Using the pentadentate ligand (N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, 2pyN2B), presenting two pyridyl and two (N-methyl)benzimidazolyl donor moieties in addition to a central tertiary amine, new Mn II and Mn IV -oxo complexes were generated and characterized. The [Mn IV (O)(2pyN2B)] 2+ complex showed spectroscopic signatures (i.e., electronic absorption band maxima and intensities, EPR signals, and Mn K-edge X-ray absorption edge and near-edge data) similar to those observed for other Mn IV -oxo complexes with neutral, pentadentate N 5 supporting ligands. The near-IR electronic absorption band maximum of [Mn IV (O)(2pyN2B)] 2+ , as well as DFT-computed metric parameters, are consistent with the equatorial (N-methyl)benzimidazolyl ligands being stronger donors to the Mn IV center than the pyridyl and quinolinyl ligands found in analogous Mn IV -oxo complexes. The hydrogen- and oxygen-atom transfer reactivities of [Mn IV (O)(2pyN2B)] 2+ were assessed through reactions with hydrocarbons and thioanisole, respectively. When compared with related Mn IV -oxo adducts, [Mn IV (O)(2pyN2B)] 2+ showed muted reactivity in hydrogen-atom transfer reactions with hydrocarbons. This result stands in contrast to observations for the analogous Fe IV -oxo complexes, where [Fe IV (O)(2pyN2B)] 2+ was found to be one of the more reactive members of its class. This journal is © The Royal Society of Chemistry 2019.