Wideline NMR studies of ammonia intercalation complexes. II. TaS2(ND3) and TiS2 (ND3)

Abstract

The 2D NMR of ND3 molecules in the intercalation complexes TaS2(ND3) and TiS2(ND3) has been studied at temperatures from 5–300 K by wideline techniques. The magnitude and temperature dependence of the observed electric quadrupolar coupling constant (e2qQ/h)eff provides information about the configuration of the intercalated ND3 molecules and their dynamics. The similarity of (e2qQ/h)eff to previously reported values for solid ND3 suggests that intercalation entails only small changes in molecular geometry or electronic configuration. The molecules exhibit several types of motion, including spinning about their threefold (C3) symmetry axis and a complex reorientation of that axis. The rates of these motions are reduced as the temperature is lowered, with reorientation falling to ∼106 s−1 near 140 K. C3 spinning persists at rates greater than 106 s−1 even at temperatures of 5 K. The quadrupole interaction does not vanish at high temperatures, ∼300 K, showing that reorientation of the C3 axis is not isotropic and the form of motion is deduced from the high temperature value of the coupling constant. A central component of the spectrum is observed at low temperatures and attributed to ND3 molecules residing near molecular vacancies in the layers. The present results are compared in detail with 1H observations in the ND3 analogues.