31P MAS-NMR of Crystalline Phosphorous Sulfides. Correlation of 31p Chemical Shielding Tensors with Local Environments
CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
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31P MAS NMR is used to characterize local phosphorus environments in -P4S3, P4S7, P4S9, and P4S10. MAS-NMR spectra of P4S3 enable a chemical shift discrimination of the apical P atoms belonging to the two crystallographically distinct molecules in the unit cell. No line narrowing is observed for the basal P-atoms, indicating reorientation of the molecules about their C3 axes, as previously suggested from neutron diffraction data. MAS-NMR spectra of P4S7 show distinct resonances for all four crystallographically inequivalent P atoms within the molecular P4S7 units. Since, due to these site inequivalencies, spin- spin couplings are observable contrary to liquid state NMR, chemical shift assignments to P-P bonded units and S PS32 groups are possible. The spectra of P4S9 and P4S10 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.
- Inorganic Chemistry