{"id":17252,"date":"2016-12-21T07:52:19","date_gmt":"2016-12-21T07:52:19","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=17252"},"modified":"2016-12-23T07:51:58","modified_gmt":"2016-12-23T07:51:58","slug":"forking-the-most-polar-neutral-compound-synthesized-into-m-benzyne","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17252","title":{"rendered":"Forking “The most polar neutral compound synthesized” into m-benzyne."},"content":{"rendered":"
\n

A project fork<\/a> is defined (in computing) as creating a distinct and separate strand from an existing (coding) project. Here I apply the principle to the polar azulene 4<\/strong> explored in an earlier post<\/a>, taking m-benzyne as a lower homologue of azulene as my starting point.<\/p>\n

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

m-Benzyne<\/a> is a less\u00a0stable 1,3 isomer of o-benzyne (1,2-dehydrobenzene), and is often represented as a 1,3-biradical of 1,3-dehydrobenzene. But, could it be stabilized with cyano and amino groups as shown in 5<\/strong> above? Here the idea is that charge transfer from the 3-ring to the 5-ring will create a lower homologue of azulene (a well known molecule), with the 3-ring a 4n+2 \u03c0-electron aromatic (n=0) and the five ring similarly so\u00a0(n=1).<\/p>\n

I start with the computed (wB97XD\/Def2-TZVPP\/SCRF=thf) structure of m-benzyne itself, as a closed shell molecule (DOI:\u00a010.14469\/hpc\/1995<\/span><\/a>). The C-C bond connecting the two rings is long (with a biradical tendency) and hence the conjugation is restricted to the outer periphery. The dipole moment is 0.51D (the dipole vector as shown in blue has the expected direction of polarity).<\/p>\n

\"\"<\/p>\n

Now compare this to the substituted version 5;<\/strong>\u00a0the bond lengths are all more characteristic of aromatic values and most significantly the central bond is as well (DOI:\u00a010.14469\/hpc\/1996<\/span><\/a>). The dipole moment is augmented thirty fold to 14.6D<\/span><\/strong>, which would rank alongside that reported for the most polar neutral molecule.<\/p>\n

\"\"<\/p>\n

So I suggest this is substituted “m-benzyne” well worth trying to make and one very much unlikely to have any dispute about the nature of its wavefunction, i.e.<\/em> biradical or closed shell.<\/p>\n

\n
\n
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1<\/div>\n
Henry Rzepa, 2016. [Source<\/a>]<\/span><\/div>\n<\/div>\n<\/div>\n
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2<\/div>\n
Henry Rzepa, 2016. [Source<\/a>]<\/span><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

A project fork is defined (in computing) as creating a distinct and separate strand from an existing (coding) project. Here I apply the principle to the polar azulene 4 explored in an earlier post, taking m-benzyne as a lower homologue of azulene as my starting point. m-Benzyne is a less\u00a0stable 1,3 isomer of o-benzyne (1,2-dehydrobenzene), […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_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},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[1955,1956,1957,1395,1463,1958],"ppma_author":[2661],"class_list":["post-17252","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-aryne","tag-azulene","tag-chemical-polarity","tag-chemistry","tag-dipole","tag-extreme-umpolung"],"yoast_head":"\nForking "The most polar neutral compound synthesized" into m-benzyne. - 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=17252\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Forking "The most polar neutral compound synthesized" into m-benzyne. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"A project fork is defined (in computing) as creating a distinct and separate strand from an existing (coding) project. Here I apply the principle to the polar azulene 4 explored in an earlier post, taking m-benzyne as a lower homologue of azulene as my starting point. m-Benzyne is a less\u00a0stable 1,3 isomer of o-benzyne (1,2-dehydrobenzene), […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17252\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2016-12-21T07:52:19+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2016-12-23T07:51:58+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2016\/12\/polar-fork.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":"Forking \"The most polar neutral compound synthesized\" into m-benzyne. - 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=17252","og_locale":"en_GB","og_type":"article","og_title":"Forking \"The most polar neutral compound synthesized\" into m-benzyne. - Henry Rzepa's Blog","og_description":"A project fork is defined (in computing) as creating a distinct and separate strand from an existing (coding) project. 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Inspired by the report of the most polar neutral compound yet made, I suggested some candidates based on the azulene ring system that if made might be even more polar. This then led to considering a smaller \u03c0-analogue of azulene, m-benzyne. Here I ponder how a\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\/2017\/01\/polar-Cla.gif?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3003,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=3003","url_meta":{"origin":17252,"position":1},"title":"Janus mechanisms (the past and the future): Reactions of the diazonium cation.","author":"Henry Rzepa","date":"December 11, 2010","format":false,"excerpt":"Janus was the mythological Roman god depicted as having two heads facing opposite directions, looking simultaneously into the past and the future. Some of the most ancient (i.e. 19th century) known reactions can be considered part of a chemical mythology; perhaps it is time for\u00a0a Janus-like look into their future.\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\/12\/diazonium.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":17205,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17205","url_meta":{"origin":17252,"position":2},"title":"Molecules of the year? The most polar neutral compound synthesized…","author":"Henry Rzepa","date":"December 18, 2016","format":false,"excerpt":"This, the fourth candidate provided by C&EN for a vote for the molecule of the year\u00a0as discussed here,\u00a0lays claim to the World's most polar neutral molecule (system 1 shown below). Here I explore\u00a0a strategy for extending that record. The claim for 1 (3 in\u00a0) is on the basis of its\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":"","width":0,"height":0},"classes":[]},{"id":2828,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2828","url_meta":{"origin":17252,"position":3},"title":"Can a cyclobutadiene and carbon dioxide co-exist in a calixarene cavity?","author":"Henry Rzepa","date":"November 19, 2010","format":false,"excerpt":"On 8th August this year, I posted on a fascinating article that had just appeared in Science in which the crystal structure was reported of two small molecules,\u00a01,3-dimethyl cyclobutadiene\u00a0and\u00a0carbon dioxide, entrapped together inside a calixarene cavity. Other journals (e.g.\u00a0Nature Chemistry ran the article as a research highlight (where the purpose\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\/11\/cbd.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2355,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2355","url_meta":{"origin":17252,"position":4},"title":"Reactions in supramolecular cavities – trapping a cyclobutadiene: ! or ?","author":"Henry Rzepa","date":"August 8, 2010","format":false,"excerpt":"Cavities promote reactions, and they can also trap the products of reactions. Such (supramolecular) chemistry is used to provide models for how enzymes work, but it also allows un-natural reactions to be undertaken. A famous example is the preparation of P4 (see blog post here), an otherwise highly reactive species\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\/08\/scheme.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":9894,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=9894","url_meta":{"origin":17252,"position":5},"title":"To be cyclobutadiene, or not to be, that is the question? You decide.","author":"Henry Rzepa","date":"March 21, 2013","format":false,"excerpt":"A quartet of articles has recently appeared on the topic of cyclobutadiene.,,,. You will find a great deal discussed there, but I can boil it down to this essence. Do the following coordinates (obtained from a (disordered) previously published x-ray refinement) correspond to a van der Waals complex of 1,3-dimethyl\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":"","width":0,"height":0},"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","author_category":"1","first_name":"Henry","last_name":"Rzepa","user_url":"https:\/\/orcid.org\/0000-0002-8635-8390","job_title":"","description":"Henry Rzepa is Emeritus Professor of Computational Chemistry at Imperial College London."}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/17252","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=17252"}],"version-history":[{"count":18,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/17252\/revisions"}],"predecessor-version":[{"id":17278,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/17252\/revisions\/17278"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17252"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17252"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=17252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}