Epoxidations catalyzed by an ionic manganese(III) porphyrin and characterization of manganese(V, IV)-oxo porphyrin complexes by UV-vis spectrophotometer in ionic liquid solution

An ionic metalloporphyrin of manganese tetrakis-(4-N-trimethylaminophenyl)porphyrin hexafluorophosphate ([Mn(III)TTMAPP][PF6](5), 1c), resided in the mixed ionic liquids (ILs) of [BzMIM]BF4 and [BMIM]BF4, proved to bean efficient and recyclable catalytic system for styrene (derivative) epoxidations without the involvement of the auxiliary axial ligands. The epoxidation rate in 1c-IL could be dramatically promoted by addition of water. In the built-up 1c-IL-H2O system, the active manganese(V)-oxo porphyrin intermediate (1d, 444 nm) was stabilized to facilitate its detection by a UV-vis spectrophotometer. And the formation of the mu-oxo Mn(IV) porphyrin dimer (1e, 416nm) was completely suppressed due to the counteraction between 1c and the IL. (c) 2008 Elsevier B.V. All rights reserved.