Synthesis of tantalum tellurides. The crystal structure of Ta2Te3

Article abstract of DOI:10.1016/0925-8388(92)90532-E

Ta₂Te₃ was prepared by reducing TaTe₂ with tantalum at 1350 K in a sealed molybdenum crucible. Ta₂Te₃ disproportionates above 1420 K yielding the ditelluride and as yet unknown Ta₆Te₅. The stability limit for the substitutional sesquitellurides Nb_xTa_2-xTe₃ is reached at x = 1. The novel layered-type structure of Ta₂Te₃ (C 2/m, N = 4; a = 2049.5(3) pm, b = 349.96(4) pm, c = 1223.7(2) pm, β = 143.74(1)° (Guinier), N(I₀) = 762 with I₀ > 2?(I₀), 32 variables, R = 0.032) can be considered a stuffed variant of a molybdenite structure type. It consists of corrugated layers _∞²(Te-Ta_4/3-Te) which, according to the shortest interlayer contacts Te-Te (372.9 pm), order via van der Waals interactions. Extended homonuclear bonding regions (297.1 pm ≤ d_Ta-Ta ≤ 309.7 pm) within the metal layers contribute to the stability of the metallic sesquitelluride.