The crystal structure of tellurium tetraiodide TeL was determined from three-dimensional X-ray diffractometer data and was refined by full-matrix least-squares methods to an R index of 5.1%. The crystals are orthorhombic, space group Pnma, with a= 13.635 (5), b= 16.798 (5), c= 14.624 (5)/~, Z= 16TeI4. The structure is built of tetrameric (TeI4)4 molecules which are not isomorphous with the (TeCl4)4 molecular structure, but form a novel binary X4Y16 structure type composed of edge-sharing TeI6 octahedra. Mean Te-I bond lengths are 2.769, 3.108 and 3.232 ,~ for bonds to terminal, doubly and triply bridging iodine atoms, respectively. Intermolecular I...I distances as short as 3.870, 3"893, 3.932 ,~ indicate weak bonding interactions between the Te4116 molecules. Within the series of the TeF4, TeCL and TeL crystal structures, a strong decrease of the stereochemical activity of the non-bonding electron pair on tellurium(IV) is observed.

Tellur(IV)‐jodid besitzt eine bei binären anorganischen Verbindungen im festen Zustand bisher nicht beobachtete Molekülstruktur: sie enthält tetramere Bausteine der Zusammensetzung Te4J16 (1), die ihrerseits aus TeJ6‐Oktaedern bestehen, die über ihre Kanten miteinander verknüpft sind.

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Abstract The trimeric chlorotellurate(IV) ion Te3Cl13- is obtained in benzene solution as a degradation product of cubane-like tetrameric tellurium(IV) chloride Te4Cl6 and can be isolated by crystallization in the form of salts with large cations. The crystal structure of the triphenyl-methyl salt (C6H5)3CTe3Cl13 (P21/c, a = 1109.5, b = 1644.4, c = 2043.9 pm, β = 114.50°) shows the Te3Cl13- ion to have approximate C3V symmetry; as a fragment of the Te4Cl16 cube it consists of three edge-sharing octahedra with a central triply bridging Cl. Bond distances Te-Cl (tripl.br.) 292.4-298.4, Te-Cl (doubl.br.) 270.6-286.3, Te-Cl (term.) 232.0-238.8 pm. The vibrational spectrum of Te3C13- is discussed.

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