The new ternary transition-metal chalcogenides Ta2PdS6, Ta2PdSe6, Nb2PdS6, and Nb2PdSe6 have been prepared. The phases are isostructural. The structures of the phases Ta2PdS6 and Ta2PdSe6 have been established by single-crystal X-ray measurements. [formula omitted] for 1202 observations, 30 variables, [formula omitted] for 1201 observations, 30 variables, R(F) = 0.056 for [formula omitted]. The unit cell parameters of the phases Nb2PdSe6 and Nb2PdSe have been determined from single-crystal and powder X-ray measurements, respectively. Nb2PdSe6 crystallizes in an I-centered cell of dimensions a = 10.368 (1) Å, b = 3.362 (1) Å, c = 12.132 (2) Å, β = 113.42 (2)°, V= 388.0 Å3, and Z = 2. The compound Nb2PdS6 crystallizes in a cell of dimensions a = 9.99 (1) Å, b = 3.30 (1) Å, c = 11.69 (1) Å, β = 114.7 (1)°, and V= 350 Å3. The phases form in a new laminar structural type. Each layer consists of collocated units [formula omitted] (M = Ta or Nb; Q = S or Se) that are composed of MQ3 face-sharing trigonal-prismatic chains bridged by Pd atoms in a square-planar environment of Q atoms. Metrical details and results of electrical conductivity measurements on Ta2PdQ6 indicate the simple valence description TaV, PdII, Q-II.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry