In situ grafting of cyclopentadienyl-molybdenum complexes on mesoporous materials: The reaction of [η5-CpMo(CO)3]−Na+ with surface fixed iodo-benzyl siloxane

Na+[η5-CpMo(CO)3]− is grafted on aromatic silane (iodo-benzyl trimethoxy silane) modified surfaces of MCM-41 and MCM-48 molecular sieves. The XRD, N2 adsorption–desorption, and TEM analysis provide strong evidence that the mesoporous structure of the supporting materials retains its long range ordering after the grafting process, despite significant reductions of the surface area, pore-volume and pore size. The appearance of strong IR bands around 2016 and 1956 cm−1 as well as 3010 cm−1 on the grafted samples showing the presence of carbonyl as well as aromatic functional groups, evidences the successful grafting of the η5-CpMo(CO)3 complexes. Elemental analysis reveals 6.4 and 8.3 wt% Mo on the SM-41ASG and SM-48ASG samples, respectively. The appearance of new 29Si CP MAS-NMR peaks around −61.4, and −69.6 ppm (T2 and T3) indicates the esterification of silanol groups by the methoxy group of the silane ligand. The samples prepared by this in situ method show high loading of Mo and also good catalytic activity and selectivity for olefin-epoxidation.

Graphical abstractNa+[η5-CpMo(CO)3]− is grafted on aromatic silane (iodo-benzyl trimethoxy silane) modified surfaces of MCM-41 and MCM-48 molecular sieves. Molybdenum loadings of up to 8.3% are reached and the obtained materials are applicable as catalysts for olefin epoxidation.Figure optionsDownload full-size imageDownload as PowerPoint slide