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首页> 外文期刊>Zeitschrift fur Anorganische und Allgemeine Chemie >III. KLaSiS4 and RbLaSiS4 - A structural comparison
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III. KLaSiS4 and RbLaSiS4 - A structural comparison

机译：III. KLaSiS4 和 RbLaSiS4 - 结构比较

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摘要

Pale yellow, platelet shaped, air- and water resistant single crystals of KLaSiS4 derived from the reaction of lanthanum (La) and sulfur (S) with silicon disulfide (SiS2) in a molar ratio of 2 : 3 : I with an excess of potassium chloride (KCl) as flux and source of potassium ions in evacuated silica ampoules at 850 degrees C within seven days. The analogous reaction utilizing a melt of rubidium chloride (RbCl) instead also leads to yellow comparable single crystals of RbLaSiS4. The potassium lanthanum thiosilicate crystallizes monoclinically with the space group P2(1)/m (a = 653.34(6), b = 657.23(6), c = 867.02(8) pm, beta = 107.496(9)degrees) and two formula units per unit cell, while the rubidium lanthanum thiosilicate has to be assigned orthorhombically with the space group Pnma (a = 1728.4(2), b = 667.23(6), c = 652.89(6) pm) and four formula units in its unit cell. In both compounds the La3+ cations are surrounded by 8+1 sulfide anions in the shape of tricapped trigonal prisms. The Rb+ cations in RbLaSiS4 show a coordination number of 9+2 relative to the S2- anions, which form pentacapped trigonal prisms about Rb+. This coordination number, however, is apparently too high for the K+ cations in KLaSiS4, so that they only exhibit a bicapped trigonal prismatic environment built up by eight S2- anions. The isolated thiosilicate tetrahedra SiS4(4-) of the rubidium compound are surrounded by La3+ both edge- and face-capping, but terminal as well as edge- and face-spanning by Rb+. In the potassium compound there is no change for the La3+ environment about the SiS4(4-) tetrahedra, but the K+ cations are only able to attach terminal and via edges. The whole structure is built up by anionic (2)(infinity){LaSiS4}(-) layers that are separated by the alkali metal cations. in direct comparison the two thiosilicate structures can be regarded as stacking variants.
机译：KLa[SiS4]的淡黄色、片状、耐空气和防水单晶，由镧（La）和硫（S）与二硫化硅（SiS2）以摩尔比为2：3：I反应而得，以过量的氯化钾（KCl）为助熔剂，在850°C的真空二氧化硅安瓿中产生钾离子源，7天内。相反，利用氯化铷（RbCl）熔体的类似反应也导致了RbLa[SiS4]的黄色可比单晶。硫硅酸镧钾单斜结晶，空间群P2（1）/m（a = 653.34（6），b = 657.23（6），c = 867.02（8） pm，β = 107.496（9）度）和每个晶胞两个公式单位，而硫硅酸铷镧必须与空间群Ponma（a = 1728.4（2），b = 667.23（6），c = 652.89（6） pm）及其晶胞中的四个公式单元进行正交分配。在这两种化合物中，La3+ 阳离子被 8+1 硫化物阴离子包围，呈三棱柱状。RbLa[SiS4]中的Rb+阳离子相对于S2-阴离子显示出9+2的配位数，它们围绕Rb+形成五角形三棱柱。然而，对于KLa[SiS4]中的K+阳离子来说，这个配位数显然太高了，因此它们只表现出由八个S2-阴离子构建的双端三角棱柱环境。铷化合物的分离硫硅酸盐四面体 [SiS4]（4-） 被 La3+ 包围，边缘和面盖，但末端以及边缘和面跨越被 Rb+ 包围。在钾化合物中，La3+ 环境对 [SiS4]（4-） 四面体没有变化，但 K+ 阳离子只能连接末端和通过边缘。整个结构由阴离子 （2）（无穷大）{La[SiS4]}（-） 层构成，这些层被碱金属阳离子隔开。在直接比较中，两种硫硅酸盐结构可以被视为堆叠变体。

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