The Standard Enthalpies of Formation of B(CH3)3, B(C2H5)3, B2(CH3)6, and B2(C2H5)6 Determined Using the Calibration Dependencies, as Well as Their Thermodynamic Properties

The Standard Enthalpies of Formation of B(CH3)3, B(C2H5)3, B2(CH3)6, and B2(C2H5)6 Determined Using the Calibration Dependencies, as Well as Their Thermodynamic Properties | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Standard Enthalpies of Formation of B(CH3)3, B(C2H5)3, B2(CH3)6, and B2(C2H5)6 Determined Using the Calibration Dependencies, as Well as Their Thermodynamic Properties Poskrebyshev G.A., Frolov S.M. This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9417424/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract In this study, the most thermochemically stable structures of monomers and dimers of pyrophoric organoboron compounds (X = B(CH 3 ) 3 (TMB), B 2 (CH 3 ) 6 (DTMB), B(C 2 H 5 ) 3 (TEB), B 2 (C 2 H 5 ) 6 (DTEB), B(C 3 H 7 ) 3 , B(C 4 H 9 ) 3 , and their isomers) are determined using quantum-chemical calculations (M062X (i = 1), CBS-QB3 (i = 2), and G3B3 (i = 3)). Their calculated values of H o (X) i are used to verify the consistency of the literature values of Δ f H o (X) lit . Based on the results of comparing the calculated and literature thermochemistry of homodesmotic reactions involving B(i-C 3 H 7 ) 3 , B(sec-C 4 H 9 ) 3 , and B(tert-C 4 H 9 ) 3 , the significant difference between them is concluded, while for the other examined compounds, the calculated and literature values are in good agreement. The latter are used to determine linear calibration relationships (Δ ra H o (X) lit = A i + B i × Δ ra H o (X) i_calc ) between calculated and literature values of standard atomization enthalpies (Δ ra H o (X) i_calc and Δ ra H o (X) lit ), which are used to determine recommended values Δ ra H o (X) i_rec and Δ f H o (X) i_rec (Δ ra H o (X) i_rec = A i + B i × Δ ra H o (X) i_calc ), as well as their errors (SD i ). The values of Δ f H o (B 2 (CH 3 ) 6 ) rec = -185.7 ± 18 kJ/mol and Δ f H o (B 2 (C 2 H 5 ) 6 ) rec = -229.8 ± 18 kJ/mol, determined for the first time, demonstrate the exothermicity and exergonicity of their dissociation reactions (Δ r1 H o = -65.1 kJ/mol and Δ r2 H o = -91.6 kJ/mol). The temperature dependencies of the corresponding values of Δ r1 G o and Δ r2 G o indicate the almost complete dissociation of the dimers even at T < 300 K and negligible contribution of the dimer to the heat of combustion of TMB and TEB. Thermodynamics and statistical mechanics trimethylborane (TMB) triethylborane (TEB) dimer enthalpy of formation CBSQB3 G3B3 M062X Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9417424","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":623425597,"identity":"eca68e74-6ff4-4f97-b03d-7e8d2a84d3f6","order_by":0,"name":"Poskrebyshev G.A.","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyElEQVRIiWNgGAWjYJACxgYGGwYDBh7StKSRruUwCVrko5sPf5y557y8uXTvAeaKmjoG8xkJ+LUY3jmWJrnh2W3DnXPOJTCeOXaYQeYGIS0zcswYHxy4nWBwI8eAsYHtAIOEBGEtxh8fHDgH1fKvjrAWeYkcA8kNBw5AtDS2MRPWYiAD9MuMA8mGG+6cMTjY2HeYR4LnAQFbZgNDrOeAnbzB7R7Dhw3f6uQk2AnZcgPGkmBgOACkCMeO/AwkLaNgFIyCUTAKsAIAB31GAaGgRWYAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-8920-7037","institution":"Semenov Institute of Chemical Physics","correspondingAuthor":true,"prefix":"","firstName":"Poskrebyshev","middleName":"","lastName":"G.A.","suffix":""},{"id":623425598,"identity":"26a213fe-00e2-46ac-a98e-7966dc098422","order_by":1,"name":"Frolov S.M.","email":"","orcid":"https://orcid.org/0000-0002-1705-8327","institution":"Semenov Institute of Chemical Physics","correspondingAuthor":false,"prefix":"","firstName":"Frolov","middleName":"","lastName":"S.M.","suffix":""}],"badges":[],"createdAt":"2026-04-14 15:35:14","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9417424/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-9417424/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108634920,"identity":"349eacbb-3a8a-48b4-b998-b7505ccf6501","added_by":"auto","created_at":"2026-05-06 17:39:01","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":773195,"visible":true,"origin":"","legend":"","description":"","filename":"TEBversion04JTAC.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9417424/v2_covered_f00c0aee-978a-4994-95a1-e96500e25b23.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"The Standard Enthalpies of Formation of B(CH3)3, B(C2H5)3, B2(CH3)6, and B2(C2H5)6 Determined Using the Calibration Dependencies, as Well as Their Thermodynamic Properties","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Semenov Institute of Chemical Physics","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"trimethylborane (TMB), triethylborane (TEB), dimer, enthalpy of formation, CBSQB3, G3B3, M062X","lastPublishedDoi":"10.21203/rs.3.rs-9417424/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9417424/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, the most thermochemically stable structures of monomers and dimers of pyrophoric organoboron compounds (X\u0026thinsp;=\u0026thinsp;B(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e (TMB), B\u003csub\u003e2\u003c/sub\u003e(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003e (DTMB), B(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e (TEB), B\u003csub\u003e2\u003c/sub\u003e(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003e (DTEB), B(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e, B(C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e9\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e, and their isomers) are determined using quantum-chemical calculations (M062X (i\u0026thinsp;=\u0026thinsp;1), CBS-QB3 (i\u0026thinsp;=\u0026thinsp;2), and G3B3 (i\u0026thinsp;=\u0026thinsp;3)). Their calculated values of \u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei\u003c/sub\u003e are used to verify the consistency of the literature values of Δ\u003csub\u003ef\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003elit\u003c/sub\u003e. Based on the results of comparing the calculated and literature thermochemistry of homodesmotic reactions involving B(i-C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e, B(sec-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e9\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e, and B(tert-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e9\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e, the significant difference between them is concluded, while for the other examined compounds, the calculated and literature values are in good agreement. The latter are used to determine linear calibration relationships (Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csub\u003eo\u003c/sub\u003e(X)\u003csub\u003elit\u003c/sub\u003e = A\u003csub\u003ei\u003c/sub\u003e + B\u003csub\u003ei\u003c/sub\u003e\u0026thinsp;\u0026times;\u0026thinsp;Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_calc\u003c/sub\u003e) between calculated and literature values of standard atomization enthalpies (Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_calc\u003c/sub\u003e and Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003elit\u003c/sub\u003e), which are used to determine recommended values Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_rec\u003c/sub\u003e and Δ\u003csub\u003ef\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_rec\u003c/sub\u003e (Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_rec\u003c/sub\u003e = A\u003csub\u003ei\u003c/sub\u003e + B\u003csub\u003ei\u003c/sub\u003e\u0026thinsp;\u0026times;\u0026thinsp;Δ\u003csub\u003era\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(X)\u003csub\u003ei_calc\u003c/sub\u003e), as well as their errors (SD\u003csub\u003ei\u003c/sub\u003e).\u003c/p\u003e \u003cp\u003eThe values of Δ\u003csub\u003ef\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(B\u003csub\u003e2\u003c/sub\u003e(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003e)\u003csub\u003erec\u003c/sub\u003e = -185.7\u0026thinsp;\u0026plusmn;\u0026thinsp;18 kJ/mol and Δ\u003csub\u003ef\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e(B\u003csub\u003e2\u003c/sub\u003e(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003e)\u003csub\u003erec\u003c/sub\u003e = -229.8\u0026thinsp;\u0026plusmn;\u0026thinsp;18 kJ/mol, determined for the first time, demonstrate the exothermicity and exergonicity of their dissociation reactions (Δ\u003csub\u003er1\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e = -65.1 kJ/mol and Δ\u003csub\u003er2\u003c/sub\u003e\u003cem\u003eH\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e = -91.6 kJ/mol). The temperature dependencies of the corresponding values of Δ\u003csub\u003er1\u003c/sub\u003e\u003cem\u003eG\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e and Δ\u003csub\u003er2\u003c/sub\u003e\u003cem\u003eG\u003c/em\u003e\u003csup\u003eo\u003c/sup\u003e indicate the almost complete dissociation of the dimers even at \u003cem\u003eT\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;300 K and negligible contribution of the dimer to the heat of combustion of TMB and TEB.\u003c/p\u003e","manuscriptTitle":"The Standard Enthalpies of Formation of B(CH3)3, B(C2H5)3, B2(CH3)6, and B2(C2H5)6 Determined Using the Calibration Dependencies, as Well as Their Thermodynamic Properties","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2026-05-06 17:38:11","doi":"10.21203/rs.3.rs-9417424/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2026-04-15 07:44:25","doi":"10.21203/rs.3.rs-9417424/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"56878c4a-6225-45a4-9ae8-682ff60b5071","owner":[],"postedDate":"May 6th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":66347396,"name":"Thermodynamics and statistical mechanics"}],"tags":[],"updatedAt":"2026-04-15T07:44:26+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-06 17:38:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v2","identity":"rs-9417424","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9417424","identity":"rs-9417424","version":["v2"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}