Synthesis, Crystal and Electronic Structures, and Electrical Properties of the Fifth Member of the Rb2(Mo9S11)(Mo6 nS6 n+2) Series: Rb10Mo39S43, an Atypical Reduced Molybdenum Sulfide Containing Mo9 and Mo30 Clusters

Abstract

The new compound Rb₁₀Mo₃₉S₄₃ has been synthesized as single crystals by a solid-state reaction in a sealed molybdenum crucible at 1500 °C. It constitutes the fifth member of the homologous series of the trigonal (space group R3̅c) compounds Rb_2n(Mo₉S₁₁)(Mo_6nS_6n+2). Consequently, its crystal structure is based on an equal mixture of Mo₉S₁₁ and Mo₃₀S₃₂ cluster units interlinked through Mo-S bonds with the Rb⁺ cations localized in the voids between the Mo₉S₁₁ and Mo₃₀S₃₂ units. The coexistence of the two high-nuclearity Mo₉ and Mo₃₀ clusters in the crystal structure leads to an unusual c parameter of 163.96(1) Å, and thus, Rb₁₀Mo₃₉S₄₃ is the first ternary and multinary compound in solid-state chemistry to have such a large parameter. Contrary to the first four members, Rb₁₀Mo₃₉S₄₃ was not found to be superconducting down to 2 K. First-principles calculations showed that the electronic structures of this series of compounds can be determined from those of the Mo₉ and Mo_6n clusters and that fewer interactions between clusters in Rb_2n(Mo₉S₁₁)(Mo_6nS_6n+2) occur when n increases.