New Zr<sub>6</sub>MTe<sub>2</sub> (M = Mn, Fe, Co, Ni, Ru, Pt), Zr<sub>6</sub>Fe<sub>0.6</sub>Se<sub>2.4</sub>, and Zr<sub>6</sub>Fe<sub>0.57</sub>S<sub>2.43</sub> Intermetallics: Structural Links between Binary (Zr,Hf)<sub>3</sub>M Alloys and Porous Metal-Rich Tellurides
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The synthesis of the group IV ternary chalcogenides Zr6MTe2 (M = Mn, Fe, Co, Ni, Ru, Pt) and Zr6Fe1-xQ2+x (Q = S, Se) is reported, as are the single-crystal structures of Zr6FeTe2, Zr6Fe0.6Se2.4, and Zr6Fe0.57S2.43. The structure of Zr6FeTe2 was refined in the hexagonal space group P6̄2m (No. 189, Z = 1) with lattice parameters a = 7.7515(5) Å and c = 3.6262(6) Å, and the structures of Zr6Fe0.6Se2.4 and Zr6Fe0.57S2.43 were refined in the orthorhombic space group Pnnm (No. 58, Z = 4) with lattice parameters a = 12.737(2) Å, b = 15.780(2) Å, and c = 3.5809(6) Å and a = 12.519(4) Å, b = 15.436(2) Å, and c = 3.4966(6) Å, respectively. The cell parameters of Mn-, Co-, Ni-, Ru-, and Pt-containing tellurides were also determined. The Zr6ZTe2 compounds are isostructural with Zr6CoAl2, while Zr6Fe1-xQ2+x (Q = S, Se) were found to adopt a variant of the Ta2P-type structure. Chains of condensed M-centered, tetrakaidecahedra of zirconium constitute the basic structural unit in all these compounds. The modes of cross-linking that give rise to the Zr6FeTe2 and Zr6Fe1-xQ2+x structures, differences among the title compounds, and the influence of chalcogen size differences are discussed. The stoichiometric nature of Zr6FeTe2 and its contrast with sulfur and selenium congeners apparently result from a Te−Fe size mismatch. The importance of stabilization of both Zr6FeSe2 and Zr6FeTe2 compounds by polar intermetallic Zr−Fe bonding is underscored by a bonding analysis derived from electronic band structure calculations.
