Vibrational study of methylamine dimer and hydrated methylamine complexes in solid neon supported by ab initio calculations

Abstract

For the first time the investigation of water molecule complexed with methylamine (CH3NH2) in solid neon was performed from 80 to 6000 cm−1 using Fourier transform infrared spectroscopy. From concentration effects and with the help of theoretical results we have identify several vibrational transitions for CH3NH2 dimer, CH3NH2-H2O, and CH3NH2-(H2O)2 complexes. For the CH3NH2-H2O complex, where the two submolecules interacting through hydrogen bonding, the infrared (IR) spectral changes (frequencies as well as intensities) indicate that the water playing the role of the proton donor, in agreement with the previous theoretical works. Theoretical calculations at the second-order Møller-Plesset level have been performed to obtain their equilibrium geometries and vibrational spectra at the harmonic level and comparison with experimental data allows us to give structures of observed complexes.