Smrcok Lubomír, Cerný Radovan, Boca Miroslav, Macková Iveta, Kubíková Blanka
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava, Slovak Republic.
Acta Crystallogr C. 2010 Feb;66(Pt 2):i16-8. doi: 10.1107/S0108270109055140. Epub 2010 Jan 8.
The crystal structure of tripotassium octafluoridotantalate, K(3)TaF(8), determined from laboratory powder diffraction data by the simulated annealing method and refined by total energy minimization in the solid state, is built from discrete potassium cations, fluoride anions and monocapped trigonal-prismatic TaF(7) ions. All six atoms in the asymmetric unit are in special positions of the P6(3)mc space group: the Ta and one F atom in the 2b (3m) sites, the K and two F atoms in the 6c (m) sites, and one F atom in the 2a (3m) site. The structure consists of face-sharing K(6) octahedra with a fluoride anion at the center of each octahedron, forming chains of composition FK(3) running along [001] with isolated TaF(7) trigonal prisms in between. The structure of the title compound is different from the reported structure of Na(3)TaF(8) and represents a new structure type.
通过模拟退火方法从实验室粉末衍射数据确定并经固态总能量最小化精修的八氟钽酸钾（K₃TaF₈）的晶体结构，是由离散的钾阳离子、氟阴离子和单帽三角棱柱形的[TaF₇]²⁻离子构成。不对称单元中的所有六个原子都处于P6₃mc空间群的特殊位置：Ta和一个F原子位于2b（3m）位置，K和两个F原子位于6c（m）位置，一个F原子位于2a（3m）位置。该结构由共用面的K₆八面体组成，每个八面体中心有一个氟阴离子，形成沿[001]方向的[FK₃]²⁺链，链间有孤立的[TaF₇]²⁻三角棱柱。标题化合物的结构与已报道的Na₃TaF₈结构不同，代表一种新的结构类型。
