The first orthotelluric acid polysilylesters: Synthesis and crystal structure of [(Me3SiO)(8)Te2O2] and [(Me4Si2O2)(3)Te]

The compounds [(Me3SiO)(8)Te2O2] (1) and [(Me4Si2O2)(3)Te] (2) have been pr epared in good yields through Bronsted acid-base reaction of Te(OH)(6) with Me3SiNEt2 and Me4Si2(NEt2)(2), respectively. They have been characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction analy ses. The formation of dinuclear 1 is the result of fast intermolecular cond ensation of two partially silylated orthotelluric acid units during the est erification process. Its structure consists of two edge-fused TeO6-octahedr a, bearing a four-membered Te2O2 ring as central motif. In contrast, the ma in structural feature of chiral 2 is a TeO6 octahedron which is fully silyl ated by three bidentate 1,1,2,2-tetramethyldisilanediyl units, resulting in a racemic mixture. The metastability of 2 is remarkable since the Te(+ 6) center usually acts as a strong oxidation reagent toward the Si-Si bond in disilanes. 1 and 2 represent potential starting compounds for molecular Tex Oy aggregates as hybrid components for new glasses by sol-gel procedure.