A chiral menthyl cyclopentadienyl molybdenum tricarbonyl chloro complex: Synthesis, heterogenization on MCM-41/MCM-48 and application in olefin epoxidation catalysis

The complex [(−)-menthylCp]Mo(CO)3Cl (1) was synthesized by the reaction of Mo(CO)3(EtCN)3 with [(−)-menthylCpH] to produce the hydride [(−)-menthylCp]Mo(CO)3H. The latter compound was then reacted with CCl4 to form [(−)-menthylCp]Mo(CO)3Cl (1). Compound 1 was tested as catalyst for the epoxidation of cis-cyclooctene, styrene and trans-β-methylstyrene in the presence of tert-butyl hydroperoxide (TBHP) at 55 °C using chloroform as solvent. Results under homogeneous conditions prompted the authors to immobilize complex 1 on mesoporous MCM-41 and MCM-48 surfaces leading to the grafted materials AM-41CpMoChi and AM-48CpMoChi. The presence of the organometallic complexes in the materials was confirmed by powder X-ray diffraction, N2 adsorption/desorption isotherms, TEM, EA, FT-IR, 1H MAS NMR and TG-MS. AM-41CpMoChi and AM-48CpMoChi were also tested as epoxidation catalysts. The catalytic examinations also included leaching experiments, and the reusing of the grafted materials for several runs.