High-Field 17O MAS NMR Reveals 1J(17O-127I) with its Sign and the NMR Crystallography of the Scheelite Structures for NaIO4 and KIO4<

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• 作者：Hans J. Jakobsen ; Henrik Bilds酶e ; Michael Brorson ; Gang Wu ; Peter L. Gor鈥檏ov ; Zhehong Gan ; Ivan Hung
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：June 25, 2015
• 年：2015
• 卷：119
• 期：25
• 页码：14434-14442
• 全文大小：363K
• ISSN：1932-7455

文摘

High-field, ambient-temperature (AT) ¹⁷O MAS NMR spectra of the tetraoxoanion IO₄^{鈥?/sup> in NaIO₄ and KIO₄ exhibit unusual line-shape features for the central transition (CT), which so far have not been observed in any second-order broadened line shape for the CT of a quadrupolar nucleus. These features are caused by an unusually large isotropic 1J(17O-127I) spin coupling (鈭?00 Hz) and appear like 鈥渢eeth-on-a-saw鈥? This study reports interesting results obtained from optimized fitting of the spectra using our recently described XSTARS software. The results include determination of a positive sign for 1J(17O-127I) (= +500 Hz), an unusual observation in solid-state NMR. NMR crystallography shows a very precise correlation between extraordinary small changes for the 17O asymmetry parameter (畏_Q) and changes for a tetrahedral O鈥揑鈥揙 angle upon distortion from an ideal tetrahedron. Similarly, the spectral analysis shows that the NMR crystallography requires the principal axes V_zz(17O) and 未_zz(17O) of the PAS for these tensors are both almost along the I鈥揙 bond. All the experimental data are in excellent agreement with our ADF and CASTEP calculations.}