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Comparison of Co with Mn and Fe in LDH-hosted Sulfonato−Salen Catalysts for Olefin Epoxidation

2008; American Chemical Society; Volume: 112; Issue: 36 Linguagem: Inglês

10.1021/jp804339d

1932-7455

Samiran Bhattacharjee, Trevor J. Dines, James A. Anderson,

Polyoxometalates: Synthesis and Applications

Sulphonato−salen complexes containing Mn(III), Co(III), and Fe(III) metal centers intercalated into Zn/Al layered double-hydroxide (LDH) host have been synthesized and tested as catalysts for the epoxidation of cyclohexene and dicyclopentadiene using pivaldehyde and molecular oxygen at atmospheric pressure and room temperature. Oxidation of cyclohexene gave cyclohexene oxide and 2-cyclohexen-1-one as reaction products, whereas dicyclopentadiene was transformed to the corresponding monoepoxide. Selectivity was found to depend on the central metal ion. Activity (TOF) increased according to LDH−[Fe(Cl)(salen)] < LDH−[Co(Cl)(salen)] < LDH−[Mn(Cl)(salen)] in both case of cyclohexene and dicyclopentadiene epoxidation. The structures of the metal(III) sulfonato−salen complexes were modeled by density functional theory calculations in order to compare differences in dimensions and geometries with differences in gallery height and catalytic behavior.