Formation of [Bi(11)](3-) , a homoatomic, polycyclic bismuth polyanion, by pyridine-assisted decomposition of [GaBi(3)](2-).

Until now, polycyclic bismuth polyanions have not been known-thus discriminating bismuth from its lighter congeners. However, the synthesis of [K([2.2.2]crypt)]3 (Bi11 )⋅2 py⋅tol, allows us to present the first structurally characterized homoatomic, polycyclic bismuth polyanion, which exhibits the P11 "ufosan" structure. It was obtained upon treatment of [K([2.2.2]crypt)]2 (GaBi3 )⋅en with the solvent pyridine. The binary Zintl anion GaBi3 decomposes under oxidative coupling of pyridine molecules and release of H2 to form the title compound. The unprecedented reaction, its products and by-products were investigated by means of spectroscopy, spectrometry, and DFT studies. All findings reveal the specific reaction conditions to be crucial for the formation of the Bi11 ion-and indicate the possibility of the generation and isolation of further, large bismuth polyanions.