Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 34. Reactions of sulphur and selenium with the di-irontungsten complexes [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)](R = C6H4Me-4 or Me); crystal structures of [Fe2W(µ-CC6H4Me-4)(µ3-S)(CO)7(η-C5H5)] and [Fe2W(µ3-SCMe)(CO)8(η-C5H5)]

Abstract

The compound [Fe₂W(µ₃-CC₆H₄Me-4)(µ-CO)(CO)₈(η-C₅H₅)] reacts with sulphur or selenium in tetrahydrofuran to afford the complexes [Fe₂W(µ-CC₆H₄Me-4)(µ₃-E)(CO)₇(η-C₅H₅)](E = S or Se). Related tricapping sulphur and selenium complexes have been prepared from the species [Fe₂W(µ₃-CC₆H₄Me-4)(µ-CO)(µ-Ph₂PCH₂PPh₂)(CO)₆(η-C₅H₅)]. The structure of [Fe₂W(µ-CC₆H₄Me-4)(µ₃-S)(CO)₇(η-C₅H₅)] has been established by X-ray diffraction. The sulphur atom asymmetrically bridges the metal atom triangle [Fe–S 2.205(5) and 2.264(7), W–S 2.322(4)Å], and the two Fe–W bonds are asymmetrically bridged by a CO group [W–C–O 163(1)°] and a tolylmethylidyne ligand [µ-C–W 1.87(3), µ-C–Fe 2.12(1)Å], respectively. The methylmethylidyne di-irontungsten cluster [Fe₂W(µ₃-CMe)(µ-CO)(CO)₈(η-C₅H₅)] also reacts with sulphur and with selenium affording the complexes [Fe₂W(µ-CMe)(µ₃-E)(CO)₇(η-C₅H₅)](E = S or Se) and [Fe₂W(µ₃-SCMe)(CO)₈(η-C₅H₅)]. The structure of the latter has been established by X-ray diffraction, leading to the characterisation of the thioacyl ligand which triply bridges the Fe₂W triangle, the C–S vector being parallel to the Fe–Fe edge so that the ligand is σ-bonded to the iron atoms via C–Fe and S–Fe bonds and η²-co-ordinated to the tungsten. In hot tetrahydrofuran, the compound [Fe₂W(µ-SCMe)(CO)₈(η-C₅H₅)] loses a molecule of CO and rearranges to the species [Fe₂W(µ-CMe)(µ₃-S)(CO)₇(η-C₅H₅)], the C–S bond breaking in this process. The n.m.r. data (¹H and ¹³C-{¹H}) for the new compounds are reported and discussed.