Chemistry and Catalytic Performance of Pyridyl‐Benzimidazole Oxidomolybdenum(VI) Compounds in (Bio)Olefin Epoxidation

The chemistry and catalytic performance of the dichlorido complex [MoO 2 Cl 2 (pbim)] ( 1 ) [pbim = 2‐(2‐pyridyl)‐benzimidazole] in the epoxidation of olefins is reported. Complex 1 acts as a precatalyst and is more effective with tert ‐butylhydroperoxide (TBHP) as the oxidant than with aq. hydrogen peroxide: the cis ‐cyclooctene (Cy) reaction with TBHP gave 98 % epoxide yield at 70 °C/24 h. Catalyst characterization showed that 1 is transformed in situ to the oxidodiperoxido complex [MoO(O 2 ) 2 (pbim)] ( 2 ), with H 2 O 2 and a hybrid molybdenum(VI) oxide solid formulated as [MoO 3 (pbim)] ( 3 ) with TBHP. The hybrid material 3 was prepared on a larger scale and explored for the epoxidation of the biorenewable olefins methyl oleate, methyl linoleate, and ( R )‐(+)‐limonene. With TBHP as the oxidant, 3 acts as a source of soluble active species of the type 2 . A practical method for recycling oxidodiperoxidomolybdenum(VI) catalysts for the Cy/TBHP reaction is demonstrated by using an ionic liquid as the solvent for the molecular catalyst 2 .