{"id":24027,"date":"2021-07-11T09:54:36","date_gmt":"2021-07-11T08:54:36","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=24027"},"modified":"2021-07-21T14:29:16","modified_gmt":"2021-07-21T13:29:16","slug":"molecules-with-very-large-dipole-moments-cyclopropenium-acetylide","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027","title":{"rendered":"Molecules with very large dipole moments: cyclopropenium acetylide"},"content":{"rendered":"
\n

Occasionally, someone comments about an old post here, asking a question. Such was the case here<\/a>, when a question about the dipole moment of cyclopropenylidene arose. It turned out to be 3.5D, but this question sparked a thought about the related molecule below.<\/p>\n

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

Of the two resonance forms show above, the one on the left is a zwitterion resulting in the formation of an aromatic cyclopropenium ring, with the charge balanced by the acetylide anion.‡<\/sup> The calculated structure (\u03c9B97XD\/Def2-TZVPP\/SCRF=chloroform, Data DOI 10.14469\/hpc\/8399<\/a> ) shows a short terminal CC bond which indicates a significant degree of delocalisation of the three membered ring.<\/p>\n

\"\"

Molecular electrostatic potential<\/p><\/div>\n

The molecular electrostatic potential (above) agrees with a large dipole moment of 11.9D. This is certainly up there with the molecule suggested in 2016 as being the most polar molecule neutral compound synthesised[1]<\/a><\/span> and is a fair bit smaller than that candidate. A brief search of the literature (Scifinder) suggest that the molecule is currently unknown. Anybody fancy making it?<\/p>\n

The Data DOI by the way gives you access to the other outputs from the calculation, which would include the molecular orbitals and the molecular vibrations which I have not shown here.<\/p>\n

\n

‡<\/sup> Such zwitterions are known as unstable intermediates. See e.g. [2]<\/a><\/span> for examples.<\/p>\n

