A Manganese(V)-Oxo Tetraamido Macrocyclic Ligand (TAML) Cation Radical Complex: Synthesis, Characterization, and Reactivity Studies

Deepika G Karmalkar; Xiao-Xi Li; Mi Sook Seo; Muniyandi Sankaralingam; Takehiro Ohta; Ritimukta Sarangi; Seungwoo Hong; Wonwoo Nam

doi:10.1002/chem.201804898

A Manganese(V)-Oxo Tetraamido Macrocyclic Ligand (TAML) Cation Radical Complex: Synthesis, Characterization, and Reactivity Studies

Chemistry. 2018 Dec 5;24(68):17927-17931. doi: 10.1002/chem.201804898. Epub 2018 Nov 19.

Authors

Deepika G Karmalkar¹, Xiao-Xi Li¹, Mi Sook Seo¹, Muniyandi Sankaralingam¹, Takehiro Ohta², Ritimukta Sarangi³, Seungwoo Hong⁴, Wonwoo Nam¹

Affiliations

¹ Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea.
² Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH LP Center, Hyogo, 679-5148, Japan.
³ Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, California, 94025, USA.
⁴ Department of Chemistry, Sookmyung Women's University, Seoul, 04310, Korea.

Abstract

A mononuclear manganese(V)-oxo complex with tetraamido macrocyclic ligand (TAML), [Mn^V (O)(TAML)]^- (1), is a sluggish oxidant in oxidation reactions. Herein, a mononuclear manganese(V)-oxo TAML cation radical complex, [Mn^V (O)(TAML^+. )] (2), is reported. It was synthesized by reacting [Mn^III (TAML)]^- with 3.0 equivalents of [Ru^III (bpy)₃ ]³⁺ or upon addition of one-electron oxidant to 1 and then characterized thoroughly with various spectroscopic techniques along with DFT calculations. Although 1 is a sluggish oxidant, 2 is a strong oxidant capable of activating C-H bonds of hydrocarbons (i.e., hydrogen atom transfer reaction) and transferring its oxygen atom to thioanisoles and olefins (i.e., oxygen atom transfer reaction).

Keywords: C−H bond activation; manganese; olefin epoxidation; radicals; sulfoxidation.

Abstract

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