C-13 NMR-STUDY OF THE METAL-INSULATOR AND STRUCTURAL PHASE-TRANSITIONIN THE ORGANIC CONDUCTOR (FLUORANTHENYL)2PF6

C-13 NMR measurements on single crystals of (fluoranthenyl)2PF6 at var iable temperatures and for different orientations of the crystals with respect to the external field reveal strongly temperature-dependent K night-shift anisotropies. Hyperfine-interaction tensors for the differ ent carton sites of the fluoranthene molecule were determined and are compared with molecular-orbital-type calculations. The temperature dep endence of the paramagnetic spin susceptibility was determined through the metal-insulator transition. The spectra exhibit clearly a structu ral, as well as a metal-insulator, phase transition at and below 200 K . A detailed analysis of the temperature-dependent shift data leads to the determination of the temperature-dependent order parameter for bo th transitions.