\"attachment_1106\" style=\"width: 256px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1106\" class=\"size-full wp-image-1106\" title=\"BBr\" onclick=\"jmolInitialize('..\/Jmol\/');jmolSetAppletColor('yellow');jmolApplet([450,450],'load wp-content\/uploads\/2009\/10\/YOCVIV.cif;zoom 120;spin 3;');\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/BBr.jpg\" alt=\"YOCVIV: Crystal structure of hexacoordinate boron\" width=\"246\" height=\"194\" \/><p id=\"caption-attachment-1106\" class=\"wp-caption-text\">YOCVIV: Crystal structure of hexacoordinate boron. Click for 3D<\/p><\/div>\n<div id=\"attachment_1107\" style=\"width: 327px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1107\" class=\"size-full wp-image-1107\" title=\"C5-BBr-aim\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/C5-BBr-aim.jpg\" alt=\"AIM analysis for  YOCVIV\" width=\"317\" height=\"278\" \/><p id=\"caption-attachment-1107\" class=\"wp-caption-text\">AIM analysis for  YOCVIV<\/p><\/div>\n<p>The  AIM analysis shows five bond critical points in the B-C regions and one in the  B-Br region. with \u03c1(r) values of 0.121 and 0.146 respectively. The corresponding \u2207<sup>2<\/sup>\u03c1 values were -0.07 and -0.22. These BCPs are matched by equally well defined disynaptic basins in the ELF analysis  with electron populations of respectively 0.67 and 2.1 electrons. This compares with \u03c1(r) values of 0.157 and 0.069, and ELF integrations of 1.22 and 2.0 calculated for the structurally similar\u00a0<a href=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=984\" target=\"_blank\">proposed<\/a> B-He compound.<\/p>\n<div id=\"attachment_1111\" style=\"width: 307px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1111\" class=\"size-full wp-image-1111\" title=\"C5-BBr-elf\" onclick=\"jmolInitialize('..\/Jmol\/');jmolSetAppletColor('yellow');jmolApplet([450,450],'load wp-content\/uploads\/2009\/10\/C5-BBr-elf.mol;zoom 120;spin 3;');\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/C5-BBr-elf.jpg\" alt=\"ELF analysis for YOCVIV\" width=\"297\" height=\"250\" \/><p id=\"caption-attachment-1111\" class=\"wp-caption-text\">ELF analysis for  YOCVIV. Click for 3D<\/p><\/div>\n<p>The analogy is sufficiently similar to suggest that (in this case boron) hypervalency for such first row main group elements can be reflected in real systems.<\/p>\n<!-- kcite active, but no citations found -->\n<\/div> <!-- kcite-section 1103 -->","protected":false},"excerpt":{"rendered":"<p>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 atom beyond eight, but in [&hellip;]<\/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":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[7],"tags":[2649,148,13],"ppma_author":[2661],"class_list":["post-1103","post","type-post","status-publish","format-standard","hentry","category-hypervalency","tag-hypervalency","tag-rare-gas-helium","tag-yocviv"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Hypervalency: a reality check - Henry Rzepa&#039;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=1103\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Hypervalency: a reality check - Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"og:description\" content=\"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 atom beyond eight, but in [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1103\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"article:published_time\" content=\"2009-10-05T19:26:26+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2009-10-05T20:01:04+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/BBr.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=\"1 minute\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Hypervalency: a reality check - Henry Rzepa&#039;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=1103","og_locale":"en_GB","og_type":"article","og_title":"Hypervalency: a reality check - Henry Rzepa&#039;s Blog","og_description":"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. 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Thus my third attempt, like a dog worrying a bone, to explore hypervalency. I have, somewhat to my\u2026","rel":"","context":"In &quot;Hypervalency&quot;","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\/2010\/10\/I8.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2599,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2599","url_meta":{"origin":1103,"position":1},"title":"Hypervalency: Is it real?","author":"Henry Rzepa","date":"October 16, 2010","format":false,"excerpt":"The Wikipedia page on hypervalent compounds reveals that the concept is almost as old as that of normally valent compounds. The definition there, \u00a0is \"a molecule that contains one or more\u00a0main group elements formally bearing more than eight\u00a0electrons in their\u00a0valence shells\" (although it could equally apply to e.g. transition elements\u2026","rel":"","context":"In &quot;Hypervalency&quot;","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\/2010\/10\/IH7.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":984,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=984","url_meta":{"origin":1103,"position":2},"title":"Uncompressed Monovalent Helium","author":"Henry Rzepa","date":"October 3, 2009","format":false,"excerpt":"Quite a few threads have developed in this series of posts, and following each leads in rather different directions. In this previous post the comment was made that coordinating a carbon dication to the face of a cyclopentadienyl anion resulted in a monocation which had a remarkably high proton affinity.\u2026","rel":"","context":"In &quot;Hypervalency&quot;","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"Inventing the  Helium bond","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/10\/C4-He.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2619,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2619","url_meta":{"origin":1103,"position":3},"title":"Hypervalency: I(CN)7 is not hypervalent!","author":"Henry Rzepa","date":"October 17, 2010","format":false,"excerpt":"In the last post, IH7 was examined to see if it might exhibit true hypervalency. The iodine, despite its high coordination, turned out not to be hypervalent, with its (s\/p) valence shell not exceeding eight electrons (and its d-shell still with 10, and the 6s\/6p shells largely unoccupied). Instead, the\u2026","rel":"","context":"In &quot;Hypervalency&quot;","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\/2010\/10\/ICN7.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":1103,"position":4},"title":"Hypervalent  Helium &#8211; 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 &quot;Hypervalency&quot;","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":19279,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=19279","url_meta":{"origin":1103,"position":5},"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 &quot;Hypervalency&quot;","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"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\/1103","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=1103"}],"version-history":[{"count":0,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1103\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1103"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1103"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1103"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=1103"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}