Study of molecular dynamics and phase transitions in trimethylammonium trichlorogermanate using 1H NMR and DSC measurements

(CH3)3NHGeCl3 is prepared, characterized and studied by 1H NMR and differential scanning calorimetry to understand the molecular dynamics and phase transitions. The proton spin lattice relaxation time (T1) is measured at 20.53 MHz in the temperature range 391–5.2 K employing a home‐made pulsed NMR spectrometer. The T1 results show that (CH3)3NHGeCl3 undergoes several phase transitions in the temperature range 391–50 K. Both T1 data and DSC thermograms support the occurrence of phase transitions at 272 K and around 323 K. T1 data are analyzed in three temperature regions using standard models. The T1 variations in the intermediate temperature region 272–100 K are attributed to the hindered reorientations of symmetric groups (CH3 and (CH3)3NH). A broad asymmetric T1 minimum in the temperature region 45–20 K is attributed to quantum rotational tunneling of the methyl groups. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)