THE STABILIZATION OF THE RB- ION IN NA16RB7SB7=NA-16(RBRB6)SB-7

An unusual electron distribution is shown by the ternary antimonide Na16Rb7Sb7, since only 21 of the 23 valence electrons of the alkali metal atoms are required for the formation of the Sb3− centers to be expected because of the semiconducting behavior. The remaining two electrons are localized in the region of a Rb center, which is located inside a Rb6 octahedron. The formulation of this center as Rb− is supported for example by the synthesis of the isostructural Na16Rb6ISb7 and by the results of quantum chemical calculations. Copyright © 1995 by VCH Verlagsgesellschaft mbH, Germany