{"id":10870,"date":"2013-07-11T11:41:49","date_gmt":"2013-07-11T10:41:49","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=10870"},"modified":"2013-07-12T09:58:44","modified_gmt":"2013-07-12T08:58:44","slug":"the-butterfly-effect-in-chemistry-aromaticity-on-the-edge-of-chaos","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10870","title":{"rendered":"The butterfly effect in chemistry: aromaticity on the edge of chaos."},"content":{"rendered":"
\n

The butterfly effect<\/a>\u00a0summarises how a small change to a system may result in very large and often unpredictable (chaotic) consequences. If the system is merely on the edge of chaos, the consequences are predictable, but nevertheless finely poised between e.g.<\/em> two possible outcomes. Here I ask how a molecule might manifest such behaviour.<\/p>\n

\"chaos\"<\/p>\n

Two examples of the molecule above are known, differing only in the nature of the R group.<\/p>\n\n\n\n
\n
\"Click

CUWWEW. Click for 3D.<\/p><\/div>\n<\/td>\n

\n
\"Click

CUWWIA. Click for 3D.<\/p><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

CUWWEW is strongly buckled and shows no sign of cyclic conjugation, with the double bonds localised. On the other hand the very similar CUWWIA is essentially planar, being so because it contains ten \u03c0-electrons in a planar ring and so is 4n+2 aromatic (n=2) and becomes delocalised. However, neither form is entirely happy; CUWWEW relieves ring string (in a flat 8-ring the internal angles are ~140\u00b0, a significant departure from that preferred for sp2<\/sup> hydridisation) but looses any stabilisation from aromaticity. For CUWWIA the reverse is true.<\/p>\n

Clearly these two effects are finely balanced for this system and the result is a pair of molecules on the edge of chaos, where a small change to the R group can tip the molecule over from one state to another.[1]<\/a><\/span>,[2]<\/a><\/span> I may return to this particular theme in future posts, whereby two molecules which differ perhaps only in substituents, nevertheless adopt quite different geometries and properties.<\/p>\n

