{"id":16497,"date":"2016-06-10T08:26:13","date_gmt":"2016-06-10T07:26:13","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=16497"},"modified":"2016-06-10T08:26:13","modified_gmt":"2016-06-10T07:26:13","slug":"a-wider-look-at-chlorine-trifluoride-crystal-structures-and-data-mining","status":"publish","type":"post","link":"https:\/\/www.rzepa.net\/blog\/?p=16497","title":{"rendered":"A wider look at chlorine trifluoride: crystal structures and data mining."},"content":{"rendered":"
\n

\n\tA while ago, I explored<\/a> how the 3-coordinate halogen compound ClF3<\/sub> is conventionally analyzed using VSEPR (valence shell electron pair repulsion theory). Here I (belatedly) look at other such tri-coordinate halogen compounds using known structures gleaned from the crystal structure database (CSD).\n<\/p>\n

\n\t\"\"\n<\/p>\n

\n\tThe search query specifies 7A as the central atom, defined with just three bonded (non-metallic) atoms. Initially, if no constraint on any cyclicity in the three 7A-NM bonds is made (and with R < 0.1, no errors, no disorder), the following result emerges.\n<\/p>\n

\n\t\"\"\n<\/p>\n

\n\tI have plotted the three angle variables using the X\/Y axes above and used colour to indicate the third angle (red = ~180°, blue = ~90°). The clusters show that two of the angles are ~90° and only one is ~180°. There is also a set of blue points (~90°) which show a linear correlation and which can be shown to derive from cyclicity, as the plot below reveals when acyclicity is specified for all three NM-7A bonds.\n<\/p>\n

\n\t\"\"\n<\/p>\n

\n\tIn this distribution, the two clusters for ANG1 or ANG2 of ~180° are small and compact, but the cluster where both ANG1 and ANG2 are ~90° is much more diffuse. Not all of the points in this cluster show as red (ANG3 ~180°); there are a few cyan or blue examples here too; indicating all three angles are in the range 140-90°. This result is not arising from cyclic constraints. \n<\/p>\n

\n\tThis wider look at 3-coordinate compounds in group 17 (the halogens) quickly reveals a class of such molecules where all three angles are relatively small. This suggests that a closer look at the bonding in these systems, especially in terms of VSEPR, might be rewarding!\n<\/p>\n

\n\tI end with an equivalent search for group 18 (the noble gases). Although the number of examples is small, all show the two small\/one large angle so characteristic of chlorine trifluoride itself. \n<\/p>\n

\n\t\"\"\n<\/p>\n

\n\tThe above is I think a good example of (big?) data mining, where one is searching for patterns, and if lucky spotting patterns that deviate from the norm to investigate the possibility of new chemical phenomena.[1]<\/a><\/span> It is also interesting to speculate upon the origins of why two of the clusters shown above are small and compact and the third is much more diffuse.<\/p>\n

References<\/h2>\n
  1. H.S. Rzepa, \"Discovering More Chemical Concepts from 3D Chemical Information Searches of Crystal Structure Databases\", Journal of Chemical Education<\/i>, vol. 93, pp. 550-554, 2015. https:\/\/doi.org\/10.1021\/acs.jchemed.5b00346<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    A while ago, I explored how the 3-coordinate halogen compound ClF3 is conventionally analyzed using VSEPR (valence shell electron pair repulsion theory). Here I (belatedly) look at other such tri-coordinate halogen compounds using known structures gleaned from the crystal structure database (CSD). The search query specifies 7A as the central atom, defined with just three bonded (non-metallic) atoms. Initially, […]<\/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":[1754],"tags":[1566,1088,1787,1456,1830],"class_list":["post-16497","post","type-post","status-publish","format-standard","hentry","category-crystal_structure_mining","tag-chemical-phenomena","tag-data-mining","tag-equivalent-search","tag-halogen","tag-search-query-specifies-7a"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1gPyz-4i5","jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/16497","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=16497"}],"version-history":[{"count":0,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/16497\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16497"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16497"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16497"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}