SYNTHESIS OF K4ZR3TE17, K4HF3TE17 AND THE STRUCTURE OF K4HF3TE17, A NEW ONE-DIMENSIONAL SOLID-STATE TERNARY POLYTELLURIDE

The compounds K4Zr3Te17 and K4Hf3Te17 have been synthesized through the reaction at 900-degrees-C of Zr or Hf with a K2Te/Te melt as a reactive flux. The compounds crystallize in space group C2h5-P2(1)/c of the monoclinic system with four formula units in cells: a = 10.148 (6) angstrom, b = 28.889 (17) angstrom, c = 11.626 (7) angstrom, beta = 115.21 (2)-degrees (T = 107 K) for K4Hf3Te17; a = 10.146(2) angstrom, b = 29.98 (1) angstrom, c = 11.669 (4) angstrom, beta = 115.01 (3)-degrees (T = 153 K) for K4Zr3Te17. The structure of K4Hf3Te17 has been determined from single-crystal X-ray data. The structure comprises infinite, one-dimensional chains of Hf-centered polyhedra that extend along [101] and are separated from each other by K+ ions. Each Hf atom is eight-coordinate. If the Te-Te maximum bond length is taken to be 2.94 angstrom, then there are six Te2(2-) ligands, one mu-2-eta-1-Te2(2-) ligand, and a mu-Te3(2-) ligand. The composition of the infinite chain is infinity 1[Hf3(Te3)(Te2)7(4-)] with the Hf atoms present in the +4 oxidation state.