Die Monoantimonide RbSb und CsSb / The Monoantimonides RbSb and CsSb

Abstract

The alkali metal monoantimonides RbSb and CsSb were synthesized from the elements in sealed quartz ampoules. These compounds crystallize in the NaP-type structure (RbSb: P212121 (No. 19), a = 731.5pm, b = 719.7 pm, c = 1281.5 pm, Z = 8; CsSb: P212121 (No. 19), a = 757.6 pm, b = 734.5 pm, c = 1327.3 pm, Z = 8). The main feature of the structures are 1 ∞[Sb-] chains parallel to the 5-axis with bond distances. d̄(Sb-Sb) = 285.8 pm and 285.3 pm, respectively. These bond lengths are discussed in detail relative to those in elementary antimony and to the tetrahedral or covalent radii. The volume increment of Sb- can be derived to be 29.8 cm3 · mole-1.