Dynamic properties of P4O6S and P4O7: P-31 spin-echo and P-31 MAS-NMR investigations

The rotational dynamics of P4O6S and P4O7 in the solid state were studied b y means of P-31 NMR spectra of spinning and static powder samples in the te mperature range of 153-295 K and 295-388 K, respectively. All spectra were simulated to confirm the type of the motion and to extract the time scales as a function of the temperature. Good agreement between experimental and t heoretical data was obtained on the basis of a three-site jump model. For P 4O6S, the activation energy and the pre-exponential factor derived from the lineshape simulations amount to 51(2) kJ/mol and 6(3).10(15) s(-1). For P4 O7, the spectral analysis yields an activation energy of 67(1) kJ/mol and a pre-exponential factor of 6(2).10(14) s(-1). The dynamic behavior was chec ked independently by lineshape analyses under both MAS and static condition s. Activation energies are consistent within the errors for the lineshape a nalyses. Additionally, we have analyzed spin-lattice relaxation measurement s, which show the correct trends for the activation energies. (C) 1999 Else vier Science B,V. All rights reserved.