The Flexibility of P2O7 Dimers in Soft Structures: M2CdP2O7 (M = Rb, Cs)

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• 作者：Xiaoyu Dong ; Yunjing Shi ; Mingjie Zhang ; Zhaohui Chen ; Qun Jing ; Yun Yang ; Shilie Pan ; Zhihua Yang and Hongyi Li
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：2016
• 期：17
• 页码：2704-2708
• 全文大小：1046K
• ISSN：1099-0682c

文摘

Two new congruent-melting alkali metal diphosphates, Rb₂CdP₂O₇ and Cs₂CdP₂O₇, were synthesized by conventional solid-state reactions. Single-crystal X-ray structural analyses showed that M₂CdP₂O₇ (M = Rb, Cs) feature two-dimensional [CdP₂O₇]^2– layers that are composed of CdO₅ pyramids and P₂O₇ dimers. The Rb⁺ and Cs⁺ cations ions fill the interlayers. The flexible P₂O₇ dimers could be bent and distorted if the Cs⁺ ion was substituted by the Rb⁺ ion, which led to crystallization of the Rb₂CdP₂O₇ compound in the lower symmetry monoclinic space group P2₁/c (No. 14) and crystallization of the Cs₂CdP₂O₇ compound in the high-symmetry orthorhombic space group Pnma (No. 53). Thermal analyses showed that the two compounds melt congruently and that the melting point of Rb₂CdP₂O₇ compound is lower than that of the Cs₂CdP₂O₇ compound owing to distortion of the P₂O₇ dimers. IR spectroscopy and UV/Vis–near-IR diffuse reflectance spectroscopy were performed on the reported compounds.