Synthesis and spectroscopic characterization of new mixed-metal, mixed-chalcogenide clusters [Fe₂W(CO)₁₀(μ³-Se)(μ³-E)](E = Te or S). Structures of [Fe₂M(CO)₁₀(μ³-Se)(μ³-E)](M = W, E = Se or Te; M = Mo, E = Se)

Abstract

The room-temperature reaction of [Fe₂(CO)₆(μ-SeTe)] and [Fe₂(CO)₆(μ-SSe)] with freshly prepared [W(CO)₅(thf)](thf = tetrahydrofuran) yielded the new mixed-metal, mixed-chalcogenide clusters [Fe₂W(CO)₁₀(μ³-Se)(μ³-E)](E = Te 1 or S 2). Compounds 1 and 2 were characterized by IR and ¹³C, ⁷⁷Se and ¹²⁵Te NMR spectroscopy. The crystal structure of 1 was elucidated by X-ray diffraction methods. The previously reported compounds [Fe₂W(CO)₁₀(μ³-Se)₂]₃ and [Fe₂Mo(CO)₁₀(μ³-Se)₂]₄ were further characterized by ⁷⁷Se NMR spectroscopy and single-crystal X-ray analysis. Clusters 1, 3 and 4 are isostructural and isomorphous (in the solid state). The structure consists of square-pyramidal Fe₂WSeTe, Fe₂WSe₂ and Fe₂MoSe₂ cores respectively, and in each case the heterometal atom (W for 1 and 3 and Mo for 4) occupies the apical site.