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dc.contributor.authorHe, Menfang
dc.contributor.authorPiscelli, Bruno
dc.contributor.authorCormanich , Rodrigo
dc.contributor.authorO'Hagan, David
dc.identifier.citationHe , M , Piscelli , B , Cormanich , R & O'Hagan , D 2024 , ' Conformational analysis explores the role of electrostatic non-classical CFHC hydrogen bonding interactions in selectively halogenated cyclohexanes ' , The Journal of Organic Chemistry , vol. 89 , no. 6 , pp. 4009–4018 .
dc.identifier.otherORCID: /0000-0002-0510-5552/work/155069028
dc.descriptionFunding: Fundação de Amparo à Pesquisa do Estado de São Paulo - 2018/03910-1, 2023/14064-2; China Scholarship Council; Fundo de Apoio ao Ensino, à Pesquisa e Extensão, Universidade Estadual de Campinas - 3472/23en
dc.description.abstractThe conformational equilibria of selectively halogenated cyclohexanes are explored both experimentally (VT-NMR) for 1,1,4,-trifluorocyclohexane 7 and by computational analysis (M06-2X/aug-cc-pVTZ level), with the latter approach extending to a wider range of more highly fluorinated cyclohexanes. Perhaps unexpectedly, 7ax is preferred over the 7eq conformation by ΔG = 1.06 kcal mol–1, contradicting the accepted norm for substituents on cyclohexanes. The axial preference is stronger again in 1,1,3,3,4,5,5,-heptafluorocyclohexane 9 (ΔG = 2.73 kcal mol–1) as the CF2 groups further polarize the isolated CH2 hydrogens. Theoretical decomposition of electrostatic and hyperconjugative effects by natural bond orbital analysis indicated that nonclassical hydrogen bonding (NCHB) between the C-4 fluorine and the diaxial hydrogens at C-2 and C-6 in cyclohexane 7 and 9 largely accounts for the observed bias. The study extended to changing fluorine (F) for chlorine (Cl) and bromine (Br) at the pseudoanomeric position in the cyclohexanes. Although these halogens do not become involved in NCHBs, they polarize the geminal −CHX– hydrogen at the pseudoanomeric position to a greater extent than fluorine, and consequent electrostatic interactions influence conformer stabilities.
dc.relation.ispartofThe Journal of Organic Chemistryen
dc.subjectQD Chemistryen
dc.titleConformational analysis explores the role of electrostatic non-classical CFHC hydrogen bonding interactions in selectively halogenated cyclohexanesen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. Institute of Behavioural and Neural Sciencesen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.contributor.institutionUniversity of St Andrews. Biomedical Sciences Research Complexen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.description.statusPeer revieweden

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