K₆Sn₂₃Bi₂ und K₆Sn₂₅ - Zwei phasen mit chiraler clathrat-struktur und ihr verhalten gegenüber ethylendiamin

K₆Sn₂₃Bi₂ was prepared from the elements in a sealed niobium tube at 620°C. A single crystal of the composition K₆Sn₂₅ could be isolated from the reaction of a solidified melt of nominal composition "K₄Sn₉" and 18crown6 (1,4,7,10,13,16-hexaoxacyclooctadecane) at 45°C. K₆Sn₂₃Bi₂ and Kn₆Sn₂₅ are isotypic and adopt the chiral cubic clathrate structure type cP124. Both crystal structures were determined from single crystal X-ray data: space group P4₃32, a = 16,300(2) and 16,202(2) Å, respectively, Z = 4. The structures contain one kind of a distorted pentagonal dodecahedron of the elements Sn/Bi and Sn, respectively, as the only building block. The pentagonal dodecahedron is centered with potassium and linked by three pentagonal faces and one external bond to four others. Thus leading to a three-dimensional, chiral zeolite-like network. The resulting voids and channels are occupied by potassium. There are 17 four-and 8 three-connected atoms out of every 25 framework atoms. The reactions of the title compounds as well as of solidified melts of the compositions K: Sn = =x: 25 (x = 4; 5; 8; 11 and 22) with ethylenediamine are discussed.