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Improper Hydrogen CH⋅⋅⋅O Bonds Cause Self‐Association of α,β‐Enaminoketones Containing Fluorosubstituted Alkyl Groups
Author(s) -
Wójcik Jacek,
KamienskaTrela Krystyna,
Pecul Magdalena,
BartoszakAdamska Elzbieta,
Vdovienko Siergiej I.,
Gerus Igor I.
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200300937
Subject(s) - chemistry , hydrogen bond , intermolecular force , antiparallel (mathematics) , crystallography , ab initio , ab initio quantum chemistry methods , alkyl , alkoxy group , proton nmr , carbon 13 nmr , stereochemistry , computational chemistry , molecule , organic chemistry , physics , quantum mechanics , magnetic field
Abstract Concentration‐ and temperature‐dependent IR, NMR and dipole‐moment studies on 4‐N,N‐dimethylamino‐1,1,1‐trifluoro‐3‐buten‐2‐one and two of its higher homologues showed that these compounds undergo reversible dimerization in nonpolar solvents. Antiparallel “closed” dimers are formed with a network of improper intermolecular CH⋅⋅⋅O hydrogen bonds. Quantitative analysis of the 1 H NMR data yielded Δ H 0 =−17.6 kJ mol −1 and Δ S 0 =‐46.9 J deg −1 mol −1 . The interactions observed are the strongest among those involving a CH group reported so far. The complex described here is the first example of a cyclic complex stabilized by two improper CH⋅⋅⋅O hydrogen bonds. The conclusions drawn from the solution and solid‐state data were confirmed by ab initio calculations.