Single-crystal structure of tantalum sulfide (Ta3S2). Structure and bonding in the Ta6Sn (n = 1,3,4,5?) pentagonal-antiprismatic chain compounds
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The single-crystal structure of the new binary sulfide Ta3S2 is reported and discussed in light of the known structures of Ta6S, Ta2S, and the as yet unrealized one-dimensional Ta6S5 chain. Ta2S2 crystallizes in the orthorhombic space group Abm2 (No. 39) with lattice parameters a = 7.4783 (6) Å, b = 17.222 (1) Å, c = 5.6051 (4) Å, V = 721.88 (9) Å3, and Z = 8. While the structure is in accord with that reported for Ta3S2-x (0.2 ≤ x ≤ 0.28) by Wada and Onoda using X-ray Rietveld analysis, we find Ta3S2 to be a stoichiometric compound with no appreciable phase width up to 1300 °C. Band structure calculations reveal that as sulfur content in the Ta6Sn (n = 1, 3, 4, 5) series increases, the Ta-Ta bonding remains optimal, as judged by the behavior of COOP curves for the metal-metal bonding in these compounds. While Ta2S should be an electrical conductor, Ta3S2 should be a poor conductor or semimetallic and Ta6S5 chains are predicted to be semiconducting. © 1991, American Chemical Society. All rights reserved.
author list (cited authors)
Kim, S. J., Nanjundaswamy, K. S., & Hughbanks, T.