The new layered ternary chalcogenides Ta2NiSe7 and Ta2PtSe7 have been prepared and characterized. These compounds crystallize in the monoclinic space group with four formula units in the cell (for Ta2NiSe7a = 13.827 (3) A, b = 3.482 (1) A, c = 18.577 (4) A, and β = 108.80 (1)° and for Ta2PtSe7a = 13.954 (13) Å, b- 3.530 (3) A, c = 18.694 (17) A, and β = 109.28 (3)°, both at -150 °C). The layers are comprised of Ta atoms in octahedral and bicapped-trigonal-prismatic chalcogen environments and Ni or Pt atoms in octahedral sites. Each Ni or Pt atom is shifted from the center of the octahedron toward one apex, resulting in square-pyramidal coordination. The structure contains one Se-Se pair (d = 2.549 (3) A for Ta2NiSe7 and d = 2.597 (4) A for Ta2PtSe7) in each trigonal prism of Se atoms. The transport properties of Ta2NiSe7 reveal that this material is metallic (σrt= 310 Ω-1 cm-1) and diamagnetic (xrt = -1.54X 10-7emu g-1).
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry