Ba@Sn10 and Ru@Sn7/Rh@Sn7 polyhedra as basic building units in the stannides BaT 5-x Sn9 (T = Ru, Rh)

Schwickert C., Rodewald U.C., Pöttgen R.

Zusammenfassung

The tin-rich stannides BaRh5-x Sn9 and BaRu 5-x Sn9 were synthesized by direct reactions of the elements in sealed niobium or tantalum tubes in muffle furnaces. Their structures were refined from X-ray single-crystal diffractometer data: BaCo 4.7Ge9 type, Pnma, Z = 4, a = 1,553.44(8) pm, b = 438.38(2) pm, c = 1,861.5(1) pm, wR = 0.0558, 2,787 F 2 values for BaRh4.43Sn9, a = 1,554.09(6) pm, b = 438.44(1) pm, c = 1,873.44(5) pm, wR = 0.0589, 2,184 F 2 values for BaRh 4.68Sn9, and a = 1,560.7(2) pm, b = 440.24(4) pm, c = 1,869.0(3) pm, wR = 0.0674, 2,197 F 2 values for BaRu 4.57Sn9 with 93 variables per refinement. The Rh5 and Ru5 sites show small defects. The shortest interatomic distances occur for Ru-Sn and Rh-Sn, leading to Ru@Sn7 and Rh@Sn7 building units that derive from an octahedron by replacing one apex by a pair of tin atoms. These units condense by common triangular and rectangular faces forming a three-dimensional network in which the barium atoms fill slightly distorted pentagonal prismatic voids. © 2014 Springer-Verlag Wien.