Chalcogenides of the transition elements. V. Crystal structures of the disulfides and ditellurides of ruthenium and osmium

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Abstract
The crystal structures of RuS2, OsS2, RuTe2, and OsTe2were refined isotropically by least squares from powder diffractometer data using individual temperature factors. The resulting positional parameters of the chalcogen atoms in these C2-type structures are 0.3879 ± 14, 0.3865 ± 19, 0.3739 ± 9, and 0.3725 ± 18 respectively (for meaning of the uncertainty limits see Table II and text). The structure of Ir3Te8was refined from Hockings and White's published data to give x(Te) = 0.3702 ± 18. The shortest metal–chalcogen distances in these structures are Ru—S 2.351 ± 3 Å, Os—S 2.352 d ± 5 Å, Ru–Te 2.647 ± 3 Å, Os–Te 2.647 ± b 3 Å, and Ir—Te 2.651 ± 4 Å (not corrected for thermal motion). The shortest S–S distances (in the S2groups) are 2.179 ± 30 Å in RuS2and 2.210 ± 46 Å in OsS2. The corresponding shortest Te—Te distances are 2.791 ± fc 35 Å in RuTe2, 2.826 ± 38 Å in OsTe2, and 2.872 ± 30 Å in Ir3Te8(not corrected for thermal motion). Within the stated uncertainty limits the shortest metal–chalcogen distances are independent of the nature of the metal. The shortest chalcogen–chalcogen distances are so sensitive to variations in x that even the above relatively narrow uncertainty limits preclude meaningful statements to be made about the effect of the metal on these distances, with the possible marginal exception of the nonstoichiometric C2 structure Ir3Te8.