Synthesis, crystal structure, and solid state phase transition of Te4[AsF6]2•SO2
Synthesis, crystal structure, and solid state phase transition of Te4[AsF6]2•SO2
复制标题
DOI：
10.1002/zaac.200300044
复制
发表时间：
2003-06-01
影响因子：
1.4
通讯作者：
Fölsing, H
中科院分区：
文献类型：
--
作者：
Beck, J;Steden, F;Fölsing, H
在液态SO_2中，碲与AsF_5氧化生成Te-4（2+）[AsF_6-]（2），它可以作为SO_2溶剂化物从溶液中结晶出来，形成深红色晶体。晶体对空气非常敏感，容易损失SO2，因此需要在SO2气氛下处理或冷却。在室温、153 K和98 K下测定了晶体结构。127 K以上Te-4[AsF 6]（2）（SO2）-S-。晶体为正交晶系（Pnma，a = 899.2（1），B = 978.79（6），c = 1871.61（1）pm，V = 1647.13（2）（.）10（6）pm（3）在297 K，Z = 4）。该结构由正方形平面的Te-4（2+）离子（Te-Te 266 pm）、八面体[AsF 6]（-）离子和SO2分子组成，SO2分子与Te-4环的O原子在正方形边缘的桥接位置配位。在室温下，两个晶体学上独立的[AsF 6]（-）离子之一显示旋转无序冷却到153 K时没有完全解决。在127 K下，Te-4[AsF_6]（2）（SO_2）-S_-。经历固态相转变为单斜结构（P112（1）/a，a = 866.17（8），B = 983.93（5），c = 1869.10（6）pm，γ = 96.36（2）度，V = 1554，2（.）10（6）pm（3），在98 K，Z = 4）。所有[AsF 6]（-）离子都以低温形式有序。尽管空间群之间存在直接的超群-子群关系，相变是一阶的晶格参数的不连续变化。相变伴随着晶体孪晶。这两种结构的主要区别在于Te-4（2+）离子与被吸附的SO2和[AsF 6]（-）分子中O和F原子的配位不同。
The oxidation of tellurium with AsF5 in liquid SO2 yields Te-4(2+)[AsF6-](2) which can be crystallized from the solution in form of dark red crystals as the SO2 solvate. The crystals are very sensitive against air and easily lose SO2, so handling under SO2 atmosphere or cooling is required. The crystal structure was determined at ambient temperature, at 153 K, and at 98 K. Above 127 K Te-4[AsF6](2)(SO2)-S-. crystallizes orthorhombic (Pnma, a = 899.2(1), b = 978.79(6), c = 1871.61(1) pm, V = 1647.13(2)(.)10(6) pm(3) at 297 K, Z = 4). The structure consists of square-planar Te-4(2+) ions (Te-Te 266 pm), octahedral [AsF6](-) ions and of SO2 molecules which coordinate the Te-4 rings with their O atoms in bridging positions over the edges of the square. At room temperature one of the two crystallographically independent [AsF6](-) ions shows rotational disorder which on cooling to 153 K is not completely resolved. At 127 K Te-4[AsF6](2)(SO2)-S-. undergoes a solid state phase transition into a monoclinic structure (P112(1)/a, a = 866.17(8), b = 983.93(5), c = 1869.10(6) pm, gamma = 96.36(2)degrees, V = 1554,2(2)(.)10(6) pm(3) at 98 K, Z = 4). All [AsF6](-) ions are ordered in the low temperature form. Despite a direct supergroup-subgroup relationship exists between the space groups, the phase transition is of first order with discontinuous changes in the lattice parameters. The phase transition is accompanied by crystal twinning. The main difference between the two structures lies in the different coordination of the Te-4(2+) ion by O and F atoms of neighbored SO2 and [AsF6](-) molecules.