Barrier to C-N rotation in selenoformamide: an ab initio study

Abstract

Ab initio calculations at HF/6-31G∗ and MP2/6-31∗ levels were performed on selenoformamide to obtain the C-N bond rotational energy barriers. The C-N rotational barrier in selenoformamide is 21.88 kcal/mol which is larger than the C-N bond rotation in formamide (15.79 kcal/mol) and in thioformamide (20.52 kcal/mol). C-N bond length decreases, bond strength increases and flow of charge from N to X increases in the order formamide < thioformamide < selenoformamide. It is found that the electronegativity of X cannot be taken as the driving force for the delocalization of electrons onto the π framework of the X-CH-NH2.