A Linear Trinuclear Oxidodiperoxido‐molybdenum(VI) Complex with Single Triazole Bridges: Catalytic Activity in Epoxidation, Alcoholysis, and Acetalization Reactions

The complex (Htrz)(2)[Mo3O6(O-2)(4)(trz)(2)]center dot H2O (1), isolated from the reaction of MoO3 with H2O2 in the presence of 1,2,4-triazole (trz), displays singular structural features such as double bridges comprising one oxido and one triazole ligand, and peripheral oxidodiperoxido-molybdenum(VI) units. A comparative study was performed regarding the catalytic activity and stability of complex1 and the hybrid material [MoO3(trz)(0.5)] (2) for the epoxidation of cis-cyclooctene (Cy8), the alcoholysis of epoxides, and the acetalization of benzaldehyde (PhCHO). Methanol or ethanol were used as solvents and reagents for the latter two reactions. For the substrates Cy8, styrene oxide, and PhCHO, the corresponding epoxide, beta-alkoxy alcohol, and dialkyl acetal were obtained with 100% selectivity at very high conversions. In general, 1 performed better than 2 for the different catalytic reactions. Under certain oxidant/co-solvent conditions used for Cy8 epoxidation, 1 was converted to 2 during the reaction.