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Medientyp:
E-Artikel
Titel:
Cooperativity in alkane‐1,2‐ and 1,3‐polyols: NMR, QTAIM, and IQA study of O─H…OH and C─H…OH bonding interactions
Beteiligte:
Lomas, John S.
Erschienen:
Wiley, 2020
Erschienen in:Magnetic Resonance in Chemistry
Sprache:
Englisch
DOI:
10.1002/mrc.5014
ISSN:
0749-1581;
1097-458X
Entstehung:
Anmerkungen:
Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Proton nuclear magnetic resonance chemical shifts and atom–atom interaction energies for alkanepolyols with 1,2‐diol and 1,3‐diol repeat units, and for their 1:1 pyridine complexes, are computed by density functional theory calculations. In the 1,3‐polyols, based on a tG'Gg' repeat unit, the only important intramolecular hydrogen bonding interactions are O─H<jats:sup>…</jats:sup>OH. By quantum theory of atoms in molecules analysis of the electron density, unstable bond and ring critical points are found for such interactions in 1,2‐polyols with tG'g repeat units, from butane‐1,2,3,4‐tetrol onwards and in their pyridine complexes from propane‐1,2,3‐triol onwards. Several features (OH proton shifts and charges, and interaction energies computed by the interacting quantum atoms approach) are used to monitor the dependence of cooperativity on chain length: This is much less regular in 1,2‐polyols than in 1,3‐polyols and by most criteria has a higher damping factor. Well defined C─H<jats:sup>…</jats:sup>OH interactions are found in butane‐1,2,3,4‐tetrol and higher members of the 1,2‐polyol series, as well as in their pyridine complexes: There is no evidence for cooperativity with O─H<jats:sup>…</jats:sup>OH bonding. For the 1,2‐polyols, there is a tenuous empirical relationship between the existence of a bond critical point for O─H<jats:sup>…</jats:sup>OH hydrogen bonding and the interaction energies of competing exchange channels, but the primary/secondary ratio is always less than unity.</jats:p>