Syntheses and characterization of some mixed Te/Se polychalcogenide anions [TemSen]2-

Several mixed Te/Se polychalcogenide anions [TemSen](2-) were synthesized at 293 K by reactions between Te(n)(2-)and Se-n(2-) anions in N,N-dimethylformamide (DMF) in the presence of different-size ammonium or phosphonium cations, in some cases in the presence of metal species. The structures of these anions were determined by single-crystal X-ray diffraction methods. The crystal structures of (NEt4](2)[Te3Se6] (1) and [NEt4](2)[Te3Se7] (2) consist, respectively, of one-dimensional infinite infinity(1)[Te3Se62-] and infinity(1)[Te3Se72-] anionic chains separated by NEW cations. In compound 1, each chain comprises Te3Se5 eight-membered rings bridged by Se atoms. The Te3Se5 ring has an "open book" conformation. The NMR spectrum of a DMF solution of [NEt4](2)[Te3Se6] crystals at 223 K shows Se-77 resonances at delta = 290, 349, and 771 ppm and a single Te-125 resonance at delta = 944.7 ppm. In compound 2, each chain comprises Te3Se6 five- and six-membered rings bridged by Se atoms. The Te3Se6 ring can be regarded as an inorganic analogue of bicyclononane. The anion of [PPh4](2)[Te2Se2] (4) contains a Se-Te-Te-Se chain with the terminal Se atoms trans to one another. The new compounds [PPN](2)[TeSe10] (3), [NMe4](2)[TeSe3](DMF)-D-. (5), and [NEt4](2)[TeSe3] (6) contain known anions.