Tribarium pentastannide, Ba3Sn5, is a binary Zintl
phase, not found in the phase diagram presented above.
Sr3Sn5 and Ba3Sn5 were synthesized and structurally
characterized. All compounds are isotypic and crystallize
with a modified Pu3Pd5 structure type. The anionic
substructure is composed of Sn56- square pyramidal clusters,
which are described as arachno clusters according to the Wade–Mingos electron counting rules. The electronic
structure of the pyramidal Zintl anions and the
influence of the number of skeletal electrons of these
clusters were investigated using the ELF.
