Symmetry tree and group-subgroup relationships:
P4,lnmc
The '"C CPlMAS NMR spectra were recorded at a sample rotation speed of 3 kHr and a contact time of 1 ms. The measurements at higher temperatures (above SO C) were carried out by in a single pulse excitation (SPE) experiment. The B , field strength of the proton decoupler was varied between 41 and 83 kHz to confirm the line width decoupling strength relationship [11,12]. The best resolution in the "Si CP/MAS NMR spectra was obtained for the sample enriched to 95 Yo with the 'Li isotope. In order to confirm the quadrupolar splitting by "N (171, the 29Si CP/MAS NMR spectrum was additionally recorded at a field strength of 9.45 T (79.4 MHz). The 'LI MAS N M R spectra were recorded by using the SPE experiment. In order to avoid saturation, recycle delays of 30 s were used. All 'Li NMR spectra of the 95 % isotopically enriched compound were recorded by using thecross-polarization method with contact times of 5 to 10 ms. All measurements were performed by using dipolar ' H decoupling and carried out on a Bruker MSL 200 S spectrometer equipped with a B-VT 2000 temperature control unit. Air-tight Kel-F inserts which fit into 7 mm MAS rotors were used for the preparation of the samples. See ref.
[ S ] for the solid-state NMR data W.