References<\/h2>\n
  1. H.S. Rzepa, and N. Sanderson, \"Aromaticity on the edge of chaos: An ab initio study of the bimodal balance between aromatic and non-aromatic structures for 10\u03c0-dihetero[8]annulenes\", Phys. Chem. Chem. Phys.<\/i>, vol. 6, pp. 310-313, 2004. https:\/\/doi.org\/10.1039\/b312724a<\/a>\n\n<\/li>\n
  2. H.S. Rzepa *, and N. Sanderson, \"Aromaticity on the edge of chaos: an<i>Ab initio<\/i>CCSD(T) study of the bimodal balance between aromatic and non-aromatic structures for 10-\u03c0-diheterocins and heteronins\", Molecular Physics<\/i>, vol. 103, pp. 401-405, 2005. https:\/\/doi.org\/10.1080\/00268970512331317796<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    The butterfly effect\u00a0summarises how a small change to a system may result in very large and often unpredictable (chaotic) consequences. If the system is merely on the edge of chaos, the consequences are predictable, but nevertheless finely poised between e.g. two possible outcomes. Here I ask how a molecule might manifest such behaviour. Two examples […]<\/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,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","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":[4],"tags":[],"ppma_author":[2661],"class_list":["post-10870","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\nThe butterfly effect in chemistry: aromaticity on the edge of chaos. - Henry Rzepa's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10870\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The butterfly effect in chemistry: aromaticity on the edge of chaos. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"The butterfly effect\u00a0summarises how a small change to a system may result in very large and often unpredictable (chaotic) consequences. If the system is merely on the edge of chaos, the consequences are predictable, but nevertheless finely poised between e.g. two possible outcomes. Here I ask how a molecule might manifest such behaviour. Two examples […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10870\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2013-07-11T10:41:49+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2013-07-12T08:58:44+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/07\/chaos.svg\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"The butterfly effect in chemistry: aromaticity on the edge of chaos. - Henry Rzepa's Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10870","og_locale":"en_GB","og_type":"article","og_title":"The butterfly effect in chemistry: aromaticity on the edge of chaos. - Henry Rzepa's Blog","og_description":"The butterfly effect\u00a0summarises how a small change to a system may result in very large and often unpredictable (chaotic) consequences. If the system is merely on the edge of chaos, the consequences are predictable, but nevertheless finely poised between e.g. two possible outcomes. Here I ask how a molecule might manifest such behaviour. 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It represents a class of Mo-complex ligated by two dithiocarbamate ligands and two aryl nitrene ligands (Ar-N:). I focus on two specific examples, where R=R'\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"Click for c3D","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/07\/PNTCMO.jpeg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2084,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2084","url_meta":{"origin":10870,"position":1},"title":"Chemistry with a super-twist: A molecular trefoil knot, part 2.","author":"Henry Rzepa","date":"June 1, 2010","format":false,"excerpt":"A conjugated, (apparently) aromatic molecular trefoil might be expected to have some unusual, if not extreme properties. Here some of these are explored. The first is the vibrational spectrum. With 144 atoms for this molecule, it has 426 vibrational modes, but one is highlighted below. This is the mode that\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2010\/06\/trefoil-kekule.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":17771,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17771","url_meta":{"origin":10870,"position":2},"title":"Reaction coordinates vs Dynamic trajectories as illustrated by an example reaction mechanism.","author":"Henry Rzepa","date":"March 20, 2017","format":false,"excerpt":"The example a few posts back of how methane might invert its configuration by transposing two hydrogen atoms illustrated the reaction mechanism by locating a transition state and following it down in energy using an intrinsic reaction coordinate\u00a0(IRC). Here I explore an alternative method based instead on computing a molecular\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":63,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=63","url_meta":{"origin":10870,"position":3},"title":"The SN-1 Reaction live!","author":"Henry Rzepa","date":"April 3, 2009","format":false,"excerpt":"The ionization of a C-X bond (X=halogen) to form what we call a carbocation and which is known as the SN-1 reaction goes way back in the history of chemistry. Julius Steglitz was probably the first person to suggest such an ionization, back in 1899 (Steglitz, J.; Am. Chem. J.,\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"SN-1 Reaction. Click on image to see 3D model","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/sn1.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2046,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2046","url_meta":{"origin":10870,"position":4},"title":"Chemistry with a super-twist: A molecular trefoil knot, part 1.","author":"Henry Rzepa","date":"May 31, 2010","format":false,"excerpt":"Something important happened in chemistry for the first time about 100 years ago. A molecule was built (nowadays we would say synthesized) specifically for the purpose of investigating a theory. It was cyclo-octatetraene or (CH)8, and it was made by Willst\u00e4tter and Waser to try to find out if benzene,\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2010\/05\/metallatrefoil.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":1937,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1937","url_meta":{"origin":10870,"position":5},"title":"Semantically rich molecules","author":"Henry Rzepa","date":"May 2, 2010","format":false,"excerpt":"Peter Murray-Rust in his blog asks for examples of the Scientific Semantic Web, a topic we have both been banging on about for ten years or more (DOI: 10.1021\/ci000406v). What we are seeking of course is an example of how scientific connections have been made using inference logic from semantically\u2026","rel":"","context":"In "Chemical IT"","block_context":{"text":"Chemical IT","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2010\/05\/DULSAE.jpg?resize=350%2C200","width":350,"height":200},"classes":[]}],"jetpack_likes_enabled":false,"authors":[{"term_id":2661,"user_id":1,"is_guest":0,"slug":"admin","display_name":"Henry Rzepa","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/10870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10870"}],"version-history":[{"count":7,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/10870\/revisions"}],"predecessor-version":[{"id":10882,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/10870\/revisions\/10882"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10870"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10870"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10870"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=10870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}