Synthesis, Structure, and Theoretical Study of the Nonclassical [CuTe₇]^3- Anion

The compound [PPh4]2[NEt4][CuTe7] has been synthesized from the reaction of CuCl with a polytelluride solution in dimethylformamide at room temperature. The compound crystallizes with two formula units in the triclinic space group P1̄ in a cell with dimensions a = 8.9507(18) Å, b = 14.714(3) Å , and c = 23.277(5) Å and α = 86.32(3)°, β = 80.17(3)°, and γ = 75.63(3)° (T = −120 °C). Ab initio calculations indicate that the nonclassical [CuTe7]3- anion is the result of joining Te32- and [CuTe4]1- fragments through donor−acceptor interactions.