XeF2·2CrF4 and XeF5+CrF5-: Syntheses, Crystal Structures, and Some Properties
摘要:
XeF2. 2CrF(4) was prepared by solvolysis of XeF2. CrF4 in anhydrous hydrogen fluoride (aHF) and subsequent decantation of the majority of dissolved XeF2 in aHF. Remaining XeF2 and a large excess of CrF4 form XeF2. 2CrF(4) after aHF is removed. Ruby-red single crystals were obtained either by healing the sample in a thermal gradient or by recrystallization in supercritical SF6. The compound crystallizes in the triclinic space group P (1) over bar with a = 855.1(3) pm, b = 922.1(3) pm, c = 1043.8(3) pm, alpha = 76.02(2)degrees, beta = 81.36(2)degrees, gamma 88.08(3)degrees, and Z = 4 at 293 K. The basic structural unit is formed by four independent Cr atoms, each octahedrally coordinated by six F atoms. Two fluorine ligands are provided by two different XeF2 molecules. The distorted octahedra are connected via common F atoms to form a three-dimensional network. XeF5+CrF5- was prepared from XeF6 and CrF4 at room temperature or by the reaction of XeF6 and CrF5 at 333 K. Red single crystals were grown from the solution of XeF5+CrF5- in aHF. The compound crystallizes in the orthorhombic space group Pbca with a = 1828.1(13) pm, b = 842.9(7) pm, c 1852.1(12) pm, and Z = 16 at 268 K. The main structural feature is formed by an infinite chain of distorted CrF6 octahedra joined via cis vertexes, while XeF5+ cations compensate the negative charge of each octahedron.