An experimental and computational investigation of the structure and vibrations of dimethylethylenediamine, a model for poly(ethylenimine)

A combination of hybrid Hartree?Fock/density functional calculations and Raman and IR spectroscopy has been used to perform a vibrational analysis of N,N'-dimethylethylenediamine (DMEDA) and provide band assignments for the experimental spectroscopic data. The structures and vibrational frequencies of several low energy conformations of DMEDA were calculated. The lowest energy structure was found to be TGT with a single intramolecular hydrogen bond. The effect of intramolecular hydrogen bonding on the structures and vibrational frequencies was investigated. Liquid DMEDA is found to be predominantly a mixture of two conformations: TGT with one intramolecular hydrogen bond and TGT with no intramolecular hydrogen bonds