Low-Temperature Syntheses and Characterization of Novel Layered Tellurites, A2Mo3TeO12 (A = NH4, Cs), and “Zero-Dimensional” Tellurites, A4Mo6Te2O24·6H2O (A = Rb, K)

Hydrothermal synthetic investigations to prepare new A2Mo3TeO12 (A = NH4, Cs, Rb, K) compounds are described.
Novel noncentrosymmetric layered tellurites, (NH4)2Mo3TeO12 (1) and Cs2Mo3TeO12 (2), have been synthesized
by hydrothermal methods. Their structures contain two-dimensional hexagonal tungsten oxide related (Mo3TeO12)2-
anionic layers interleaved with NH4+/Cs+ ions. New “zero-dimensional” tellurites, Rb4Mo6Te2O24·6H2O (3) and
K4Mo6Te2O24·6H2O (4), containing discrete centrosymmetric (Mo6Te2O24)4- anionic aggregates and alkali metal
ions have been synthesized by simple refluxing of stoichiometric reactants in water. In this hexamolybdoditellurite
anion, the Mo6O24 flat hexagonal ring, formed from edge sharing of six MoO6 octahedra, is capped by tellurium
on both sides. The two types of anions have the same empirical formula. Cs2Mo3TeO12 (2) could be prepared
by a solid state reaction as well. All four new tellurites have been structurally characterized by single-crystal
X-ray diffraction studies. Pertinent crystal, data are as follows:  for 1, hexagonal space group P63, a = 7.332(2)
Å, c = 12.028(4) Å, Z = 2; for 2, hexagonal space group P63, a = 7.3956(10) Å, c = 12.186(2) Å, Z = 2; for
3, monoclinic space group P21/c, a = 10.0564(14) Å, b = 9.877(8) Å, c = 15.724(3) Å, β = 109.988(11)°, Z =
2; for 4, monoclinic space group P21/c, a = 9.878(3) Å, b = 9.724(4) Å, c = 15.301(3) Å, β = 108.57(2)°, Z =
2. Low-temperature syntheses, structure, and powder X-ray diffraction, spectroscopic, and thermal studies of
compounds 1−4 are described.

本文详细阐述了通过水热合成方法制备新型A2Mo3TeO12（A = NH4, Cs, Rb, K）类化合物的研究。文中介绍了两种新颖的非中心对称层状碲酸盐化合物（NH4）2Mo3TeO12（1）和Cs2Mo3TeO12（2）的合成过程，其结构包含二维的六方钨氧化物相关（Mo3TeO12）2-阴离子层，并交替排列NH4+/Cs+离子。此外，通过水溶液中化学计量反应的简单回流，成功合成了两种新的“零维”碲酸盐化合物，即Rb4Mo6Te2O24·6H2O（3）和K4Mo6Te2O24·6H2O（4），它们含有离散的具有中心对称性的（Mo6Te2O24）4-阴离子团簇和碱金属离子。在此六钼二碲酸盐阴离子中，由六个MoO6八面体边共享形成的Mo6O24平面六角环，两侧均被碲原子所封顶。这两种类型的阴离子具有相同的经验公式。Cs2Mo3TeO12（2）还可以通过固态反应制备。所有四种新合成的碲酸盐均通过单晶X射线衍射研究进行了结构表征。相关晶体数据如下：对于1，六方空间群P63，a = 7.332(2) Å，c = 12.028(4) Å，Z = 2；对于2，六方空间群P63，a = 7.3956(10) Å，c = 12.186(2) Å，Z = 2；对于3，单斜空间群P21/c，a = 10.0564(14) Å，b = 9.877(8) Å，c = 15.724(3) Å，β = 109.988(11)°，Z = 2；对于4，单斜空间群P21/c，a = 9.878(3) Å，b = 9.724(4) Å，c = 15.301(3) Å，β = 108.57(2)°，Z = 2。同时，对化合物1-4的低温合成、结构、粉末X射线衍射、光谱和热学性质进行了描述。