Unveiling the Unique Reactivity of Anionic Mn(I) Complexes via Metal–Ligand Cooperation: Nucleophilic Attack on C(sp3)–X Bonds

• Published in: Journal of the American Chemical Society Vol. 146; no. 39; pp. 26649 - 26656
• Main Authors: Li, Hengxu, Fan, Mingjie, Liu, Qiang
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.10.2024
• Subjects: catalytic activity; cross-coupling reactions; dehydrogenation; hydrogenation; Lewis acids; Lewis bases; ligands; manganese; reducing agents
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c01683

Metal–ligand cooperation (MLC) has emerged as a pivotal strategy for the catalytic activation of small molecules within both synthetic and biological arenas. Leveraging this approach, a suite of potent catalytic reactionsencompassing hydrogenation, hydroelementation, and dehydrogenative processeshave been realized, with notable advances in manganese catalysis in recent years. However, the activation of alkyl halides by Mn complexes, which typically requires strong reductants to form Mn­(–I) complexes that are incompatible with standard cross-coupling conditions, remains a significant challenge. This limitation underscores the urgent need to investigate alternative methods for activating C­(sp3)–X bonds using higher valence state Mn complexes. In response to this challenge, we present the synthesis, characterization, and reactivity of a new anionic Mn­(I) complex featuring a redox-active dianionic ligand that induces multiple MLC functionalities. We have discovered an innovative mechanism of MLC, characterized by a single ligand transferring two electrons to the metal center. This novel process facilitates an orbital-symmetry-allowed nucleophilic attack on C­(sp3)–X bonds, preserving manganese’s oxidative state at +1. To the best of our knowledge, this is the first instance where the MLC strategy via a two-electron transfer process has been utilized to execute an SN2 nucleophilic attack at a C­(sp3)–X bond by a relatively electron-deficient metal center like Mn­(I). Additionally, the dianionic ligand of the anionic Mn­(I) complex exhibits ambident nucleophilicity by reacting with different electrophiles, further highlighting its versatile reactivity.