{"id":22971,"date":"2020-11-07T12:13:33","date_gmt":"2020-11-07T12:13:33","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=22971"},"modified":"2021-04-01T06:29:22","modified_gmt":"2021-04-01T05:29:22","slug":"a-new-example-of-a-quadruple-bond-from-carbon-to-fe","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=22971","title":{"rendered":"A new example of a quadruple bond from carbon – to Fe."},"content":{"rendered":"
\n

Way back in 2010, I was writing<\/a> about an experience I had just had during an organic chemistry tutorial, which morphed into speculation as to whether a carbon atom might sustain a quadruple bond to nitrogen. A decade on, and possibly approaching 100 articles by many authors on the topic, quadruple bonds to carbon continue to fascinate. Now an article as appeared[1]<\/a><\/span> repeating this speculation for a carbon to iron quadruple bond,‡<\/sup> in the very simple species C\u2a78Fe(CO)3<\/sub> (see also a Rh-B equivalent[2]<\/a><\/span>). This is particularly exciting because of the very real prospect of synthesising this species and perchance getting a crystal structure (something not possible with most of the other quadruply bonded carbon systems studied to date).<\/p>\n

They authors report[1]<\/a><\/span> that this sytem is well described by a single-configurational wavefunction and hence that a M062X\/Def2-TZVPP calculation is a good description of the bonding. In the article you will find the valence molecular orbitals shown, which by their nature show a lot of delocalisation. Because the more localised NBOs are not shown in the article, I illustrate them here, as 3D rotatable models. The DOI for the calculation can be found at\u00a010.14469\/hpc\/7537<\/a>.<\/p>\n\n\n\n\n\n\n\n
CFe(CO)3<\/sub><\/th>\n<\/tr>\n
NBO 37 π<\/th>\nNBO 36 π<\/th>\n<\/tr>\n
\n
\"\"

Click to view 3D model of NBO 37<\/p><\/div>\n<\/td>\n

\n
\"\"

Click to view 3D model of NBO 36<\/p><\/div>\n<\/td>\n<\/tr>\n

NBO 33 σ<\/th>\nNBO 23 σ<\/th>\n<\/tr>\n
\n
\"\"

Click to view 3D model of NBO 33<\/p><\/div>\n<\/td>\n

\n
\"\"

Click to view 3D model of NBO 23<\/p><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

These NBOs show very clearly that the two higher energy orbitals are orthogonal \u03c0-bonds to carbon from Fe and the two lower energy orbitals are both \u03c3-bonds to carbon from Fe. Exactly the same picture appears for C2<\/sub>, which has been often mentioned<\/a> on this blog.<\/p>\n

All that remains is that some inspired synthetic chemist sets out to make C\u2a78Fe(CO)3<\/sub> and to report back on its properties. I fancy the last has not yet been heard about quadruple bonds to carbon!<\/p>\n

\n

Postscript:<\/b> Here are the analogous orbitals for the species N\u2a78Mn(CO)3<\/sub> to illustrate their evolution across an isoelectronic series.<\/p>\n\n\n\n\n\n\n\n
NMn(CO)3<\/sub><\/th>\n<\/tr>\n
NBO 35<\/th>\nNBO 34<\/th>\n<\/tr>\n
\n
\"\"

Click to view 3D model of NBO 35<\/p><\/div>\n<\/td>\n

\n
\"\"

Click to view 3D model of NBO 34<\/p><\/div>\n<\/td>\n<\/tr>\n

NBO 33<\/th>\nNBO 20<\/th>\n<\/tr>\n
\n
\"\"

Click to view 3D model of NBO 33<\/p><\/div>\n<\/td>\n

\n
\"\"

Click to view 3D model of NBO 20<\/p><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

NBO 33 (the higher in energy of the two σ-type bonds) has an interesting structure. Here it is at a slightly lower threshold:<\/p>\n

\"\"

Click to view 3D model of NBO 33 for NMn(CO)3 at threshold 0.015au<\/p><\/div>\n

It has an inner compact σ-bond running along the axis of the bond and an outer “wrap” of different phase. A two layer σ-bond if you like!<\/p>\n

\n

‡<\/sup>This was one of the shortlisted candidates for Molecule of the Year, 2020.<\/a> See also[3]<\/a><\/span><\/p>\n

