Mixed-chalcogenide, mixed-metal carbonyl clusters. Synthesis and characterization of Cp(2)Mo(2)Fe(2)(mu(4)-Te)(mu(3)-E')(CO)(6) (E,E'=Te; E=S,E'=Te; E,E'=S; E=S, E'=Se), Cp(2)Mo(2)Fe(2)(mu(3)-Te)(mu(3)-E)(CO)(7), and Cp(2)Mo(2)Fe(mu(3)-E)(CO)7 (E=S, TE)

Reflux of a benzene solution of Fe3STe(CO)(9) and Cp(2)Mo(2)(CO)(6) yielded the new cluster Cp(2)Mo(2)Fe(2)STe(CO)(7) (6) as the major product and the following clusters in smaller amounts: Cp(2)Mo(2)Fe(2)Te(3)(CO)(6) (1), Cp(2)Mo(2)Fe(2)STe(2)(CO)(6) (2), Cp(2)Mo(2)Fe(2)S(2)Te(CO)(6) (3), Cp(2)-Mo2FeTe(CO)(7) (4), Cp(2)Mo(2)FeS(CO)(7) (5), and Cp(2)Mo(2)Fe(2)Te(2)(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, Cp(2)Mo(2)Fe(2)SSeTe(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 mu(4)-Te atom and two mu(3)-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 mu(3)-S ligand and the other by a mu(3)-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 earbonyl 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