Chow Alyssa S, Zhong Xinyue, Fabini Douglas H, Zeller Matthias, Oertel Catherine M
Department of Chemistry and Biochemistry, Oberlin College, 119 Woodland Street, Oberlin, Ohio 44074, United States.
Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
Inorg Chem. 2022 May 2;61(17):6530-6538. doi: 10.1021/acs.inorgchem.2c00351. Epub 2022 Apr 21.
Hybrid lead halides are a diverse family of compounds, of interest for their optoelectronic properties, that vary in the dimensionality and connectivity of their inorganic substructures. The great majority of these compounds are based on lead-centered octahedra, with few examples featuring inorganic architectures containing higher coordination numbers. Here, we report the synthesis and characterization of a pyridinium lead bromide phase that is based on seven-coordinate Pb(II) centers. Through edge- and face-sharing, the polyhedra form a corrugated, two-dimensional inorganic substructure. Electronic structure calculations were used to examine the band structure and the role of the stereoactive lone pair in the inherently asymmetric, seven-coordinate Pb(II) geometry. For reference, we have visualized the role of the lone pair in the binary halide PbBr, which also has a seven-coordinate inner ligand sphere. A comparison of the new structure with the limited number of existing hybrid lead halides with similar inorganic architectures highlights the templating role of the organic cation for these compounds. We also contribute characterization and discussion of isomorphic pyridinium lead chloride, which had been deposited in the Cambridge Structural Database but never, to our knowledge, addressed in the literature. The compounds were synthesized using solution conditions and structures determined with single-crystal X-ray diffraction. The materials were also characterized via powder X-ray diffraction, combustion elemental analysis, and diffuse reflectance UV-vis spectroscopy. While the structures reported here are centrosymmetric, the seven-coordinate, capped trigonal prismatic geometry that we have identified is a source of local asymmetry that could be used as a component in designing globally noncentrosymmetric structures.
混合卤化铅是一类多样的化合物，因其光电特性而备受关注，它们的无机子结构在维度和连接性上有所不同。这些化合物中的绝大多数基于以铅为中心的八面体，只有少数例子具有包含更高配位数的无机结构。在此，我们报道了一种基于七配位Pb(II)中心的吡啶溴化铅相的合成与表征。通过边共享和面共享，多面体形成了一个波纹状的二维无机子结构。利用电子结构计算来研究能带结构以及立体活性孤对电子在固有不对称的七配位Pb(II)几何结构中的作用。作为参考，我们可视化了孤对电子在二元卤化物PbBr中的作用，它也有一个七配位的内配体球。将新结构与数量有限的具有相似无机结构的现有混合卤化铅进行比较，突出了有机阳离子对这些化合物的模板作用。我们还对同构的吡啶氯化铅进行了表征和讨论，该化合物已存入剑桥结构数据库，但据我们所知，在文献中从未被提及。这些化合物是在溶液条件下合成的，并通过单晶X射线衍射确定其结构。这些材料还通过粉末X射线衍射、燃烧元素分析和漫反射紫外可见光谱进行了表征。虽然这里报道的结构是中心对称的，但我们所确定的七配位、盖帽三角棱柱几何结构是局部不对称的一个来源，可作为设计全局非中心对称结构的一个组成部分。
