K6Cd4Sn3Se13: A Polar Open‐Framework Compound Based on the Partially Destroyed Supertetrahedral [Cd4Sn4Se17]10‐ Cluster.

K6Cd4Sn3Se13 forms in superheated water and has a polar open-framework structure that is based on an octahedral topological motif. It forms from the polymerization of a single [Cd4Sn3Se13]6− cluster which formally derives from a [Cd4Sn4Se17]10−via elimination of one [SnSe4]4− anion. K6Cd4Sn3Se13 exhibits facile ion-exchange properties with suitably sized cations.