{"id":17710,"date":"2017-03-16T17:22:19","date_gmt":"2017-03-16T17:22:19","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=17710"},"modified":"2017-03-17T07:25:03","modified_gmt":"2017-03-17T07:25:03","slug":"how-does-silane-invert-its-configuration","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710","title":{"rendered":"How does silane invert (its configuration)?"},"content":{"rendered":"<div class=\"kcite-section\" kcite-section-id=\"17710\">\n<p>In the <a href=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=17702\">previous post<\/a>, I found intriguing the mechanism by which methane (CH<sub>4<\/sub>) inverts by transposing two of its hydrogens. Here I take a look at silane, SiH<sub>4<\/sub>.<\/p>\n<p>It appears it is a three-stage process! Firstly, silane eliminates molecular hydrogen to form a molecular complex between H<sub>2\u00a0<\/sub>and SiH<sub>2<\/sub> (DOI:\u00a0<a href=\"https:\/\/doi.org\/10.14469\/hpc\/2290\">10.14469\/hpc\/2290<\/a>). The barrier (~60 kcal\/mol) is very much lower than with methane.<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-full wp-image-17715\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/SiH4-elim.gif\" alt=\"\" width=\"450\" \/><a href=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/gaussian-78_tot_ener.svg\"><img decoding=\"async\" class=\"aligncenter size-large wp-image-17718\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/gaussian-78_tot_ener.svg\" alt=\"\" width=\"450\" \/><\/a><a href=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/gaussian-78_tot_ener.svg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-17717\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/gaussian-78_tot_ener.svg\" alt=\"\" width=\"1\" height=\"1\" \/><\/a><\/p>\n<p>The H<sub>2<\/sub> component of this complex then rotates (DOI: <a href=\"https:\/\/doi.org\/10.14469\/hpc\/2289\">10.14469\/hpc\/2289<\/a>) transposing atoms 1 and 2. The barrier for this process is tiny (~4 kcal\/mol).<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-full wp-image-17711\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/SiH4-rot.gif\" alt=\"\" width=\"450\" \/><img decoding=\"async\" class=\"aligncenter size-large wp-image-17709\" src=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/gaussian-27_tot_ener.svg\" alt=\"\" width=\"450\" \/><\/p>\n<p>Finally, the rotated H<sub>2<\/sub>\/SiH<sub>2<\/sub> complex goes back to silane by the first route, but now with the two hydrogens transposed.<\/p>\n<p>So this inversion is a<strong><span style=\"color: #ff0000;\"> stepwise process<\/span><\/strong> in contrast to methane which was<strong><span style=\"color: #ff0000;\"> concerted<\/span><\/strong>, albeit with &#8220;frustrated&#8221; elimination of hydrogen. Again a little molecule can show us so much chemistry, in this case also illustrating the <a href=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=6977\">avoidance of a Woodward-Hoffmann forbidden cheletropic elimination<\/a> by desymmetrisation.<\/p>\n<!-- kcite active, but no citations found -->\n<\/div> <!-- kcite-section 17710 -->","protected":false},"excerpt":{"rendered":"<p>In the previous post, I found intriguing the mechanism by which methane (CH4) inverts by transposing two of its hydrogens. Here I take a look at silane, SiH4. It appears it is a three-stage process! Firstly, silane eliminates molecular hydrogen to form a molecular complex between H2\u00a0and SiH2 (DOI:\u00a010.14469\/hpc\/2290). The barrier (~60 kcal\/mol) is very [&hellip;]<\/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":true,"_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":[1086],"tags":[1395,2066,2063,2068,2067],"ppma_author":[2661],"class_list":["post-17710","post","type-post","status-publish","format-standard","hentry","category-reaction-mechanism-2","tag-chemistry","tag-industrial-gases","tag-methane","tag-sih2-complex","tag-silanes"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How does silane invert (its configuration)? - Henry Rzepa&#039;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=17710\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How does silane invert (its configuration)? - Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"og:description\" content=\"In the previous post, I found intriguing the mechanism by which methane (CH4) inverts by transposing two of its hydrogens. Here I take a look at silane, SiH4. It appears it is a three-stage process! Firstly, silane eliminates molecular hydrogen to form a molecular complex between H2\u00a0and SiH2 (DOI:\u00a010.14469\/hpc\/2290). The barrier (~60 kcal\/mol) is very [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"article:published_time\" content=\"2017-03-16T17:22:19+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2017-03-17T07:25:03+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/SiH4-elim.gif\" \/>\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":"How does silane invert (its configuration)? - Henry Rzepa&#039;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=17710","og_locale":"en_GB","og_type":"article","og_title":"How does silane invert (its configuration)? - Henry Rzepa&#039;s Blog","og_description":"In the previous post, I found intriguing the mechanism by which methane (CH4) inverts by transposing two of its hydrogens. Here I take a look at silane, SiH4. It appears it is a three-stage process! Firstly, silane eliminates molecular hydrogen to form a molecular complex between