{"id":3977,"date":"2011-04-29T07:26:20","date_gmt":"2011-04-29T07:26:20","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=3977"},"modified":"2011-04-29T07:26:20","modified_gmt":"2011-04-29T07:26:20","slug":"nobelocene-a-hypothetical-32-electron-shell-molecule","status":"publish","type":"post","link":"https:\/\/www.rzepa.net\/blog\/?p=3977","title":{"rendered":"Nobelocene: a (hypothetical) 32-electron shell molecule?"},"content":{"rendered":"
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The two previous posts<\/a> have explored one of the oldest bonding rules (pre-dating quantum mechanics), which postulated that filled valence shells in atoms forming molecules follow the magic numbers 2, 8, 18 and 32. Of the 59,025,533 molecules documented at the instant I write this post, only one example<\/a> is claimed for the 32-electron class. Here I suggest another, Nobelocene<\/strong> (one which given the radioactive instability of nobelium, is unlikely to be ever confirmed experimentally!)<\/p>\n

Nobelium has the electronic configuration [Rn].5f14<\/sup>.7s2 <\/sup>, which means the 6d and\u00a07p shells are still empty. Filling these would take 10+6 electrons, or four more\u00a0electrons (20<\/strong>) if one starts from No4+<\/sup>, resulting in a complete 32-electron filled shell for the Nobelium. These twenty electrons could be provided by two cyclo-octatetraenyl (COT) dianion ligands. Nobelium, with its nuclear charge of +102, has highly relativistic inner-shell electrons, and so special techniques must be used to model this. Here I have used a SARC all electron relativistically contracted<\/em> basis set (DOI:\u00a010.1021\/ct100736b<\/a>), to be used with the\u00a0Douglas\u2212Kroll\u2212Hess scalar relativistic Hamiltonian (<\/em>for details, see here<\/a>). The QTAIM analysis is shown below (quite a spider’s web):<\/p>\n

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Nobelocene. AIM analysis. Click for 3D.<\/p><\/div>There are 16 bond critical points located along the lines of each No..C, with \u03c1(r) 0.03. This is a very low value indeed for a covalent bond, being of the same order as strong hydrogen bonds, and so should be classed as an interaction rather than a bond. ELF basins cannot normally be located for hydrogen bonds, and neither can they here. Nobelocene in this regard is pretty boring, being almost entirely ionic.<\/p>\n

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ELF analysis for Nobelocene.<\/p><\/div>Rather more interesting are the molecular orbitals. The most stable \u03c0-type is shown below. Many of the orbitals show the Nobelium atomic orbitals non-interacting with the ligand, probably because the relativistic contraction renders them inert to mixing, in a manner which is often used to explain the inert nature of e.g. the Pb 6s2<\/sup> electrons in divalent lead.<\/p>\n

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Molecular orbital for nobelocene. Click for 3D.<\/p><\/div>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

The two previous posts have explored one of the oldest bonding rules (pre-dating quantum mechanics), which postulated that filled valence shells in atoms forming molecules follow the magic numbers 2, 8, 18 and 32. Of the 59,025,533 molecules documented at the instant I write this post, only one example is claimed for the 32-electron class. […]<\/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,"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":[6],"tags":[525,287],"class_list":["post-3977","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-hess","tag-pence"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1gPyz-129","jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3977","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3977"}],"version-history":[{"count":0,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3977\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3977"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3977"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3977"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}