Alloying Engineering of Defective Molybdenum Sulfide Basal Planes for Enhanced Borrowing Hydrogen Activity in the Thioetherification of Alcohols

The borrowing hydrogen thioetherification of alcohols over heterogeneous catalysts has emerged as an attractive and practical synthetic strategy to prepare thioethers from the perspective of green and sustainable chemistry. Developing efficient catalysts is the key to improve this carbon-sulfur (C-S) bond formation process. Herein, a novel catalyst, namely {Mo_2.89W_0.11S₄}_n, has been prepared by alloying engineering of its basal planes through an innovative synthetic methodology that makes use of isostructural building entities based on molybdenum and tungsten sulfide molecular complexes with M₃S₄ (M=Mo, W) cluster cores. Besides excellent activity and reusability, {Mo_2.89W_0.11S₄}_n is of broad scope, enabling the conversion of structurally diverse thiols and primary as well as secondary alcohols into thioethers. A set of characterizations, in combination with catalytic results, reveal that the catalytic activity of {Mo_2.89W_0.11S₄}_n for this relevant transformation arises from the presence of multiple-type active centers in the defective basal planes of this alloyed catalyst. More specifically, coordinatively unsaturated sulfurs and metal atoms with Lewis basic and Lewis acid properties, respectively, are proposed to be the active sites involved in the borrowing hydrogen mechanism.