Darstellung und Kristallstruktur von Cs4Se16 / Preparation and Crystal Structure of Cs4Se16

Abstract

The cesium polyselenide Cs4Se16 has been prepared by the methanolothermal reaction of Cs2CO3 and Se at 160 °C and 13 bar. [Se16]4- fragments may be regarded as containing an Se6 ring with Cs symmetry and two Se5 chains related by the crystallographic mirror plane. Se4 of the sixmembered ring, which displays a square planar geometry, participates in two relatively long Se4—Se5 bonds [2.989(4) A] to individual chains. The trans-sited Se4—Se3 bonds [2.425(4) A] are markedly longer than the remaining Se—Se bonds in the Se6 ring [2.344(4), 2.356(4) A]. Further Se—Se interactions of length 3.132(4) and 3.346(4) Å are observed between individual [Se16]4- fragments.