{"id":28615,"date":"2025-05-20T09:56:50","date_gmt":"2025-05-20T08:56:50","guid":{"rendered":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615"},"modified":"2025-05-29T12:06:28","modified_gmt":"2025-05-29T11:06:28","slug":"5-imino-5%ce%bb4-heptathiepane-3-oxide-more-exuberent-anomeric-effects","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615","title":{"rendered":"5-Imino-5\u03bb4<\/sup>-heptathiepane 3-oxide. More exuberent anomeric effects."},"content":{"rendered":"
\n

The two previous \u00a0posts[1]<\/a><\/span>,[2]<\/a><\/span> on the topic of anomeric effects in 7-membered sulfur rings illustrated how orbital interactions between the lone pairs in the molecules and S-S bonds produced widely varying S-S bond lengths in the molecules, some are shorter than normal (which is ~2.05\u00c5 for e.g.<\/em> the S8<\/sub> ring) by ~ 0.1\u00c5 and some are longer by ~0.24\u00c5. Here we extend this to the unknown molecule shown below.<\/p>\n

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

The usual\u00a0MN15L\/Def2-TZVPP calculation[3]<\/a><\/span> gives the calculated geometry shown below. In parentheses are the calculated S-S vibrational wavenumbers (some are marked with ~ since these modes are contaminated by mixing with other parts of the molecules).<\/p>\n

\"\"<\/p>\n

The interaction energies between the donor and acceptor, E(2), are shown below. Numbers 5-8 are the same as was identified for the parent molecule S7<\/sub>, but the energies have increased substantially (previously 12.3\/10.1 kcal\/mol). The Wiberg bond index for the strongest bond (S2-S3) is 1.276 and the weakest (S1-S2) is 0.610, quite some variation! Given that the known S7<\/sub>O was already very unstable[4]<\/a><\/span>, it seems unlikely that the probably even more unstable S7<\/sub>ONH could ever be isolated, but there is a challenge!<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
#<\/th>\nAcceptor S-S bond<\/th>\nDonor Lp<\/th>\nNBO E(2) Energy<\/th>\n<\/tr>\n
1<\/td>\nS4-S5<\/td>\nO8<\/td>\n31.9<\/td>\n<\/tr>\n
2<\/td>\nS1-S2<\/td>\nN9<\/td>\n29.6<\/td>\n<\/tr>\n
3<\/td>\nS1-S6<\/td>\nN9<\/td>\n27.0<\/td>\n<\/tr>\n
4<\/td>\nS5-S6<\/td>\nO8<\/td>\n20.4<\/td>\n<\/tr>\n
5<\/td>\nS4-S5<\/td>\nS7<\/td>\n16.8<\/td>\n<\/tr>\n
6<\/td>\nS1-S2<\/td>\nS3<\/td>\n16.4<\/td>\n<\/tr>\n
7<\/td>\nS3-S7<\/td>\nS2<\/td>\n15.4<\/td>\n<\/tr>\n
8<\/td>\nS3-S7<\/td>\nS4<\/td>\n15.2<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

There are numerous compounds with six, seven and eight membered sulfur rings, and it would always be worth keeping an eye out for unusually short or long S-S bonds in them, since they may well be more manifestations of these sulfur anomeric effects.<\/p>\n

