Journal of Molecular Catalysis A-Chemical, Vol.219, No.2, 209-216, 2004
Catalytic activities of oxo-Mn-triazacyclononane complexes: spectral studies and single crystal X-ray structure of [Mn4O6(1,4,7-triazacyclononane)(4)] (ClO4)(4)center dot H2O
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 Fr-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. (C) 2004 Elsevier B.V. All rights reserved.
Keywords:oxo-Mn complexes;triazacyclononane complexes of Mn;oxidation of ethylbenzene;peroxidases;catalase activity;x-ray structure;spectroscopic characterization