Inorganic Chemistry, Vol.35, No.24, 6959-6963, 1996
Synthesis and Structure of Ba2Sn3Sb6, a Zintl Phase Containing Channels and Chains
The new Zintl phase dibarium tritin hexaantimonide, Ba2Sn3Sb6 has been synthesized, and its structure has been determined by single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group D-2h(16)-Pnma with a = 13.351(1) Angstrom, b = 4.4100(5) Angstrom, c = 24.449(3) Angstrom, and Z = 4 (T = -50 degrees C). The structure of Ba2Sn3Sb6 comprises large channels [010] defined by 30-membered rings constructed from an anionic framework. This framework is built up from Sn-centered trigonal pyramids and tetrahedra, as well as zigzag chains of Sb atoms. Within the channels reside the Ba2+ cations and additional isolated zigzag Sb-Sb chains. The simultaneous presence of Sn trigonal pyramids and tetrahedra implies that Ba2Sn3Sb6 is a mixed-valence compound whose oxidation state notation can be best represented as (Ba2+)(2)[(Sn-II)(2)(Sn-IV)(Sb--III)(3)(Sb--I)](2-)[(Sb--I)(2)](2-).
Keywords:CRYSTAL-STRUCTURE;ANTIMONIDE TRIANTIMONIDOALUMINATE;CATENA-DIANTIMONIDOGALLATE;ANIONS;ELEMENTS;GALLATE;SB