The novel route for synthesis of tellurium tetrachloride, and redetermination of its structure at lower temperature by X-ray crystallography.

The reaction of iodine trichloride with tellurium in a sealed evacuated gla ss ampoule at 250 degrees C yields yellow-green, moisture sensitive crystal s of TeCl4. The crystal structure of TeCl4 has been determined in low tempe rature at 100 K from three-dimensional X-ray data collection. The compound crystallizes in space group C2/c of monoclinic system with unit cell dimens ions a = 16.846(3)Angstrom, b = 10.347(2)Angstrom, c = 15.051(3)Angstrom, b eta = 116.87(3)degrees, Z = 8, V = 2340.2(8)Angstrom(3), rho(c) = 3.059 g/c m(3), final R indices [I>2 sigma (I)] R = 0.0507, wR = 0.1304, and R indice s (all data) R = 0.0564, wR = 0.1341. The structure consists of tetramers, Te4Cl16, which have a cubane-like stru cture. The Te atoms occupy the half of the corners with T-d symmetry. Each Te atom has been attached to three terminal Cl atoms with an average distan ce of 2.325 Angstrom. The coordination of the Te atom is completed to a dis torted octahedron by three bridging chlorine atoms with much longer Te-Cl b ond lengths (average 2.915 Angstrom). In the polar limiting case the struct ure may be described, in a rough approximation, as an arrangement of TeCl3 ions with nearly C-3v symmetry and of Cl- ions. The structure data suggest possible concentration of the nonbonding Te electrons toward the center of the cubane skeleton.