{"id":27055,"date":"2024-05-20T15:01:15","date_gmt":"2024-05-20T14:01:15","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=27055"},"modified":"2024-05-22T09:50:46","modified_gmt":"2024-05-22T08:50:46","slug":"possible-formation-of-an-impossible-molecule","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=27055","title":{"rendered":"Possible Formation of an Impossible Molecule?"},"content":{"rendered":"
\n

In the previous post<\/a>, I explored the so-called “impossible” molecule methanetriol. It is regarded as such because the equilbrium resulting in loss of water is very facile, being exoenergic by ~14 kcal\/mol in free energy. Here I explore whether changing the substituent\u00a0R could result in suppressing the loss of water and stabilising the triol.
\n\"\"<\/a>
\nI started (as I usually do) with a search for crystal structures, in this case containing the motif shown below (trisubstituted carbon, disubstituted oxygen and \u00a0R = H or C and any type of connecting bond), which is the species resulting from loss of R–<\/sup> to form a trihydroxycarbenium cation.
\n\"\"<\/p>\n

This produces six hits, of which \u00a0HIWQEJ[1]<\/a><\/span> (DOI: 10.5517\/cc3k560<\/a>) and UYOYUD[2]<\/a><\/span> (DOI: 10.5517\/ccvrghj<\/a>) are both salts of trihydroxycarbenium cation (or protonated carbonic acid) itself – the counter\u00a0ion being eg AsF6<\/sub> or an iron system. So R needs to be a stable anion and two obvious groups are triflate (trifluoromethylsulfonate) or bis(trifluoromethanesulfonyl)azanide.<\/p>\n

The triflate (R=CF3<\/sub>SO2<\/sub>-O) shown below has an unusually long predicted C-O bond (1.620\u00c5), which suggests the system is already partially ionised as shown in the top diagram. An \u03c9B97X-D calculation [3]<\/a><\/span>, DOI: 10.14469\/hpc\/14280<\/a>) reveals the species shown below is +6.6 kcal\/mol higher in free energy than the one corresponding to loss of water.<\/p>\n

\"\"
\nBis-triflamide (bis(trifluoromethanesulfonyl)azanide) goes further, helped no doubt by the formation of a second strong hydrogen bond between the two ions. It is now -11.8 kcal\/mol lower in free energy compared to the species resulting from loss of water.<\/p>\n

\"\"<\/p>\n

So that is my candidate for a “possible”\u00a0impossible molecule. Any takers for its synthesis?<\/p>\n

\n

Postscript:<\/b> The next higher homologue, tris(trifluoromethanesulfonyl)methanide anion + trihydroxycarbenium cation is similar to the bis-triflamide in being -12.1 kcal\/mol lower than the species resulting from loss of water. <\/p>\n