H2\u00a0and SiH2 (DOI:\u00a010.14469\/hpc\/2290). The barrier (~60 kcal\/mol) is very [&hellip;]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710","og_site_name":"Henry Rzepa&#039;s Blog","article_published_time":"2017-03-16T17:22:19+00:00","article_modified_time":"2017-03-17T07:25:03+00:00","og_image":[{"url":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/SiH4-elim.gif","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=17710#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"How does silane invert (its configuration)?","datePublished":"2017-03-16T17:22:19+00:00","dateModified":"2017-03-17T07:25:03+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710"},"wordCount":156,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2017\/03\/SiH4-elim.gif","keywords":["Chemistry","Industrial gases","Methane","SiH2 complex","Silanes"],"articleSection":["reaction mechanism"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17710","name":"How does silane invert (its configuration)? 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Here I explore an alternative method based instead on computing a molecular\u2026","rel":"","context":"In &quot;reaction mechanism&quot;","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":17702,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17702","url_meta":{"origin":17710,"position":1},"title":"How does methane invert (its configuration)?","author":"Henry Rzepa","date":"March 16, 2017","format":false,"excerpt":"This is a spin-off from the table I constructed here for further chemical examples of the classical\/non-classical norbornyl cation conundrum. One possible entry would include the transition state for inversion of methane via a square planar geometry as compared with e.g. NiH4 for which the square planar motif is its\u2026","rel":"","context":"In &quot;reaction mechanism&quot;","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4930,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=4930","url_meta":{"origin":17710,"position":2},"title":"Molecular Matryoshka dolls","author":"Henry Rzepa","date":"September 20, 2011","format":false,"excerpt":"A Matryoshka doll is better known as a Russian nesting doll. They can have up to eight layers. Molecules can only emulate two layers, although see here for a good candidate for making a three-layered example (the inside layer is C60, which itself might\u00a0encapsulate\u00a0a small molecule. See also \u00a0DOI: 10.1021\/ja991747w).\u2026","rel":"","context":"In &quot;General&quot;","block_context":{"text":"General","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/09\/rebek.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":15823,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=15823","url_meta":{"origin":17710,"position":3},"title":"Real hypervalency in a small molecule.","author":"Henry Rzepa","date":"February 21, 2016","format":false,"excerpt":"Hypervalency is defined as a molecule\u00a0that contains one or more main group elements formally bearing more than eight\u00a0 electrons in their\u00a0 valence shell. One example of a molecule so characterised was CLi6 where the description \"\u201ccarbon can expand its octet of electrons to form this relatively stable molecule\u201c was used.\u2026","rel":"","context":"In &quot;Bond slam&quot;","block_context":{"text":"Bond slam","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2237"},"img":{"alt_text":"CH4","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2016\/02\/CH4.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":4952,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=4952","url_meta":{"origin":17710,"position":4},"title":"The importance of being complete.","author":"Henry Rzepa","date":"September 26, 2011","format":false,"excerpt":"To (mis)quote Oscar Wilde again, \"\u201cTo lose one methyl group may be regarded as a misfortune; to lose both looks like carelessness.\u201d Here, I refer to the (past) tendency of molecular modellers to simplify molecular structures. Thus in 1977, quantum molecular modelling, even at the semi-empirical level, was beset by\u2026","rel":"","context":"In &quot;Interesting chemistry&quot;","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.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/09\/cbdzw1.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":16696,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16696","url_meta":{"origin":17710,"position":5},"title":"A periodic table for anomeric centres, this time with quantified interactions.","author":"Henry Rzepa","date":"August 8, 2016","format":false,"excerpt":"The previous post contained an exploration of the anomeric effect as it occurs at an atom centre X for which the effect is manifest in crystal structures. Here I\u00a0quantify the effect, by selecting the test molecule MeO-X-OMe, where X is of two types:A two-coordinate atom across the series B-O and\u2026","rel":"","context":"In &quot;Interesting chemistry&quot;","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\/17710","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=17710"}],"version-history":[{"count":7,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/17710\/revisions"}],"predecessor-version":[{"id":17722,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/17710\/revisions\/17722"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17710"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=17710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}