{"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:\/\/rzepa.net\/blog\/2011\/04\/29\/nobelocene-a-hypothetical-32-electron-shell-molecule\/","title":{"rendered":"Nobelocene: a (hypothetical) 32-electron shell molecule?"},"content":{"rendered":"<p>The <a href=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=3956\" target=\"_blank\">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 <a href=\"http:\/\/dx.doi.org\/10.1002\/anie.200604198\" target=\"_blank\">one example<\/a> is claimed for the 32-electron class. Here I suggest another, <strong>Nobelocene<\/strong> (one which given the radioactive instability of nobelium, is unlikely to be ever confirmed experimentally!)<\/p>\n<p>Nobelium has the electronic configuration [Rn].5f<sup>14<\/sup>.7s<sup>2 <\/sup>, which means the 6d and\u00a07p shells are still empty. Filling these would take 10+6 electrons, or four more\u00a0electrons (<strong>20<\/strong>) if one starts from No<sup>4+<\/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 a<em>ll electron relativistically contracted<\/em> basis set (DOI:\u00a0<a href=\"http:\/\/dx.doi.org\/10.1021\/ct100736b\" target=\"_blank\">10.1021\/ct100736b<\/a>), to be used with the\u00a0<em>Douglas\u2212Kroll\u2212Hess scalar relativistic Hamiltonian (<\/em>for details, <a href=\"http:\/\/hdl.handle.net\/10042\/to-8401\" target=\"_blank\">see here<\/a>). The QTAIM analysis is shown below (quite a spider&#8217;s web):<\/p>\n<p><figure id=\"attachment_3979\" aria-describedby=\"caption-attachment-3979\" style=\"width: 220px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-3979\" title=\"nobelocene_aim\" onclick=\"jmolInitialize('..\/Jmol\/');jmolSetAppletColor('white');jmolApplet([450,450],'load wp-content\/uploads\/2011\/04\/No-aim.mol2;spin 3;');\" src=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/04\/nobelocene_aim.jpg\" alt=\"\" width=\"220\" height=\"216\" \/><figcaption id=\"caption-attachment-3979\" class=\"wp-caption-text\">Nobelocene. AIM analysis. Click for 3D.<\/figcaption><\/figure>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<p><figure id=\"attachment_3981\" aria-describedby=\"caption-attachment-3981\" style=\"width: 318px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-3981\" title=\"nobelocene_elf\" onclick=\"jmolInitialize('..\/Jmol\/');jmolSetAppletColor('white');jmolApplet([450,450],'load wp-content\/uploads\/2011\/04\/Nob_bas.mol2;spin 3;');\" src=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/04\/nobelocene_elf.jpg\" alt=\"\" width=\"318\" height=\"308\" \/><figcaption id=\"caption-attachment-3981\" class=\"wp-caption-text\">ELF analysis for Nobelocene.<\/figcaption><\/figure>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 6s<sup>2<\/sup> electrons in divalent lead.<\/p>\n<figure id=\"attachment_3983\" aria-describedby=\"caption-attachment-3983\" style=\"width: 159px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-3983\" title=\"nobelocene_mo84\" onclick=\"jmolInitialize('..\/Jmol\/');jmolSetAppletColor('white');jmolApplet([450,450],'load wp-content\/uploads\/2011\/04\/No_mo84_0.02.jvxl;isosurface &quot;&quot; translucent;zoom 100;spin 3;');\" src=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/04\/nobelocene_mo84.jpg\" alt=\"\" width=\"159\" height=\"136\" \/><figcaption id=\"caption-attachment-3983\" class=\"wp-caption-text\">Molecular orbital for nobelocene. Click for 3D.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>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. [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[1167,1879],"class_list":["post-3977","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-hess","tag-pence"],"_links":{"self":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/posts\/3977","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/comments?post=3977"}],"version-history":[{"count":0,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/posts\/3977\/revisions"}],"wp:attachment":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/media?parent=3977"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/categories?post=3977"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/tags?post=3977"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}