A High-Valent Non-Heme μ-Oxo Manganese(IV) Dimer Generated from a Thiolate-Bound Manganese(II) Complex and Dioxygen

Abstract

This study deals with the unprecedented reactivity of dinuclear non-heme Mn^II -thiolate complexes with O₂ , which dependent on the protonation state of the initial Mn^II dimer selectively generates either a di-μ-oxo or μ-oxo-μ-hydroxo Mn^IV complex. Both dimers have been characterized by different techniques including single-crystal X-ray diffraction and mass spectrometry. Oxygenation reactions carried out with labeled ¹⁸ O₂ unambiguously show that the oxygen atoms present in the Mn^IV dimers originate from O₂ . Based on experimental observations and DFT calculations, evidence is provided that these Mn^IV species comproportionate with a Mn^II precursor to yield μ-oxo and/or μ-hydroxo Mn^III dimers. Our work highlights the delicate balance of reaction conditions to control the synthesis of non-heme high-valent μ-oxo and μ-hydroxo Mn species from Mn^II precursors and O₂ .

Keywords: Homogeneous catalysis; O2 activation; manganese; mechanistic studies; sulfur ligands.