Ionothennal reactions of [Ge4Se10](4-) with SnCl4 center dot 5H(2)O yielded [BMMIm](24)[Sn36Ge24Se132] (ZBT-1) and [BMIm](24)[Sn32.5Ge27.5Se132] [ZBT-2; B(M)MIm = 1-butyl-(2,)3-(di)methylimidazolium]. These contain the largest known discrete polyanion consisting only of main-group elements. In spite of a zeolite-related composition, the 192-atom "zeoball" anion adopts a spherical shape, which has been unprecedented in the chemistry of zeolites and their homologues and relatives. Preliminary studies indicated that ZBT-1 traps 12 molecules and induces heterolytic I I bond cleavage.