$\text{}^{1}$H NMR Study of Molecular Dynamics of 4-apyH Cation under High Hydrostatic Pressure

Polycrystalline [4-NH$\text{}_{2}$C$\text{}_{5}$H$\text{}_{4}$NH] SbCl$\text{}_{4}$ and [4-NH$\text{}_{2}$C$\text{}_{5}$H$\text{}_{4}$NH] SbCl$\text{}_{6}$ have been investigated by proton NMR methods between 120 K and 370 K under hydrostatic pressure of 0.1 and 520 MPa. Reduction in the dipolar second moment is interpreted in terms of cation reorientation. Activation energies characterizing the motion increase with increasing pressure.