Synthesis, crystal structure and properties of K2Ta 2S10: A novel ternary tantalum polysulfide with TaS 8 polyhedra forming infinite anionic chains

Article abstract of DOI:10.1016/j.jssc.2005.02.010

The new ternary alkali tantalum polysulfide K₂Ta ₂S₁₀ has been synthesized by reacting TaS₂ with an in situ formed melt of K₂S₃ and S at 773 K. The compound crystallizes with four formula units in the monoclinic space group P2₁/n (No. 14) with lattice parameters of a=14.9989(13)A,b=6. 4183(4)A,c=15.1365(13)A,β=117.629(9)°. The structure contains two different zigzag chain anions [TaS₅]^-, running parallel to the crystallographic b-axis separated by potassium cations. The two crystallographically independent tantalum atoms are in a distorted bi-capped trigonal prismatic environment of eight sulfur atoms which was never observed before. The TaS₈ polyhedra share three S atoms on each side to form the anionic chains. The compound was characterized with FIR and Raman spectroscopy.