15N, 13C and 1H nuclear magnetic shielding and spin–spin coupling in gaseous 15N-enriched methylamine

New measurements of 15N, 13C and 1H nuclear magnetic resonance (NMR) spectral parameters have been performed for 15N-enriched methylamine (CH3 15NH2) in the gas phase. The solute compound was observed at low constant pressure (approx. 50 Torr) and the temperature of 300 K, while sulfur hexafluoride (SF6) and xenon (Xe) were used as the gaseous solvents. It was found that the 15N and 13C chemical shifts of CH3 15NH2 were linearly dependent on the solvent density and the appropriate shielding parameters for an isolated methylamine molecule were obtained, together with the coefficients responsible for the solute–solvent molecular interactions. In contrast the 1H chemical shifts and spin–spin coupling constants of CH3 15NH2 were found to be independent of density within experimental error. For the first time, the present measurements reveal the majority of NMR spectral parameters of methylamine free from intermolecular effects. q 2004 Elsevier B.V. All rights reserved.