Catalytic olefin epoxidation with cyclopentadienyl-molybdenum complexes in room temperature ionic liquids

Complexes of the type (η⁵-C₅R₅)Mo(CO)₃X (X = Me, Cl; R = H, Me), being efficient homogeneous catalysts for the epoxidation of olefins, have been examined for their catalytic performance at 55 °C in systems containing room temperature ionic liquids (RTILs) of composition BMIM]NTf₂, BMIM]PF₆, C₈MIM]PF₆ and BMIM]BF₄. The catalytic performance for cyclooctene epoxidation depends strongly on the water content of the system, the catalyst solubility in the RTIL, and the reaction behaviour of the RTIL under the applied reaction conditions. The catalysts can be recycled without significant loss of activity when a reaction system containing BMIM]NTf₂ and BMIM]PF₆ in a 4:1 relationship is used. High proportions of BMIM]PF₆ lead to a ring opening reaction (diol formation), due to HF formation and the presence of residual water.