Microwave Studies of the Internal Motion and the Structure of Methyl Amine

This is the final report of a series of papers from this laboratory on the internal motion and the structure of methyl amine. Most of the observed lines including J =1←0, K =0←0 lines were analyzed in the frequency range between 4 and 50 kMc/sec. The barrier height of internal rotation has been determined to be 691.1 cm -1 as well as the molecular structure, d CN =1.474 A, \(∠\)HNC=112°10', \(∠\)HNH=105°50', \(∠\)HCH=109°30' and the angle between CN and methyl axis=3°30' on the assumption that d CH =1.093 A and d NH =1.014 A. These results were compared with the barrier height and the structure of other CH 3 MH n type molecules, methyl alcohol and methyl mercaptan. The inversion doubling of the observed lines was also analyzed satisfactorily. The quadrupole coupling constant of N 14 along the charge symmetry axis has been obtained as -3.6±0.3 Mc/sec, with the direction of the axis, 90°±8, from the methyl axis.