Infrared spectra and vibrational assignments of trans–CH3N–NH, CH3N–ND, CD3N–NH, and CD3N–ND

Based on infrared spectra (4000–200 cm−1) of the gas phase, condensed phase (77°K), and nitrogen matrices (20°K) vibrational assignments for trans-CH3N–NH, CH3N–ND, CD3N–NH, and CD3N–ND have been obtained. The assignments of the fifteen fundamentals of each molecule are well founded in experiment except for the provisional values for the torsional mode. For trans-CH3N–NH the fundamentals are: (a′) 3127, 2992, 2925, 1559, 1457, 1435, 1382, 1120, 920, and 557 cm−1, (a″) 2988, 1430, 1140, 844, and ∼ 170 cm−1. Normal coordinate calculations are presented in support of these assignments and as a basis for further analysis of the published infrared spectra of the parent molecule, trans-N2H2. It is shown that the spectra for N2H2, N2HD, and N2D2 can now be interpreted in a unified way.