Mixed-Chalcogenide, Mixed-Metal Carbonyl Clusters. Synthesis and Characterization of Cp₂Mo₂Fe₂(μ₄-Te)(μ₃-E)(μ₃-E‘)(CO)₆ (E, E‘ = Te; E = S, E‘ = Te; E, E‘ = S; E = S, E‘ = Se), Cp₂Mo₂Fe₂(μ₃-Te)(μ₃-E)(CO)₇, and Cp₂Mo₂Fe(μ₃-E)(CO)₇ (E = S, Te)

Abstract

Reflux of a benzene solution of Fe3STe(CO)9 and Cp2Mo2(CO)6 yielded the new cluster Cp2Mo2Fe2STe(CO)7 (6) as the major product and the following clusters in smaller amounts: Cp2Mo2Fe2Te3(CO)6 (1), Cp2Mo2Fe2STe2(CO)6 (2), Cp2Mo2Fe2S2Te(CO)6 (3), Cp2Mo2FeTe(CO)7 (4), Cp2Mo2FeS(CO)7 (5), and Cp2Mo2Fe2Te2(CO)7 (7). The new cluster 3 was formed in good yield when a benzene solution of 6 was refluxed with sulfur powder. Similarly, 2 was obtained when a benzene solution of 6 was refluxed with tellurium powder. A new cluster with three different chalcogen ligands, Cp2Mo2Fe2SSeTe(CO)6 (8), was obtained when a benzene solution of 6 was refluxed in the presence of selenium powder. Structures of 1−4, 6, and 8 were established by crystallographic methods. The structures of 1−3 and 8 consist of Mo2Fe2 butterfly cores with a μ4-Te atom and two μ3-chalcogen atoms (1, Te and Te; 2, S and Te; 3, S and S; 8, S and Se) capping the two Mo2Fe faces. Each Mo atom has a Cp ligand, and each Fe atom has three terminally bonded carbonyl groups. The structure of 4 conists of a Mo2FeTe tetrahedron with each Mo possessing a Cp ligand and two terminally bonded carbonyl groups and the Fe atom having three terminal carbonyl groups attached to it. The structure of 6 consists of a Mo2Fe2 tetrahedron. One Mo2Fe face is capped by a μ3-S ligand and the other by a μ3-Te atom. The Fe−Fe bond is bridged by a carbonyl group; there are two terminally bonded carbonyl groups attached to each Fe atom. A semitriply bridging carbonyl group is attached to one Mo atom. The other Mo atom has one terminal carbonyl group. Each Mo atom has one Cp ligand attached to it.