31P MAS-NMR of Crystalline Phosphorous Sulfides. Correlation of 31p Chemical Shielding Tensors with Local Environments [report]

Hellmut Eckert, Cheryl S. Liang, Galen D. Stucky
1988 unpublished
3 '1 p MAS NMR is used to characterize local phosphorus environments in -P 4 S 3 , P 4 S 7 , P 4 S 9 , and P 4 SI 0 . MAS-NMR spectra of P 4 S 3 enable a chemical shift discrimination of the apical P atoms belonging to the two crystal log raph ically distinct molecules in the unit cell. No line narrowing is observed for the basal P-atoms, indicating reorientation of the molecules about their 03 axes, as previously suggested from neutron diffraction data. MAS-NMR spectra of P 4 S 7 show distinct
more » ... resonances for all four cr'ystal log raph ically inequivalent P atoms within the molecular P 4 S 7 units. Since, due to these site inequivalencies, spin-spin couplings are observable (contrary to liquid state N.MIR), chemical shift assignments to P-P bonded units and S=PS 3 / 2 groups are possible. 5 The spectra of P 4 S 9 and P 4 S 1 o disagree with earlier literature reports, and are subject to a reinterpretation in the present study. Analyses of spinning sideband intensities yield the principal shielding tensor components, which are correlated with crystallographic data., S=PS 3 / 2 and PS 3 / 2 units are easily distinguished by opposite signs of the chemical shift anisotropies. * DII PI eoo r e1 8-~ J.-e)Dt.Y-t~,
doi:10.21236/ada196557 fatcat:pwllp2fvafcipaiwnvoelfthre