{"id":4413,"date":"2011-06-12T15:12:07","date_gmt":"2011-06-12T15:12:07","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=4413"},"modified":"2011-06-12T15:12:07","modified_gmt":"2011-06-12T15:12:07","slug":"buses-and-dyotropic-rearrangements-always-come-in-threes","status":"publish","type":"post","link":"https:\/\/www.rzepa.net\/blog\/?p=4413","title":{"rendered":"Buses (and dyotropic rearrangements) always come in threes."},"content":{"rendered":"
\n

The last two posts have played a game of find the electrons. We saw how the dyotropic rearrangement of ethane<\/a> borrowed electrons from the C-C bond, and how\u00a01,2,dibromoethane<\/a> went ionic on us. How about this mixed system, in which a hydrogen and a BH2<\/sub> swap their positions?<\/p>\n

\"\"<\/a>

Dyotropic rearrangement involving boron and hydrogen.<\/p><\/div>\n

It is yet again different. Unlike the ethane system, this C2v<\/sub>-symmetric system is a true transition state, with no other distorsions. The C-C distance is an unusual 1.729\u00c5, whilst the C-B distances are a more normal 1.61\u00c5.<\/p>\n\n\n\n
\"\"

Transition state for H\/BH2 transposition. Click for 3D.<\/p><\/div><\/td>\n

\n

\"\"<\/a>

Intrinsic reaction coordinate for the dyotropic rearrangement.<\/p><\/div><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The ELF partitioning shows 1.81 electrons in C-B disynaptic basins (red, below), and 1.91 electrons in a trisynaptic\u00a0C-H-C basin (yellow, below), or 5.53 in total. No discrete C-C basin is found, and no evidence either of ionicity as with dibromoethane.<\/p>\n

\"\"<\/a>

ELF analysis.<\/p><\/div>\n

Finally, adding two electrons into the system, as with NH2<\/sub> replacing BH2<\/sub>, produces a similar result but now with the\u00a0C…C region populated with 2.22 electrons (the surprise is that this extra electron pair is NOT associated with the nitrogen). These extra electrons reduces the\u00a0C-C bond length to 1.395\u00c5.<\/p>\n

\"\"<\/a>

ELF analysis for NH2\/H transposition.<\/p><\/div>\n

What an adventure. It reminds us never to take for granted where the electrons are in a molecule (or the transition states for its reactions), although to be fair we can normally guess pretty well.<\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

The last two posts have played a game of find the electrons. We saw how the dyotropic rearrangement of ethane borrowed electrons from the C-C bond, and how\u00a01,2,dibromoethane went ionic on us. How about this mixed system, in which a hydrogen and a BH2 swap their positions? It is yet again different. Unlike the ethane […]<\/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":[1],"tags":[562,1529,1527],"class_list":["post-4413","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-dyotropic","tag-pericyclic","tag-tutorial-material"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1gPyz-19b","jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4413","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=4413"}],"version-history":[{"count":0,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4413\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4413"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}