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 ](3-) "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 ](2-) 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 ](3-) ion-and indicate the possibility of the generation and isolation of further, large bismuth polyanions.