Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 61. Reactions of iron–molybdenum compounds with tertiary phosphines

Abstract

Treatment of [FeMo(µ-CR)(CO)₆(η-C₅H₅)](R = C₆H₄Me-4) with PMe₃ affords the compound [FeMo(µ-CR)(CO)₅(PMe₃)(η-C₅H₅)], which readily releases a molecule of CO to give the unsaturated species [FeMo(µ-CR)(CO)₄(PMe₃)(η-C₅H₅)]; a process which can be readily reversed. The compound [Mo(CR)(CO)₂(η-C₅H₅)] reacts with PMe₃ to give [Mo(CR)(CO)(PMe₃)(η-C₅H₅)]. The latter on treatment with one equivalent of [Fe₂(CO)₉] yields a mixture of the complexes [FeMo(µ-CR)(CO)_n(PMe₃)(η-C₅H₅)](n= 4 or 5), and with excess of [Fe₂(CO)₉] affords [Fe₂Mo(µ₃-CR)(µ-CO)(CO)₇(PMe₃)(η-C₅H₅)]. This di-ironmolybdenum compound may also be obtained from the reaction of PMe₃ with [Fe₂Mo(µ₃-CR)(µ-CO)(CO)₈(η-C₅H₅)], while the latter with dppm (Ph₂PCH₂PPh₂) affords [Fe₂Mo(µ-CR)(µ-CO)(µ-dppm)(CO)₆(η-C₅H₅)]. The reaction between PMe₃ and [FeMo₂(µ₃-RC₂R)(CO)₆(η-C₅H₅)₂] gives [FeMo₂(µ₃-RC₂R)(CO)₅(PMe₃)(η-C₅H₅)₂]. Spectroscopic data for the new compounds are reported and discussed in the context of the structures proposed.