Quadrupolar effects transferred from N-14 to Si-29 have been observed in the magic-angle spinning NMR spectra of the cyclic polysilazanes octamethylcyclotetrasilazane, [(CH3)(2)SiNH](4), and hexamethylcyclotrisilazane, [(CH3)(2)SiNH](3). For the latter compound, three silicon and six carbon chemical shifts were observed, and the residual dipole-quadrupole splitting was in good agreement with the value calculated from the molecular structure in the gas phase and the known nuclear quadrupole coupling constant. No solid-solid phase transition occurs for this compound. For octamethylcyclotetrasilazane, four silicon, four nitrogen, and eight carbon resonance Lines were observed, in agreement with the reported crystal structure in which two distinct conformers occur in the unit cell. A phase transition occurs at 64 degrees C to a structure which showed only one silicon, one nitrogen, and two carbon resonances. On cooling, the high-temperature phase transforms to a glassy crystalline form which reverts to the stable form with a minimum in the half-life of 1.7 h at 30 degrees C. The kinetics of the conversion were followed using C-13 NMR spectroscopy.