{"id":2207,"date":"2010-07-11T09:31:57","date_gmt":"2010-07-11T08:31:57","guid":{"rendered":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2207"},"modified":"2010-07-11T09:31:57","modified_gmt":"2010-07-11T08:31:57","slug":"tunable-bonds-looked-at-in-a-different-way","status":"publish","type":"post","link":"https:\/\/rzepa.net\/blog\/2010\/07\/11\/tunable-bonds-looked-at-in-a-different-way\/","title":{"rendered":"Tunable bonds looked at in a different way"},"content":{"rendered":"

The title of this post merges those of the two previous<\/a> ones. The tunable C-Cl bond brought about in the molecule tris(amino)chloromethane by anomeric effects will be probed using the Laplacian of the electronic density<\/a>.<\/p>\n

\"\"
Laplacian @0.67 for tris(amino)choromethane. Click for 3D<\/figcaption><\/figure>\n

The figure above shows the Laplacian for a conformation of tris(amino)chloromethane with one of the nitrogen lone pairs antiperiplanar to the C-Cl bond, and the other two lone pairs antiperiplanar to C-N bonds. The features visible at an isosurface of \u00b1 0.67 include<\/p>\n

    \n
  1. (a) The Laplacian here has a value of -0.67 (= red isosurface), which indicates an accumulation of (covalent) shared density along the C-N bond (underneath this surface, you can see the blue sphere representing depletions from the nitrogen atomic region). This bond has the lone pair antiperiplanar to a C-N bond.<\/li>\n
  2. (b) Contrast this with the C-N bond which is antiperiplanar to the C-Cl bond. A greater volume of the covalent C-N region is bounded by this isosurface. More of the N lone pair on this atom is donating into the C-N, as more conventionally represented below.<\/li>\n
  3. Notice how the red isosurface associated with the N lone pair and the region associated with the C-N bond are in fact contiguous, and not separated basins!\n

    \"\"<\/a>
    Anomeric donation<\/figcaption><\/figure><\/li>\n
  4. (c) represents the lone pairs on the chlorine, which have been augmented by the donation from the nitrogen. Notice how they come out as a torus rather than the conventional double dot representations!<\/li>\n
  5. Notice the absence of any features along the C-Cl bond! This would be typical of a fully or even partially ionic bond, but it also illustrates that with a property such as the Laplacian, one does not get a complete picture by inspecting at just one isosurface value.<\/li>\n<\/ol>\n

    The next isosurface chosen is 0.3. At this lower value, more depletions (blue = electrophilic regions) are seen and a tiny feature now appears along the C-Cl bond, which is the covalent accumulation of that bond, a feature that grows @ 0.2. This nicely illustrates the variable covalency\/ionicity of the C-Cl bond. Notice also how the lhs is all red (anionic) and the rhs is mostly blue (cationic), showing the formation of in effect an ion pair.<\/p>\n\n\n\n
    \n

    \"\"
    tris(amino)chloroethane @ 0.3<\/figcaption><\/figure><\/td>\n
    		\n

    \"\"
    tris(amino)chloroethane @ 0.2<\/figcaption><\/figure><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    There are many other features which can be explored in these Laplacian maps, but I leave those for the reader to indulge in. Just click on any of the diagrams above,and start your exploration.<\/p>\n","protected":false},"excerpt":{"rendered":"

    The title of this post merges those of the two previous ones. The tunable C-Cl bond brought about in the molecule tris(amino)chloromethane by anomeric effects will be probed using the Laplacian of the electronic density. The figure above shows the Laplacian for a conformation of tris(amino)chloromethane with one of the nitrogen lone pairs antiperiplanar to […]<\/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":[170,445,1290,1421],"class_list":["post-2207","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-anomeric-effect","tag-chemical-energy","tag-interesting-chemistry","tag-laplacian"],"_links":{"self":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/posts\/2207","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=2207"}],"version-history":[{"count":0,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/posts\/2207\/revisions"}],"wp:attachment":[{"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/media?parent=2207"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/categories?post=2207"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rzepa.net\/blog\/wp-json\/wp\/v2\/tags?post=2207"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}