Synthesis and spectroscopic characterization of new mixed-metal, mixed-chalcogenide clusters [Fe2W(CO)(10)(mu(3)-Se)(mu(3)-E)] (E=Te or S). Structures of [Fe(2)M(CO)(10)(mu(3)-Se)(mu(3)-E)] (M=W, E=Se or Te; M=Mo, E=Se)

The room-temperature reaction of [Fe-2(CO)(6)(mu-SeTe)] and [Fe-2(CO)(6)(mu-SSe)] with freshly prepared [W(CO)(5)(thf)] (thf = tetrahydrofuran) yielded the new mixed-metal, mixed-chalcogenide clusters [Fe2W(CO)(10)(mu(3)-Se)(mu(3)-E)] (E = Te 1 or S 2). Compounds 1 and 2 were characterized by IR and C-13, Se-77 and Te-125 NMR spectroscopy. The crystal structure of I was elucidated by X-ray diffraction methods. The previously reported compounds [Fe2W(CO)(10)(mu(3)-Se)(2)] 3 and [Fe2Mo(CO)(10)(mu(3)-Se)(2)] 4 were further characterized by Se-77 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.