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Rotational isomerism of the tetraethylammonium cation in solution and in the solid state
Author(s) -
Naudin C.,
Bonhomme F.,
Bruneel J. L.,
Ducasse L.,
Grondin J.,
Lassègues J. C.,
Servant L.
Publication year - 2000
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/1097-4555(200011)31:11<979::aid-jrs629>3.0.co;2-y
Subject(s) - conformational isomerism , chemistry , raman spectroscopy , tetraethylammonium , ion , crystallography , solid state , aqueous solution , gauche effect , stereochemistry , molecule , organic chemistry , potassium , physics , optics , medicine , surgery
The tetraethylammonium ion Et 4 N + is shown to present rotational isomerism in aqueous or organic solutions between an all‐ trans conformation ( tt.tt or Greek cross) and a trans–gauche one ( tg.tg or Nordic cross). The Raman spectra of the two rotamers are distinct and their temperature dependence indicates that ( tt.tt ) is more stable than ( tg.tg ) by about 4.1 kJ mol −1 , i.e. by a value typical of two trans–gauche rotations. In some investigated solid salts at room temperature, the cation adopts one of these two conformations depending on the crystal structure and local packing effects induced by the anion. However, some other derivatives with bulky anions such as (Et 4 N) 2 CdBr 4 and Et 4 N(CF 3 SO 2 ) 2 N exhibit much more complicated conformational situations for the cation as a function of temperature. Copyright © 2000 John Wiley & Sons, Ltd.