Extrusion of selenium and tellurium atoms from selenophene and tellurophene by reaction with trinuclear iron, ruthenium, and osmium clusters: crystal structures of [Os6(μ-H)(μ3-Se)(μ4-C4H3)(CO)20] and of [Ru4(μ3-Se)μ-C4H4)(CO)11

Abstract

The trinuclear carbobyl clusters [Fe3(CO)12], [Ru3(CO)12], [Os3(CO)11(MeCN)], and [Os3(CO)10(MeCN)2] react with selenophene and tellurophene (cyclo-C4H4X, X = Se or Te) under mild conditions to give compounds containing the open-chain ligands CHCHCHCHX or the fragments X, C4H4, C4H3, or H as bridging ligands. The following compounds were isolated and characterised: [Os3(CO)10(C4H4X)], 1 where X = Se (X-ray structure reported previously) and 8 where X = Te, [Os6H(Se)(C4H3)(CO)20], 2, [Os2(CO)6(C4H4Se)], 3, [Ru2(CO)6(C4H4)], 4, [Ru4(CO)6(C4H4)], 4, [Ru4(Se)(CO)11(C4H4)], 5, [Fe2(CO)6(C4H4)], 6, and [Fe2(CO)6(C4H4Se)], 7. The clusters 2 and 5 were shown by single-crystal X-ray diffraction methods to have had both SeC bonds broken to give μ3-Se ligands in each case. Compound 2 contains an interesting μ4-C4H3 ligand linking two Os3 units through a μ-alkylidyne bridge, a σ-OsC bond, and an η3-allyl component. Compound 5 has a μ-C4H4 ligand of a type previously found to be formed by alkyne coupling. The other compounds were characterised spectroscopically.