Mechanochemical Cascade Synthesis of Zinc Complexes for Catalytic C–S Coupling in One-Pot

The mechanochemical approach to transition metal catalysis offers a number of advantages, including a reduction in solvent usage and an acceleration of reaction times. This study elucidates a one-pot, two-step cascade catalytic synthesis enabled by mechanochemistry, which integrates the synthesis of bidentate zinc complexes and their application in carbon–sulfur coupling reactions. The zinc complexes were systematically modified by altering the halogen atoms attached to the metal center, utilizing the reduced Schiff base ligand N,N’-diphenylethylenediamine, which significantly influenced the catalytic efficiency. Under optimal conditions, a wide range of thioether products were synthesized, demonstrating broad applicability across various substrates. The mechanistic insights were enhanced through the execution of free radical trapping experiments and analysis of reaction intermediates, revealing an S_N2 substitution mechanism in the formation of carbon–sulfur bond. Furthermore, the methodology adheres to green chemistry principles, as evidenced by the favorable green chemistry metrics obtained, indicating a sustainable and eco-friendly protocol for practical use.