References<\/h2>\n
  1. A.J. Kalita, S.S. Rohman, C. Kashyap, S.S. Ullah, and A.K. Guha, \"Transition metal carbon quadruple bond: viability through single electron transmutation\", Physical Chemistry Chemical Physics<\/i>, vol. 22, pp. 24178-24180, 2020. https:\/\/doi.org\/10.1039\/d0cp03436c<\/a>\n\n<\/li>\n
  2. L.F. Cheung, T. Chen, G.S. Kocheril, W. Chen, J. Czekner, and L. Wang, \"Observation of Four-Fold Boron\u2013Metal Bonds in RhB(BO<sup>\u2013<\/sup>) and RhB\", The Journal of Physical Chemistry Letters<\/i>, vol. 11, pp. 659-663, 2020. https:\/\/doi.org\/10.1021\/acs.jpclett.9b03484<\/a>\n\n<\/li>\n
  3. A.J. Kalita, S.S. Rohman, C. Kashyap, S.S. Ullah, I. Baruah, L.J. Mazumder, P.P. Sahu, and A.K. Guha, \"Is a transition metal\u2013silicon quadruple bond viable?\", Physical Chemistry Chemical Physics<\/i>, vol. 23, pp. 9660-9662, 2021. https:\/\/doi.org\/10.1039\/d1cp00598g<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    Way back in 2010, I was writing about an experience I had just had during an organic chemistry tutorial, which morphed into speculation as to whether a carbon atom might sustain a quadruple bond to nitrogen. A decade on, and possibly approaching 100 articles by many authors on the topic, quadruple bonds to carbon continue […]<\/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_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":[],"ppma_author":[2661],"class_list":["post-22971","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry"],"yoast_head":"\nA new example of a quadruple bond from carbon - to Fe. - 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=22971\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A new example of a quadruple bond from carbon - to Fe. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Way back in 2010, I was writing about an experience I had just had during an organic chemistry tutorial, which morphed into speculation as to whether a carbon atom might sustain a quadruple bond to nitrogen. 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The rational\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":23686,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23686","url_meta":{"origin":22971,"position":2},"title":"A reality-based suggestion for a molecule with a metal M\u2a78N quadruple bond.","author":"Henry Rzepa","date":"May 13, 2021","format":false,"excerpt":"I noted in an earlier post the hypothesized example of (CO)3Fe\u2a78C as exhibiting a carbon to iron quadruple bond and which might have precedent in known five-coordinate metal complexes where one of the ligands is a \"carbide\" or C ligand. I had previously mooted that the Fe\u2a78C combination might be\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\/05\/Screenshot-703-1024x818.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":9973,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=9973","url_meta":{"origin":22971,"position":3},"title":"A (very) short history of shared-electron bonds.","author":"Henry Rzepa","date":"March 26, 2013","format":false,"excerpt":"The concept of a shared electron bond and its property of an order is almost 100 years old in modern form, when G. N. Lewis suggested a model for single and double bonds that involved sharing either 2 or 4 electrons between a pair of atoms. We tend to think\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":"Click for 3D","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/03\/PYRDRE.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":20933,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=20933","url_meta":{"origin":22971,"position":4},"title":"Startling bonds: revisiting C\u2a78N+, via the helium bond in N\u2261C-He+.","author":"Henry Rzepa","date":"May 27, 2019","format":false,"excerpt":"Although the small diatomic molecule known as dicarbon or C2 has been known for a long time, its properties and reactivity have really only been determined\u00a0via its very high temperature generation. My interest started in 2010, when I speculatively proposed here that the related isoelectronic species C\u2a78N+ might sustain 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":"","width":0,"height":0},"classes":[]},{"id":10733,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10733","url_meta":{"origin":22971,"position":5},"title":"Is dicarbon (C2) a molecule of chemical interest?","author":"Henry Rzepa","date":"July 3, 2013","format":false,"excerpt":"C2\u00a0(dicarbon) is certainly interesting from a theoretical point of view. Whether or not it can be described as having a quadruple bond has induced much passionate discussion,,,. Its occurrence in space and in flames is also well-known. But does it have what might be called a conventional chemistry? Other highly\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":"Click for 3D","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/07\/LaOsC1.jpeg?resize=350%2C200","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","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\/22971","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=22971"}],"version-history":[{"count":29,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/22971\/revisions"}],"predecessor-version":[{"id":23521,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/22971\/revisions\/23521"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=22971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=22971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=22971"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=22971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}