[As3Br12]3– and [As8I28]4– – Structurally Novel, Discrete Halogenoarsenate( III ) Ions

EF6 octahedra can be linked in a large number of different ways, as demonstrated once again by the preparation of the two title anions, which were obtained as crystalline triethylammonium salts. In [As3Br12]3−, the central AsBr6 octahedron shares two faces having a common corner with two other AsBr6 octahedra. [As8I28,]4− (shown at right) formally consists of eight edge-bridged AsI6 octahedra.