Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 17/1997)
The cover picture shows the novel anion[B12(BSe3)6]8−, which was synthesized as the cesium salt by a solid-state reaction from the elements. The icosahedral species is the first example of a new class of polyhedral boron clusters that combines both the structural features of polyhedral boranes and boron chalcogenides. Each boron atom of the B12 icosahedron is coordinated by a selenium atom of one of the six trigonal-planar BSe3 units (depicted as ball-and-stick models). The electron count of the molecular anion obeys Wade's rules. The bidentate binding mode of the BSe3 groups to the B12 polyhedra results in a novel type of planar five-membered B3Se2 rings. The synthesis, structure, and bonding of this first boron icosahedron with complete chalcogen substitution are described by B. Krebs et al. on pages 1903 ff.