In:
Angewandte Chemie, Wiley, Vol. 129, No. 15 ( 2017-04-03), p. 4242-4246
Abstract:
Manganese(IV)‐oxo complexes are often invoked as intermediates in Mn‐catalyzed C−H bond activation reactions. While many synthetic Mn IV ‐oxo species are mild oxidants, other members of this class can attack strong C−H bonds. The basis for these reactivity differences is not well understood. Here we describe a series of Mn IV ‐oxo complexes with N5 pentadentate ligands that modulate the equatorial ligand field of the Mn IV center, as assessed by electronic absorption, electron paramagnetic resonance, and Mn K‐edge X‐ray absorption methods. Kinetic experiments show dramatic rate variations in hydrogen‐atom and oxygen‐atom transfer reactions, with faster rates corresponding to weaker equatorial ligand fields. For these Mn IV ‐oxo complexes, the rate enhancements are correlated with both 1) the energy of a low‐lying 4 E excited state, which has been postulated to be involved in a two‐state reactivity model, and 2) the Mn III/IV reduction potentials.
Type of Medium:
Online Resource
ISSN:
0044-8249
,
1521-3757
DOI:
10.1002/ange.v129.15
DOI:
10.1002/ange.201612309
Language:
English
Publisher:
Wiley
Publication Date:
2017
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