Infrared and Raman Spectra of Substituted Hydrazines. I. Methylhydrazine

The infrared gas phase spectra of methylhydrazine (NH2NHCH3), methylhydrazine-d3 (ND2NDCH3), and methylhydrazine-d6(ND2NDCD3), have been measured from 33 to 4000 cm−1. The infrared and Raman spectra of the corresponding compounds in the liquid state have also been recorded. A complete vibrational analysis based on band intensity, position, and isotopic shift is presented. A series of sharp Q branches in the far-infrared region facilitated calculations of the torsional barriers. By assuming that a symmetrical threefold cosine potential governs both rotors in NH2NHCH3 we calculate barriers of 3.67 and 3.72 kcal/mole for the methyl and amino torsions, respectively. The intensity of the 3182-cm−1 line of NH2NHCH3 has been studied as a function of temperature. The ΔH° for H-bond formation is found to be − 418 cal/mole. Thermodynamic functions for NH2NHCH3 have been calculated for the temperature range 200°–3000°K on the basis of a rigid rotator, harmonic oscillator model.