References<\/h2>\n
  1. J. Wudarczyk, G. Papamokos, V. Margaritis, D. Schollmeyer, F. Hinkel, M. Baumgarten, G. Floudas, and K. M\u00fcllen, \"Hexasubstituted Benzenes with Ultrastrong Dipole Moments\", Angewandte Chemie International Edition<\/i>, vol. 55, pp. 3220-3223, 2016. https:\/\/doi.org\/10.1002\/anie.201508249<\/a>\n\n<\/li>\n
  2. H.S. Rzepa, \"Routes involving no free C\n <sub>2<\/sub>\n in a DFT-computed mechanistic model for the reported room-temperature chemical synthesis of C\n <sub>2<\/sub>\", Physical Chemistry Chemical Physics<\/i>, vol. 23, pp. 12630-12636, 2021. https:\/\/doi.org\/10.1039\/d1cp02056k<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    Occasionally, someone comments about an old post here, asking a question. Such was the case here, when a question about the dipole moment of cyclopropenylidene arose. It turned out to be 3.5D, but this question sparked a thought about the related molecule below. Of the two resonance forms show above, the one on the left […]<\/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":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},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[],"ppma_author":[2661],"class_list":["post-24027","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\nMolecules with very large dipole moments: cyclopropenium acetylide - 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=24027\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Molecules with very large dipole moments: cyclopropenium acetylide - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Occasionally, someone comments about an old post here, asking a question. Such was the case here, when a question about the dipole moment of cyclopropenylidene arose. It turned out to be 3.5D, but this question sparked a thought about the related molecule below. Of the two resonance forms show above, the one on the left […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2021-07-11T08:54:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-07-21T13:29:16+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.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":"Molecules with very large dipole moments: cyclopropenium acetylide - 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=24027","og_locale":"en_GB","og_type":"article","og_title":"Molecules with very large dipole moments: cyclopropenium acetylide - Henry Rzepa's Blog","og_description":"Occasionally, someone comments about an old post here, asking a question. Such was the case here, when a question about the dipole moment of cyclopropenylidene arose. It turned out to be 3.5D, but this question sparked a thought about the related molecule below. Of the two resonance forms show above, the one on the left […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027","og_site_name":"Henry Rzepa's Blog","article_published_time":"2021-07-11T08:54:36+00:00","article_modified_time":"2021-07-21T13:29:16+00:00","og_image":[{"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.svg","type":"","width":"","height":""}],"author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"Molecules with very large dipole moments: cyclopropenium acetylide","datePublished":"2021-07-11T08:54:36+00:00","dateModified":"2021-07-21T13:29:16+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027"},"wordCount":236,"commentCount":6,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.svg","articleSection":["Interesting chemistry"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027","name":"Molecules with very large dipole moments: cyclopropenium acetylide - Henry Rzepa's Blog","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.svg","datePublished":"2021-07-11T08:54:36+00:00","dateModified":"2021-07-21T13:29:16+00:00","author":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"breadcrumb":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#primaryimage","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.svg","contentUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/07\/C5H2.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"Molecules with very large dipole moments: cyclopropenium acetylide"}]},{"@type":"WebSite","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/","name":"Henry Rzepa's Blog","description":"Chemistry with a twist","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-GB"},{"@type":"Person","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281","name":"Henry Rzepa","image":{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g370be3a7397865e4fd161aefeb0a5a85","url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","caption":"Henry Rzepa"},"description":"Henry Rzepa is Emeritus Professor of Computational Chemistry at Imperial College London.","sameAs":["https:\/\/orcid.org\/0000-0002-8635-8390"],"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?author=1"}]}},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pDef7-6fx","jetpack-related-posts":[{"id":18058,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=18058","url_meta":{"origin":24027,"position":0},"title":"Cyclopropenium cyclopentadienide: a strangely neutral ion-pair?","author":"Henry Rzepa","date":"April 9, 2017","format":false,"excerpt":"Both the cyclopropenium cation and the cyclopentadienide anion are well-known 4n+2-type aromatic ions, but could the two together form an ion-pair? A search of the Cambridge structure database reveals 52 instances of the cyclopropenium cation with a variety of counter-anions, 77 cyclopentadienide\u00a0anions with a variety of counter-cations and one (SOWMOG,\u2026","rel":"","context":"In "crystal_structure_mining"","block_context":{"text":"crystal_structure_mining","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1745"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/04\/SOWMOG-1002x1024.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":24027,"position":1},"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":17252,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17252","url_meta":{"origin":24027,"position":2},"title":"Forking “The most polar neutral compound synthesized” into m-benzyne.","author":"Henry Rzepa","date":"December 21, 2016","format":false,"excerpt":"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\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":13394,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13394","url_meta":{"origin":24027,"position":3},"title":"How many water molecules does it take to ionise HCl?","author":"Henry Rzepa","date":"February 14, 2015","format":false,"excerpt":"According to Guggemos, Slavicek and Kresin, about 5-6!. This is one of those simple ideas, which is probably quite tough to do experimentally. It involved blasting water vapour through a pinhole, adding HCl and\u00a0measuring the dipole-moment induced deflection by an electric field. They\u00a0found\u00a0\"evidence for a noticeable rise in the dipole\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":25633,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=25633","url_meta":{"origin":24027,"position":4},"title":"A new type of bispericyclic reaction: Cyclopropanone + butadiene.","author":"Henry Rzepa","date":"September 30, 2022","format":false,"excerpt":"The term bispericyclic reaction was famously coined by Caramella et al in 2002 to describe the unusual features of the apparently innocuous dimerisation of cyclopentadiene. It shows features of two paths for different pericyclic reactions, comprising a 2+4 cycloaddition in the early stages, but evolving into a (degenerate) pair of\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":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2022\/09\/anomalous.gif?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":7027,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=7027","url_meta":{"origin":24027,"position":5},"title":"Joining up the pieces. Peroxidation of ethyne.","author":"Henry Rzepa","date":"July 9, 2012","format":false,"excerpt":"Sometimes, connections between different areas of chemistry just pop out (without the help of semantic web tools, this is called serendipity). So here, I will try to join up some threads which emerge from previous posts. I had noted that antiaromaticity in cyclopropenium anion is lessened by the system adopting\u2026","rel":"","context":"In "Curly arrows"","block_context":{"text":"Curly arrows","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2327"},"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","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\/24027","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=24027"}],"version-history":[{"count":16,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/24027\/revisions"}],"predecessor-version":[{"id":24066,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/24027\/revisions\/24066"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=24027"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=24027"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=24027"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=24027"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}