PREPARATION, SPECTROSCOPIC PROPERTIES, AND CRYSTAL-STRUCTURES OF TE6(ASF6)4.2ASF3 AND TE6(ASF6)4.2SO2 - NEW TRIGONAL-PRISMATIC CLUSTER CATION, TE-6(4+)

The compounds Te6(AsF6)4-2AsF3 and Te6(AsF6)4-2SO2 have been prepared by the reaction of elemental tellurium with AsF5 in AsF3 or SO2 as solvent. Crystal structures of both compounds have been determined by three-dimensional X-ray counter measurements. Crystals of Te6(AsF6)4-2AsF3 are monoclinic with a = 14.832 (9) Å, b = 12.242 (8) Å, c - 15.301 (9) Å, and β = 96.59 (7)°. The structure has been refined in the space group C2/c to final agreement indices R1 = 0.082 (R2 = 0.099) for 1720 observed (I > 3σ(I)) data and R1 = 0.096 (R2 = 0.109) for all 2114 independent reflections. Crystals of Te6(AsF6)4-2SO2 are triclinic with a = 9.962 (3) Å, b = 10.681 (4) Å, c = 16.599 (4) Å, α = 107.69 (7)°, β = 92.40 (7)°, and γ = 120.10 (7)°. The structure of this compound has been refined in the space group PĪ to a final agreement index R1 of 0.093 for 1829 reflections with I > 3σ(I) and a weighted index R2 of 0.087 for 2708 independent reflections. Both compounds contain the novel trigonal-prismatic Te64+ species and consist of Te64+ and AsF6- ions and either AsF3 or SO2. The cation in the SO2 adduct is quite regular, within experimental error, but in the AsF3 adduct it is slightly distorted. The Te-Te bond distances in the triangular faces range from 2.662 to 2.694 Å, while those between the faces are considerably longer, ranging from 3.062 to 3.148 Å. Electronic spectroscopic studies are also reported on the Te64+ cation and these have shown that the species, which was previously identified as “Tenn+” in highly acidic media, is actually the Te64+ cation. © 1979, American Chemical Society. All rights reserved.