Abstract

The caesium phosphates Cs₃(H_1.5PO₄)₂(H₂O)₂ and Cs₃(H_1.5PO₄)₂ were obtained from aqueous solutions, and Cs₄P₂O₇(H₂O)₄ and CsPO₃ from solid state reactions, respectively. Cs₃(H_1.5PO₄)₂, Cs₄P₂O₇(H₂O)₄, and CsPO₃ were fully structurally characterized for the first time on basis of single-crystal X-ray diffraction data recorded at − 173 °C. Monoclinic Cs₃(H_1.5PO₄)₂ (Z = 2, C2/m) represents a new structure type and comprises hydrogen phosphate groups involved in the formation of a strong non-symmetrical hydrogen bond (accompanied by a disordered H atom over a twofold rotation axis) and a very strong symmetric hydrogen bond (with the H atom situated on an inversion centre) with symmetry-related neighbouring anions. Triclinic Cs₄P₂O₇(H₂O)₄ (Z = 2, P\(\bar{1}\)) crystallizes also in a new structure type and is represented by a diphosphate group with a P–O–P bridging angle of 128.5°. Although H atoms of the water molecules were not modelled, O···O distances point to hydrogen bonds of medium strengths in the crystal structure. CsPO₃ is monoclinic (Z = 4, P2₁/n) and belongs to the family of catena-polyphosphates (MPO₃)_n with a repetition period of 2. It is isotypic with the room-temperature modification of RbPO₃. The crystal structure of Cs₃(H_1.5PO₄)₂(H₂O)₂ was re-evaluated on the basis of single-crystal X-ray diffraction data at − 173 °C, revealing that two adjacent hydrogen phosphate anions are connected by a very strong and non-symmetrical hydrogen bond, in contrast to the previously described symmetrical bonding situation derived from room temperature X-ray diffraction data. In the four title crystal structures, coordination numbers of the caesium cations range from 7 to 12.

Graphic abstract

中文翻译：

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磷酸铯Cs 3（H 1.5 PO 4）2（H 2 O）2，Cs 3（H 1.5 PO 4）2，Cs 4 P 2 O 7（H 2 O）4和CsPO 3

摘要

从水溶液中获得磷酸铯Cs ₃（H _1.5 PO ₄）₂（H ₂ O）₂和Cs ₃（H _1.5 PO ₄）₂，以及Cs ₄ P ₂ O ₇（H ₂ O）₄和CsPO ₃分别来自固态反应。Cs ₃（H _1.5 PO ₄）₂，Cs ₄ P ₂ O ₇（H ₂ O）₄，和CsPO ₃首次在-173 °C下记录的单晶X射线衍射数据基础上进行了完整的结构表征。单斜Cs ₃（H _1.5 PO ₄）₂（Z  = 2，C 2 / m）代表一种新的结构类型，包含磷酸氢基团，参与形成一个强的非对称氢键（伴随有一个杂乱的H原子）旋转轴的两倍）和非常强的对称氢键（H原子位于反转中心）与对称相关的相邻阴离子。三斜Cs ₄ P ₂ O ₇（H ₂O）₄（Z  = 2，P \（\ bar {1} \））也会以新的结构类型结晶，并以桥联角为128.5°的二磷酸酯基团表示。尽管没有对水分子的H原子进行建模，但O···O距离指向晶体结构中强度中等的氢键。CSPO ₃是单斜晶系（ž  = 4，P 2 ₁ / Ñ）和属于家庭的系列-polyphosphates（中号PO ₃）_ñ具有2的重复周期是同种型与RbPO的室温修改₃。根据在-173°C下的单晶X射线衍射数据，对Cs ₃（H _1.5 PO ₄）₂（H ₂ O）₂的晶体结构进行了重新评估，结果表明连接了两个相邻的磷酸氢根阴离子与先前描述的从室温X射线衍射数据得出的对称键合情况相反，它具有非常强且不对称的氢键。在四个标题晶体结构中，铯阳离子的配位数为7至12。

图形摘要