高度对称的氟代锗酸盐超分子化合物(NH_4)_2GeF_6·H_2O的溶剂热合成及其晶体结构

Solvothermal Synthesis and Crystal Structure of a High Symmetric Supermolecular Fluorogermanate (NH_4)_2GeF_6·H_2O

化合物 (NH4) 2 GeF6·H2 O由GeO2 ,NH4VO3 和HF在吡啶 -水体系中低温溶剂热条件下合成 ,并用IR、元素分析、TG DTA和X射线单晶衍射进行了表征 .化合物属立方晶系 ,空间群为Fm3m ,a =0 9118(2 )nm ,β =90° ,V =0 75 80 (3)nm3 ,Z =1,Dc=2 0 2 1g/cm3 ,F(0 0 0 ) =4 32 ,R1=0 0 6 12 ,wR2 =0 15 10 .晶体结构中包含 4个GeF6,4个H2 O和 8个孤立的NH+ 4 离子 .其中晶格水的引入导致了GeF2 -6八面体为Oh 对称性 ;进而GeF6和H2 O通过强烈的F…H—O氢键链接成 3 D具有 0 6 5 5 9nm× 0 6 5 5 9nm× 0 6 5 5 9nm空腔的栅格状骨架的超分子 (NH4) 2 GeF6·H2 O化合物 .NH+ 4 位于栅格的中心 ,以静电引力与GeF2 -6作用 ,进一步稳定了 3D超分子网络 .

NH 4) 2GeF 6·H 2O is obtained as light green single crystal from the low temperature solvothermal reaction of GeO 2, NH 4VO 3 and HF in pyridine water and characterized by the IR, elemental analysis, TG DTA and single crystal X ray diffraction. It crystallizes into cubical system, space group Fm3m, a =0 9118(2) nm, β = 90°, V =0 7580(3) nm 3, Z =1, D c=2 021 g/cm 3, F (000)=432, R 1=0 0612, wR 2=0 1510 for 357 reflections. The structure of the title compound consists of four GeF 2- 6 units, four crystal H 2O and eight NH + 4 cations. It is interesting that there exit GeF 2- 6 octahedra with high O h symmetry. Moreover, the GeF 2- 6 and H 2O connected 3 D grid shaped network through F...H-O hydrogen bonds. NH + 4 cations locate in the center of the grids and the electrostatic interactions between NH + 4 and GeF 2- 6 further stabilize the supramolecular network.