[InAs₃]^6⊖ and [AlSb₃]^6⊖, Trigonal Planar Anions in Cs₆InAs₃ and Cs₆AlSb₃

Abstract

The anions of the complex salts Cs 6 InAs 3 and Cs 6 AlSb 3 are isosteric with borates. Both salts can be obtained as shiny metallic crystals directly from the elements. In the crystal the Cs atoms form a bundle of four chains of trigonal prisms which are centered by the atoms of the trigonal planar anions: {Cs 12/2 [MX 3 ]}. The InAs and AlSb bond lengths (261.5 and 263.7 pm, respectively) fall in the range typical for single bonds.