Metal-Ligand Cooperative Catalysis by a Well-Defined SNS Pincer Mn(I) Complex for Chemoselective Nitrile Hydration

Herein, we report the design, synthesis, and characterization of an Mn(I) complex (C1) coordinated with an SNS-type pincer ligand L1. Single-crystal X-ray diffraction studies confirms the pincer coordination mode and a distorted octahedral geometry around the metal center. Both the ligand and complex C1 are air-and moisture-stable, remaining intact at room temperature for over one month. The newly synthesized complex C1 was evaluated for the catalytic hydration of aryl and alkyl carbonitriles to the corresponding carboxamides.Optimization studies highlight the crucial role of the well-designed ligand framework in enabling efficient Mn(I)-mediated catalysis. Catalyst C1 exhibits broad substrate scope with excellent functional group tolerance, delivering up to 99% yield. Poisoning experiments indicate a homogeneous catalytic pathway, while radical scavenger tests exclude the involvement of radical intermediates. Based on experimental observations, control studies, and literature precedents, a plausible mechanism emphasizing the key role of metal-ligand cooperativity is proposed.