Abstract: | Polyselenides with Long-chain Tetraalkylammonium Ions. Crystal Structure of Trimethyltetradecyl-ammonium Hexaselenide Na2Se2 and Na2Se react with various tetraalkylammonium halides in ethanol and in presence of grey selenium and catalytic quantities of iodine forming different polyselenides Sen2? (n = 3, 5—9). In the solutions equilibria of polyselenides seem to occur; cooling of saturated solutions causes crystallization of polyselenides with a composition depending on the cation. Tri- and pentaselenide are dark green. The higher members form black crystals, all compounds are sensitive to oxygen. The i.r. spectra are reported. [(CH3)3N(CH2)13CH3]2Se6 is characterized by a crystallographic structure determination with X-ray data: space group P21212, Z = 4, a = 5043, b = 734.2, c = 600.3 pm (986 observed independent reflexions. R = 0.072). The compound consists of trimethyl tetradecylammonium ions and angular Se62? chains of symmetry C2 with Se? Se bond lengths of 227 and 235 pm. |