Abstract
The effort for determining NMR interaction tensors from orientation-dependent spectra of single crystals may be greatly reduced by exploiting symmetry relations between atoms of the observed nuclide in the unit cell, as is well documented in the literature. In this work, we determined both the full chemical shift (CS) tensor of Pb-207 and the unknown orientation of the rotation axis for the natural mineral phosgenite, Pb2Cl2CO3, from a single rotation pattern, i.e. spectra of crystal orientations from 0 to 180 degrees. In the tetragonal crystal structure of phosgenite, four symmetry-related, but magnetically inequivalent Pb-207 are generated by the WYCKOFF multiplicity. The mineral wulfenite, PbMoO4, also crystallises in a tetragonal space group, but the site multiplicity for Pb-207 generates only one magnetically inequivalent atom, thus not supplying sufficient experimental data to determine CS tensor and axis orientation from an arbitrary number of rotation patterns. One solution to this problem is to simultaneously acquire data of a known compound with high symmetry and WYCKOFF multiplicity (here: phosgenite), which supplies additional constraints making the solution of the target compound (here: wulfenite) possible. The Pb-207 CS tensors thus determined are characterised by the following eigenvalues in ppm: delta(PAS)(11) = (-2553 +/- 1) , delta(PAS)(22) = (-1929 +/- 1) , delta(PAS)(33) = (-1301 +/- 1) for phosgenite, and delta(PAS)(11) = (-2074 +/- 1) , delta(PAS)(22) = (-2074 +/- 1) , delta(PAS)(33)= (-1898 +/- 1) for wulfenite.
| Item Type: | Journal article |
|---|---|
| Faculties: | Chemistry and Pharmacy > Department of Chemistry |
| Subjects: | 500 Science > 540 Chemistry |
| ISSN: | 0926-2040 |
| Language: | English |
| Item ID: | 83295 |
| Date Deposited: | 15. Dec 2021 15:07 |
| Last Modified: | 15. Dec 2021 15:07 |
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