References<\/h2>\n
  1. H. Rzepa, \"Cycloheptasulfur sulfoxide, S<sub>7<\/sub>O \u2013 Anomeric effects galore!\", 2025. https:\/\/doi.org\/10.59350\/rzepa.28515<\/a>\n\n<\/li>\n
  2. H. Rzepa, \"Cyclo-Heptasulfur, S<sub>7<\/sub> \u2013 a classic anomeric effect discovered during a pub lunch!\", 2025. https:\/\/doi.org\/10.59350\/rzepa.28407<\/a>\n\n<\/li>\n
  3. H. Rzepa, \"S7O2 NBO7 Cs symmetry\", 2025. https:\/\/doi.org\/10.14469\/hpc\/15235<\/a>\n\n<\/li>\n
  4. R. Steudel, R. Reinhardt, and T. Sandow, \"Bond Interaction in Sulfur Rings: Crystal and Molecular Structure of <i>cyclo<\/i>\u2010Heptasulfur Oxide, S<sub>7<\/sub>O\", Angewandte Chemie International Edition in English<\/i>, vol. 16, pp. 716-716, 1977. https:\/\/doi.org\/10.1002\/anie.197707161<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    The two previous \u00a0posts, on the topic of anomeric effects in 7-membered sulfur rings illustrated how orbital interactions between the lone pairs in the molecules and S-S bonds produced widely varying S-S bond lengths in the molecules, some are shorter than normal (which is ~2.05\u00c5 for e.g. the S8 ring) by ~ 0.1\u00c5 and some […]<\/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-28615","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\n5-Imino-5\u03bb4-heptathiepane 3-oxide. More exuberent anomeric effects. - 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=28615\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"5-Imino-5\u03bb4-heptathiepane 3-oxide. 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More exuberent anomeric effects. - Henry Rzepa's Blog","og_description":"The two previous \u00a0posts, on the topic of anomeric effects in 7-membered sulfur rings illustrated how orbital interactions between the lone pairs in the molecules and S-S bonds produced widely varying S-S bond lengths in the molecules, some are shorter than normal (which is ~2.05\u00c5 for e.g. the S8 ring) by ~ 0.1\u00c5 and some […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615","og_site_name":"Henry Rzepa's Blog","article_published_time":"2025-05-20T08:56:50+00:00","article_modified_time":"2025-05-29T11:06:28+00:00","author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28615"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"5-Imino-5\u03bb4-heptathiepane 3-oxide. 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Each oxygen itself bears two bonds and has two lone pairs, and either of these can align with one of three other C-O bonds to generate an anomeric\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2024\/04\/Screenshot-304.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":28639,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28639","url_meta":{"origin":28615,"position":2},"title":"S7I1+: The largest anomeric effect exhibited by sulfur.","author":"Henry Rzepa","date":"May 21, 2025","format":false,"excerpt":"In this series of posts about the electronic effects in small sulfur rings I have explored increasingly large induced geometric effects. Here is the largest so far, for the compound S7I1+ The calculated geometry is shown below, with the crystallographic values in parentheses - the two matching very well. The\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":28773,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28773","url_meta":{"origin":28615,"position":3},"title":"Cyclo-S6 (Hexathiane) – anomeric effects again!","author":"Henry Rzepa","date":"June 1, 2025","format":false,"excerpt":"I thought I was done with exploring anomeric effects in small sulfur rings. However, I then realised that all the systems\u00a0that I had described had an odd number of atoms and that I had not looked at any even numbered rings. Thus hexasulfur is a smaller (known) ring version of\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":29665,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=29665","url_meta":{"origin":28615,"position":4},"title":"Alternative reactions of the N\u2261N “triple bond” in a nitric oxide dimer: forming the trimer N3O3.","author":"Henry Rzepa","date":"September 3, 2025","format":false,"excerpt":"In the previous post I mooted the possibility that a high energy form of the dimer of nitric oxide 1 might nonetheless be able to be detected using suitable traps (such as hydrogenation or cycloaddition). However, an interesting alternative is that this species could be trapped by nitric oxide itself.\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":31140,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31140","url_meta":{"origin":28615,"position":5},"title":"The fast disappearance of hydroxycarbene through hydrogen tunnelling – or is it really tunnelling?","author":"Henry Rzepa","date":"April 11, 2026","format":false,"excerpt":"In 2008, the previously elusive hydroxycarbene, H-C-OH was finally reported as having been captured by matrix isolation, accompanied by the observation that \"we unexpectedly find that H\u2013C\u2013OH rearranges to formaldehyde with a half-life of only 2h at 11K by pure hydrogen tunnelling through a large energy barrier in excess of\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","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\/28615","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=28615"}],"version-history":[{"count":23,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28615\/revisions"}],"predecessor-version":[{"id":28755,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/28615\/revisions\/28755"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28615"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28615"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28615"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=28615"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}