{"id":50,"date":"2015-03-30T17:45:35","date_gmt":"2015-03-30T17:45:35","guid":{"rendered":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/?page_id=50"},"modified":"2015-04-02T09:00:20","modified_gmt":"2015-04-02T09:00:20","slug":"chemical-structure-and-change","status":"publish","type":"page","link":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/chemical-structure-and-change\/","title":{"rendered":"Chemical Structure and Change"},"content":{"rendered":"

Structural Distortion in Hydrocarbons on Coordination\u00a0to Copper and Silver Chloride<\/strong><\/p>\n

Copper, silver and gold are\u00a0used industrially\u00a0as catalysts for\u00a0the hydrogenation of ethyne into\u00a0ethene. Our experiments have recently probed how the geometry of ethyne\u00a0changes on\u00a0attachment to CuCl and AgCl. Our experiments show that the bond length separating the carbon atoms within ethyne increases and this\u00a0is\u00a0accompanied by a\u00a0significant\u00a0change in the CCH angle (see molecular geometry below) with respect to the linear geometry of isolated ethyne. On\u00a0attaching to AgCl, the CCH angle increases by 8 degrees and when attaching to CuCl, it\u00a0increases by\u00a012 degrees. Beyond\u00a0precisely\u00a0quantifying the\u00a0structural rearrangements occurring in these complexes, these experiments provide insight into the chemical re-arrangement that accompanies the adsorption of hydrocarbons onto\u00a0metal catalyst surfaces.<\/p>\n

\"C2H2-CuCl\"<\/a>\"C6H6-AgCl<\/p>\n

Left: \u00a0Geometry of C2<\/sub>H2<\/sub>-CuCl \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0Right: Geometry of C6<\/sub>H6<\/sub>-AgCl<\/p>\n

Halogen Bonding in\u00a0Trifluoroiodomethane Complexes<\/strong><\/p>\n

Networks of halogen bonds between perfluoroiodoalkane building blocks have been shown to enhance the structural stability of novel crystalline substances characterised in the condensed phase. The resulting materials have promising applications and properties determined by the strength and nature of their contained halogen bonds. Trifluoroiodomethane is the simplest example of a perfluoroiodoalkane.<\/p>\n

We have examined the geometry and stiffness (as represented by the force constant) of the intermolecular bond formed between CF3<\/sub>I and a range of small molecules. Amongst the strongest interactions of those examined are the interactions with ammonia (NH3<\/sub>) and trimethylamine (N(CH3<\/sub>)3<\/sub>). Like ammonia, trimethylamine has C3v<\/sub> symmetry and coordinates to CF3<\/sub>I via a halogen bond formed between the nitrogen and iodine atoms. However, trimethylamine forms a bond that is somewhat shorter and stiffer than that existing between NH3<\/sub> and CF3<\/sub>I. Trimethylamine is geometrically similar to\u00a0NH3<\/sub>– the basic C3v<\/sub> geometry of NH3<\/sub> is also present in\u00a0(N(CH3<\/sub>)3<\/sub>) but the hydrogen atoms are replaced by\u00a0CH3<\/sub> groups. The electron-donating properties of these methyl groups give trimethylamine slightly higher nucleophilicity than NH3<\/sub>, leading to the stronger interaction.<\/p>\n

\"Figure5\"<\/a><\/p>\n

Above: The geometry of CF3<\/sub>I-NH3<\/sub><\/p>\n

Link to other publications<\/a><\/p>\n

1.\u00a0Changes in the Geometries of C2<\/sub>H2<\/sub> and C2<\/sub>H4<\/sub> on Coordination to CuCl\u00a0Revealed by Broadband Rotational Spectroscopy and ab-Initio\u00a0Calculations<\/em>, S.L. Stephens, D.M. Bittner, V.A. Mikhailov, W. Mizukami, D.P. Tew, N.R. Walker and A.C. Legon., Inorg. Chem.<\/em> 53<\/strong>, 10722 (2014)
\n2.\u00a0Distortion of ethyne on formation of a \u03c0 complex with silver chloride: C2<\/sub>H2<\/sub>-Ag\u2013Cl characterised by rotational spectroscopy and ab initio calculations<\/em>, S.L. Stephens, W. Mizukami, D.P. Tew, N.R. Walker and A.C. Legon., J. Chem. Phys.<\/em> 137<\/strong>, 174302 (2012).<\/p>\n","protected":false},"excerpt":{"rendered":"

Structural Distortion in Hydrocarbons on Coordination\u00a0to Copper and Silver Chloride Copper, silver and gold are\u00a0used industrially\u00a0as catalysts for\u00a0the hydrogenation of ethyne into\u00a0ethene. Our experiments have recently probed how the geometry of ethyne\u00a0changes on\u00a0attachment to CuCl and AgCl. Our experiments show … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1061,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-50","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/pages\/50","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/users\/1061"}],"replies":[{"embeddable":true,"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/comments?post=50"}],"version-history":[{"count":86,"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/pages\/50\/revisions"}],"predecessor-version":[{"id":314,"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/pages\/50\/revisions\/314"}],"wp:attachment":[{"href":"https:\/\/www.staff.ncl.ac.uk\/nick.walker\/wp-json\/wp\/v2\/media?parent=50"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}