Catalytic activities of oxo–Mn–triazacyclononane complexes: spectral studies and single crystal X-ray structure of [Mn4O6(1,4,7-triazacyclononane)4](ClO4)4·H2O

Abstract

Monomeric terminal-oxo– and tetrameric bridged-oxo–Mn complexes viz., [(tmtacn)Mn(O)(H2O)]SO4, and [Mn4O6(tacn)4](ClO4)4·H2O,respectively, were isolated and characterized by FT-IR, UV–vis, EPR and magnetic susceptibility. Here, tmtacn = N,N,N-trimethyl-1,4,7- triazacyclononane and tacn = 1,4,7-triazacyclononane. Single crystal X-ray structure of the tetrameric bridged-oxo–Mn complex is reported. The catalytic oxidation activities of these complexes for benzylic C–H bond oxidation of ethylbenzene with aqueous H2O2 and tert-butyl hydroperoxide (TBHP) are reported. The studies reveal that nuclearity and type of oxo–Mn speciation influence the catalytic activity. While the monomeric terminal-oxo–Mn complex exhibits efficient C–H bond oxidation activity, the tetrameric bridged-oxo–Mn complex shows the catalase activity.