These amides (C=O in place of CH(2)) too were found to undertake internal motions amenable to NMR observation, i.e., phenyl, tert-butyl, and N-CO rotations: the corresponding barriers were also measured. Ab initio computations indicate that H-bonding makes all these molecules adopt six-membered cyclic conformations, a conclusion which agrees well with the X-ray crystal structure determined for the amide
通过动态NMR光谱法,在典型的
氨基醇的两种非对映异构形式[二甲基
氨基-2,4,4-三甲基-甲基]中,通过动态NMR光谱法确定了三种内部运动的障碍(即,苯基和叔丁基旋转以及N转化)
3-苯基-3-戊醇,Me(2)NCH(2)CHMeC(OH)PhBu(t)]。通过与通过单晶X射线衍射确定的相应酰胺前体的那些连接来指定这两个结构。这些酰胺(C = O代替CH(2))也被发现进行了适合NMR观察的内部运动,即,苯基,叔丁基和N-CO旋转:还测量了相应的势垒。从头算计算表明,H键使所有这些分子均采用六元环状构象,这一结论与为酰胺前体确定的X射线晶体结构非常吻合。