(Ge4 Bi14 )4- : A Case of "Element Segregation" on the Molecular Level.

Extraction of a solid with the nominal composition "K2 GeBi" with 1,2-diaminoethane (en) in the presence of 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (crypt-222) afforded the salt [K(crypt-222)]4 (Ge4 Bi14 ). The 18-atom Zintl anion (Ge4 Bi14 )4- has a heretofore unknown molecular topology, which can be thought of as the formal condensation product of two E113- cages along a shared Ge4 waist. In this way, (Ge4 Bi14 )4- represents the largest and most structurally complex Bi-containing polyanion. We describe its stepwise formation, its geometric and electronic structure, and comment on relative stabilities of isomers with different distributions of the four Ge atoms on the 18 positions that were investigated using DFT calculations.