Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes

Summary, in English

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 ⁴E excited state, which has been postulated to be involved in a two-state reactivity model, and 2)the Mn^III/IV reduction potentials.

• Author: Allyssa A. Massie; Melissa C. Denler; Luísa Thiara Cardoso; Ashlie N. Walker; Kamal Hossain; Victor W. Day; Ebbe Nordlander; Timothy A. Jackson
• Department/s: Chemical Physics
• Publishing year: 2017
• Language: English
• Pages: 4178-4182
• Publication/Series: Angewandte Chemie (International edition)
• Volume: 56
• Issue: 15
• Links: http://dx.doi.org/10.1002/anie.201612309
• Document type: Journal article
• Publisher: John Wiley & Sons Inc.
• Topic: Materials Chemistry; Physical Chemistry (including Surface- and Colloid Chemistry)
• Keywords: C-H activation; Hydrogen atom transfer; Kinetics; Manganese; Metal-oxo compounds
• Status: Published
• ISBN/ISSN/Other: ISSN: 1433-7851