INFRARED AND RAMAN SPECTRA OF SUBSTITUTED HYDRAZINES .2. UNSYMMETRICAL DIMETHYL HYDRAZINE

The infrared spectra of unsymmetrical dimethyl hydrazine, H 2NN(CH3)2, and unsymmetrical dimethyl hydrazine-d2, D2NN(CH3)2, have been recorded in both the liquid and gaseous states from 33 to 4000 cm-1. In addition the infrared spectrum of solid H2NN(CH3) 2 has been measured from 33 to 4000 cm-1 and that of D2NN(CH3)2 from 33 to 400 cm-1. The Raman spectra of the liquid dimethyl hydrazines have been obtained from 200 to 4000 cm-1 and depolarization measurements were made. The spectra were interpreted on the basis of C1 symmetry, and all 30 vibrations have been assigned on the basis of the band positions, relative intensities, and isotopic shift. The methyl torsional fundamentals were observed, and the barrier hindering the rotation of the CH3 group was calculated to be 4.69 kcal/mole. A symmetrical threefold cosine-based potential function has been employed in calculating a barrier height of 3.2 kcal/mole for the amino torsional vibration. Thermodynamic functions have been calculated for the temperature range 200-3000°K on the basis of a rigid-rotator harmonic-oscillator model for all vibrations except those involving the internal rotation of the amino and methyl groups, for which appropriate corrections have been made.