Tellurium tetrachloride structure

Tellurium nitride was first obtained by the reaction of TeBt4 with liquid ammonia more than 100 years ago. The empirical formula TeN was assigned to this yellow, highly insoluble and explosive substance. However, subsequent analytical data indicated the composition is Tc3N4 which, in contrast to 5.6a and 5.6b, would involve tetravalent tellurium. This conclusion is supported by the recent preparation and structural determination of Te6N8(TeCl4)4 from tellurium tetrachloride and tris(trimethylsilyl)amine (Eq. 5.5). The TceNs molecule (5.12), which is a dimer of Tc3N4, forms a rhombic dodecahedron in which the... 

TELLURIUM. TCAS 13494-80-91. Chemical element, symbol Te, at. no. 52. at. wL 127.60, periodic table group 6, mp 450°C, bp 690°C, density 6.24 g/cm3 (crystalline form at 25°C), 6.00 (amorphous farm at 25°C). Elemental tellurium has a hexagonal crystal structure with trigonal symmetry. Tellurium is a silver-white brittle semi-metal, stable in air, and in boiling H2O, insoluble in HC1, but dissolved by HNOj or aqua regia to form telluric acid. The element is dissolved by NaOH solution and combines with chlorine upon heating to form tellurium tetrachloride. 

During the process some of the tellurium tetrachloride becomes hydrolysed to oxychloride and a portion of the dimethylpyrone appears as dimethylpyrone tellurioxychloride which has the above structure. 

In the series of the binary halides of selenium and tellurium, the crystal structure determinations of tellurium tetrafluoride (100) and of tellurium tetrachloride on twinned crystals (65, 66) were the key to understanding the various and partly contradictory spectroscopic and other macroscopic properties (e.g., 66,161,168,169,219,220, 412), as well as the synthetic potential of the compounds. In contrast to the monomeric molecular i//-tbp gas phase structures with C2v symmetry (417), the solid state structures of both are polynuclear. As the prototype of the chlorides and bromides of selenium and tellurium, crystalline tellurium(IV) chloride has a cubane-like tetrameric structure with approximate Td symmetry (Fig. 1). Within the distorted TeCla+a octa-hedra the bonds to the triply bridging chlorine ligands are much longer than to the terminal chlorines. The bonding system can be described either covalently as Te4Cli6 molecules, or, in an ionic approximation, as [(TeCl Cn4] with a certain degree of stereochemical activity of the lone pairs toward the center of the voluminous cubane center (65, 66). 

TeCl4 (Tellurium Tetrachloride) The structure of TeCl4 is established as distorted trigonal bipyramidal as shown below with one equatorial position occupied by a lone pair. 

Sangokoya, S.A., Pennington, W.T. and Robinson, G.H., Alleviation of tellurium tetrachloride by trimethylaluminum- synthesis and molecular-structure of [Te(CH3)3]... 

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