Open AccessMnIV-Oxo complex of a bis(benzimidazolyl)-containing N5 ligand reveals different reactivity trends for MnIV-oxo than FeIV-oxo species
Author(s) -
Melissa C. Denler,
Allyssa A. Massie,
Reena Singh,
Eleanor Stewart-Jones,
Arup Sinha,
Victor W. Day,
Ebbe Nordlander,
Timothy A. Jackson
Publication year - 2019
Publication title -
dalton transactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.98
H-Index - 184
eISSN - 1477-9234
pISSN - 1477-9226
DOI - 10.1039/c9dt00308h
Subject(s) - ligand (biochemistry) , reactivity (psychology) , chemistry , manganese , medicinal chemistry , stereochemistry , crystallography , receptor , organic chemistry , biochemistry , medicine , alternative medicine , pathology
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 MnII and MnIV-oxo complexes were generated and characterized. The [MnIV(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 MnIV-oxo complexes with neutral, pentadentate N5 supporting ligands. The near-IR electronic absorption band maximum of [MnIV(O)(2pyN2B)]2+, as well as DFT-computed metric parameters, are consistent with the equatorial (N-methyl)benzimidazolyl ligands being stronger donors to the MnIV center than the pyridyl and quinolinyl ligands found in analogous MnIV-oxo complexes. The hydrogen- and oxygen-atom transfer reactivities of [MnIV(O)(2pyN2B)]2+ were assessed through reactions with hydrocarbons and thioanisole, respectively. When compared with related MnIV-oxo adducts, [MnIV(O)(2pyN2B)]2+ showed muted reactivity in hydrogen-atom transfer reactions with hydrocarbons. This result stands in contrast to observations for the analogous FeIV-oxo complexes, where [FeIV(O)(2pyN2B)]2+ was found to be one of the more reactive members of its class.