EFFECTS OF MOLECULAR ASSOCIATION ON THE NMR SHIELDING CONSTANTS IN METHYLAMINE

The N-15, C-13 and H-1 NMR chemical shifts were measured for methylami ne in the gaseous and liquid phase. The gas to liquid shifts reveal th e deshielding effects for all investigated nuclei. It is shown that th e hydrogen bonding is responsible for the largest changes, which,are o bserved for the nitrogen and amino hydrogen atoms as well. The CHF-GIA O calculations indicate that the cyclic trimer of methylamine exhibits the shielding changes, which are in qualitative agreement with the ga s to liquid shifts.