The crystal structure of formamide

Infrared spectrum of formamide in the solid phase

“…This claim is supported by the experimental identification of dimers in the crystalline [20] and amorphous [21] solid formamide and the absence of formamide monomer mass spectrometry signatures at higher temperatures [12]. Warming up the sample to 300 K we found that all formamide or the dimers / polymers had sublimed and left no residue on the substrate.…”

“…The crystal structure of solid formamide has been determined [20] The presence of such dimers was experimentally observed in the infrared spectra, using 0.5 cm -1 resolution, with the identification of the characteristic vibrations for formamide dimers occurring in the NH 2 and CO vibrational regions [21]. In the present work it was hard to distinguish these peaks in our spectra due to our limited 2 cm -1 resolution.…”

Unifying Features Relating to the 3D Structures of some Intercalates of Kaolinite

“…The carbonyl oxygen is only 2.1 ~ out of the plane of the hydroxyls, approximately 1 ]k less than that predicted from an impenetrable layer; the hydrogen atom involved in the hydrogen bond to the silicate oxygen is about 2.0 ~ from this oxygen layer, approximately 0.5 ]~ less than that predicted on van der Waals radii grounds. The other observations of Ledoux and White (1%6a,b) also can be rationalized: the monomerization of the formamide molecules is confirmed and the relatively weak N-H. 9 9 O bonds (3" 05 and 3-21 & compared with 2" 94 /~ in solid formamide) (Ladell and Post, 1954) were also found. Knowledge of the structure has solved the problem of whether these weak hydrogen bonds are to the clay sheets or to other formamide molecules.…”

Interpretation of Solid state 13C and 29Si Nuclear Magnetic Resonance Spectra of Kaolinite Intercalates

“…Some justification exists, however, for inferring such a relationship between the carbonyl ~3C resonance of dilute formamide in chloroform and that of the kaolinite: formamide intercalate. Obviously in pure formamide very significant amide-res-onance effects are present which are reflected in the differences in formamide bond lengths observed between the solid (Ladell and Post, 1954) and the dickite intercalate (Adams and Jefferson, 1976).…”