\n

References<\/h2>\n
  1. R. Minkwitz, and S. Schneider, \"Trihydroxycarbenium Hexafluorometalates: Salts of Protonated Carbonic Acid\", Angewandte Chemie International Edition<\/i>, vol. 38, pp. 714-715, 1999. https:\/\/doi.org\/10.1002\/(sici)1521-3773(19990301)38:5<714::aid-anie714>3.0.co;2-k<\/a>\n\n<\/li>\n
  2. S. Guo, J. Lin, W. Chen, X. Wei, J. Wang, and W. Dong, \"CCDC 797118: Experimental Crystal Structure Determination\", 2011. https:\/\/doi.org\/10.5517\/ccvrghj<\/a>\n\n<\/li>\n
  3. H. Rzepa, \"Possible Formation of an Impossible Molecule?\", 2024. https:\/\/doi.org\/10.14469\/hpc\/14280<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    In the previous post, I explored the so-called “impossible” molecule methanetriol. It is regarded as such because the equilbrium resulting in loss of water is very facile, being exoenergic by ~14 kcal\/mol in free energy. Here I explore whether changing the substituent\u00a0R could result in suppressing the loss of water and stabilising the triol. I […]<\/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":[],"tags":[],"ppma_author":[2661],"class_list":["post-27055","post","type-post","status-publish","format-standard","hentry"],"yoast_head":"\nPossible Formation of an Impossible Molecule? - 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=27055\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Possible Formation of an Impossible Molecule? - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"In the previous post, I explored the so-called “impossible” molecule methanetriol. It is regarded as such because the equilbrium resulting in loss of water is very facile, being exoenergic by ~14 kcal\/mol in free energy. Here I explore whether changing the substituent\u00a0R could result in suppressing the loss of water and stabilising the triol. I […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=27055\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2024-05-20T14:01:15+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-05-22T08:50:46+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/05\/methanetriol2.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=\"3 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Possible Formation of an Impossible Molecule? - 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=27055","og_locale":"en_GB","og_type":"article","og_title":"Possible Formation of an Impossible Molecule? - Henry Rzepa's Blog","og_description":"In the previous post, I explored the so-called “impossible” molecule methanetriol. It is regarded as such because the equilbrium resulting in loss of water is very facile, being exoenergic by ~14 kcal\/mol in free energy. Here I explore whether changing the substituent\u00a0R could result in suppressing the loss of water and stabilising the triol. 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An example of Octopus publishing?","author":"Henry Rzepa","date":"August 15, 2021","format":false,"excerpt":"Whilst I was discussing the future of scientific publication in the last post, a debate was happening behind the scenes regarding the small molecule cyclopropenylidene. This is the smallest known molecule displaying\u00a0\u03c0-aromaticity, but its high reactivity means that it is unlikely to be isolated in the condensed phase. A question\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\/2021\/08\/Screenshot-814-1024x792.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":24483,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24483","url_meta":{"origin":27055,"position":2},"title":"Protein-Biotin complexes. Crystal structure mining.","author":"Henry Rzepa","date":"December 12, 2021","format":false,"excerpt":"In the previous post, I showed some of the diverse \"non-classical\"interactions between Biotin and a protein where it binds very strongly. Here I take a look at two of these interactions to discover how common they are in small molecule structures. The first search is of a CH hydrogen bond\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\/2021\/12\/Screenshot-983-1024x893.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":221,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=221","url_meta":{"origin":27055,"position":3},"title":"How do molecules interact with each other?","author":"Henry Rzepa","date":"April 12, 2009","format":false,"excerpt":"Understanding how molecules interact (bind) with each other when in close proximity is essential in all areas of chemistry. One specific example of this need is for the molecule shown below. This is the so-called Pirkle Reagent and is much used to help resolve the two enantiomers of a racemic\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":"The Pirkle reagent","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/pirkle.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":23434,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23434","url_meta":{"origin":27055,"position":4},"title":"Deltamethrin – a polymorphed insecticide.","author":"Henry Rzepa","date":"March 24, 2021","format":false,"excerpt":"Deltamethin is a pyrethroid insecticide for control of malaria which has been used for a little while. Perhaps inevitably, mosquitoes are developing resistance to it. So what could be done about countering this? Well, perhaps surprisingly, form a polymorph!\u00a0These crystal structure isomers are often highly undesirable; thus\u00a0Ritonavir, which changed 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":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/03\/Screenshot-643-1024x716.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":24027,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=24027","url_meta":{"origin":27055,"position":5},"title":"Molecules with very large dipole moments: cyclopropenium acetylide","author":"Henry Rzepa","date":"July 11, 2021","format":false,"excerpt":"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,\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\/2021\/07\/C5H5-esp-1024x690.jpg?resize=350%2C200&ssl=1","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\/27055","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=27055"}],"version-history":[{"count":27,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/27055\/revisions"}],"predecessor-version":[{"id":27089,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/27055\/revisions\/27089"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=27055"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=27055"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=27055"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=27055"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}