Contributo allo studio sulle correlazioni fra struttura e proprietà di composti di interesse biologico. Nota I. Spettri Raman e u.r. di acetamide CH3CONH2 e del suo emicloridrato (CH3CONH2)2·HCl.

Bertoluzza, Alessandro ; Fagnano, Concezio ; Morelli, Maria Antonietta ; Tosi, Raffaella

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 58 (1975) no. 6, pp. 919-928

Résumé

I.r. and Raman spectra of acetamide CH3CONH2 and its emicloridrate (CH3CONH2)2·HCl are reported and discussed. I.r. spectra of (CH3CONH2)2·HCl shows a large and strong absorption about 850 cm-1, which is absent in the i.r. spectrum of CH3CONH2 and in the Raman spectra of CH3CONH2 and (CH3CONH2)2·HCl. Such a band can be attributed to an antisymmetric stretching vibration of (O--H--O)+ strong symmetric hydrogen bond between the carbonyl groups $\rangle C = O- -H^{+}- -O = C\langle$ of the (CH3CONH2)2·H+ ion, vibration which is allowed in i.r. but not in Raman. Such a hypothesis agrees with a partial X-ray study of literature on (CH3CONH2)2·HCl in which is suggested a strong and symmetric hydrogen bonding $\rangle C = O- -H^{+}- -O = C\langle$ with $O \cdots O$ bond length of 2,4 Å. It agrees also with the behaviour of $\delta OH$ deformation vibration and with that of symmetric stretching $\nu O--H--O$ vibration. Tentatively, an attribution of the i.r. and Raman spectra of (CH3CONH2)2·HCl is given in relation to that of CH3CONH2, considering the symmetry of the Ci, point group for the (CH3CONH2)2·H+ ion and the coupling of the vibrations through the (O--H--O)+ strong hydrogen bond.