Two metalloid Ga22 clusters containing a novel Ga22 core with an icosahedral Ga12 center

In addition to the two so far known types of metalloid Ga(22) clusters a new type is presented in two compounds containing the anions Ga(22)BrN(SiMe(3))(2)](10)Br(10)](3-) (1) and Ga(22)Br(2)N(SiMe(3))(2)](10)Br(10)](2-) (2). In both anions 10 Ga atoms of the icosahedral Ga(12) core are directly connected to further Ga atoms. The two remaining Ga atoms (top and bottom) of the Ga(12) icosahedron are bonded to one (1) and two Br atoms (2), respectively. The formation and structure of both compounds containing a slightly different average oxidation number of the Ga atoms is discussed and compared especially with regard to the Ga(84) cluster compound and similar metalloid Al(n) clusters. Finally, the consequences arising from the presence of two very similar but not identical Ga(22) cluster compounds are discussed and special consideration is given to the so far not understood physical properties (metallic conductivity and superconductivity) of the Ga(84) cluster compound.