STRUCTURE AND DYNAMICS OF SOLID TRIS(TRIMETHYLSILYL)AMINE BY DEUTERIUM NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

Deuterium NMR spectra for solid [H-2(9)]tris(trimethylsilyl)amine were recorded at 77 K and in the region 114-353 K. At 77 K there is only fast rotation of the methyl groups. Between 122 and 171 K rotation of the trimethylsilyl groups and of the entire molecule (about its C3 axis) affect the deuterium N M R line shape. Above 180 K both motions are fast ( > 10(5) Hz). There is a phase transition at 227 +/- 2 K. Above 227 K the molecule undergoes a fast precessional motion of increasing effective amplitude until the melting point (343 K). The only dynamic model capable of explaining the spectra at temperatures above 180 K requires the three N-Si bonds to be coplanar.