Infrared spectra and structure of the cyano and methoxycarbonyl derivatives of 3,3-bis(dimethylamino)acrylonitrile: an ab initio force field treatment

The structure of 2-cyano-3,3-bis(dimethylamino)acrylonitrile and 2-methoxycarbonyl-3,3-bis(dimethylamino)acrylonitrile has been studied on the basis of both infrared spectra and ab initio force field calculations. The 3012-376 cm(-1) region bands have been assigned; a good agreement has been found between the theoretical and experimental spectroscopic characteristics. According to both infrared data and bond parameters, the C=C bond in the molecules studied is strongly polarized. The ground-state charge transfer between the electropositive and electronegative fragments of the molecules is more than 0.5 e(-), so the species studied have a dual character, both molecular and zwitterionic. (C) 1997 Elsevier Science B.V.