NITROGEN INVERSION AND N-O BOND ROTATION PROCESSES IN DI-SUBSTITUTED AND TRI-SUBSTITUTED HYDROXYLAMINES - A DYNAMIC NMR-STUDY

The barriers to inversion in several acyclic di- and tri-substituted h ydroxylamines are determined by H-1 NMR band shape analysis. The barri ers range from 49.1 to 66.8 kJ mol(-1) and are discussed in terms of a conformational process which involves nitrogen inversion and rotation around the N-O bond. The N-benzyl group with an ortho hydroxy substit uent increases the nitrogen inversion barrier by 10 kJ mol(-1), which indicates the requirement of breaking of the intramolecular hydrogen b ond prior to inversion.