Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 57. Reactions of iron–molybdenum complexes with oxygen and sulphur; crystal structure of [FeMo(µ-η2-SCC6H4Me-4)(CO)5(η-C5H5)]

Abstract

The compound [FeMo(µ-CR)(CO)₆(η-C₅H₅)](R = C₆H₄Me-4), in diethyl ether at room temperature, reacts with molecular oxygen to give the complex [FeMo{µ-C(R)C(O)O}(CO)₅(η-C₅H₅)] in which the bridging ligand has formed by coupling of an oxygen atom with CO and CR groups. Treatment of tetrahydrofuran (thf) solutions of [FeMo(µ-CR)(CO)₆(η-C₅H₅)] with elemental sulphur at room temperature affords a mixture of the complexes [FeMo{µ-C(R)C(O)S}(CO)₅(η-C₅H₅)] and [FeMo(µ-η²-SCR)(CO)₅(η-C₅H₅)]. The structure of the latter has been established by an X-ray diffraction study. The Fe–Mo bond [2.765(1)Å] is transversely bridged by the SCR group [µ-C–S 1.735(2), Fe–S 2.248(1), Mo–S 2.441 (1), µ-C–Fe 1.942(2), and µ-C–Mo 2.153(2)Å]. The iron atom carries three terminally bonded CO groups, and the molybdenum atom is ligated by the η-C₅H₅ ring and two CO groups, one Mo–C–O bond being slightly bent [170.4(2)°]. The reaction between sulphur and the trimetal complex [Fe₂Mo(µ₃-CR)(µ-CO)(CO)₈(η-C₅H₅)] in thf at room temperature gives a mixture of the two trimetal complexes [Fe₂Mo(µ₃-η²-SCR)(CO)₈(η-C₅H₅)] and [Fe₂Mo(µ-CR)(µ₃-S)(CO)₇(η-C₅H₅)]. The former is quantitatively converted into the latter with loss of CO on heating in toluene. Spectroscopic data for the new compounds are reported and discussed.