X-ray crystallographic, spectroscopic and quantum chemical studies on ethyl 2-cyano-3-N,N-dimethyl amino acrylate

Structural and spectral characteristics of ethyl 2-cyano-3-N,N-dimethyl amino acrylate have been studied by methods of X-ray crystallography, infrared spectroscopy and quantum chemistry. The compound crystallizes in monoclinic space group P21/n with unit cell parameters a = 4.26(1) Å, b = 11.16(1) Å, c = 19.63(3) Å and β = 95.5(1)°. The X-ray based three-dimensional structure analysis has been carried out by direct methods and fully refined. Density functional theory calculations for potential energy curves, optimized geometries and vibrational spectra have been carried out using 6-31G and 6-31G** basis sets and B3LYP functionals. These suggest the possibility of existence of two structural isomers for the molecule—a more stable s-cis and a less stable s-trans isomer, having enthalpy difference of 2.85 kcal/mol. The optimized molecular geometry is in agreement with experimental geometry from X-ray analysis and suggests a preferential s-cis conformation for the molecule in the solid state. Based on experimental and theoretical studies, it may be concluded that the molecule has an almost planar conformation with the cyanide group also lying in the molecular plane; the deviation from planarity does not exceed 3°. The structure is stabilized by the presence of intra-molecular and inter-molecular interactions.