Martineau Charlotte, Fayon Franck, Legein Christophe, Buzaré Jean-Yves, Body Monique, Massiot Dominique, Goutenoire François
Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Le Mans Cedex 9, France.
Dalton Trans. 2008 Nov 28(44):6150-8. doi: 10.1039/b810863c. Epub 2008 Sep 17.
The results from one-dimensional multinuclear (19F, 207Pb and 67Zn) magic-angle spinning nuclear magnetic resonance experiments combined with the use of the ISODISPLACE program allow for the space group determination of beta-Pb2ZnF6 (no. 138 P4(2)/ncm). The structure was refined from X-ray powder diffraction data (a = 5.633 (1) A and c = 16.247 (1) A, Z = 4). beta-Pb2ZnF6 has one six-fold coordinated Zn, one eleven-fold coordinated Pb and five F non-equivalent crystallographic sites and is built from alternated layers parallel to the (a, b) plane; tilted ZnF4(2-) layers of corner sharing ZnF6(4-) octahedra and FPb+ layers of edge sharing FPb4(7+) tetrahedra. The structure of beta-Pb2ZnF6 was then optimized using the ab initio code WIEN2k and the calculated 67Zn EFG is in agreement with the NMR results. 19F-19F proximities and 19F-207Pb connectivities were evidenced using through-space and through-bond NMR correlation experiments, respectively, and support the proposed structure. 19F-207Pb J-coupling was also used to select fluorine resonances depending on the number of neighbouring lead ions, leading to an unambiguous assignment of the different 19F resonances.
一维多核（¹⁹F、²⁰⁷Pb和⁶⁷Zn）魔角旋转核磁共振实验结果与ISODISPLACE程序相结合，可确定β-Pb₂ZnF₆（编号138，P4(2)/ncm）的空间群。该结构由X射线粉末衍射数据（a = 5.633(1) Å，c = 16.247(1) Å，Z = 4）精修得到。β-Pb₂ZnF₆有一个六配位的Zn、一个十一配位的Pb和五个不等价的F晶体学位置，由平行于(a, b)平面的交替层构成；由角共享ZnF₆(4-)八面体的倾斜ZnF₄(2-)层和边共享FPb₄(7+)四面体的FPb⁺层组成。然后使用从头算代码WIEN2k对β-Pb₂ZnF₆的结构进行了优化，计算得到的⁶⁷Zn电场梯度与核磁共振结果一致。分别通过空间和键间核磁共振相关实验证实了¹⁹F-¹⁹F邻近性和¹⁹F-²⁰⁷Pb连接性，并支持了所提出的结构。¹⁹F-²⁰⁷Pb J耦合也用于根据相邻铅离子的数量选择氟共振，从而明确了不同¹⁹F共振的归属。
