Multifunctional Catalysis of Nanosheet Defective Molybdenum Sulfide Basal Planes for Tandem Reactions Involving Alcohols and Molecular Hydrogen

Abstract

Establishing tandem catalytic synthetic strategies based on the use of readily available, stable, and renewable feedstocks is of great significant for the sustainable advancement of chemical-related industries. The key to success largely relies on applying efficient multifunctional catalysts that allow carrying out one-pot single-step synthesis. In this work, we have demonstrated that defect-engineered basal planes of a molybdenum sulfide nanomaterial ({Mo 3 S 4 } n ) offer a multifunctional catalytic platform for chemical process intensification. By applying this catalyst, besides borrowing hydrogen-type processes, herein exemplified for the thioetherification of alcohols, we have also disclosed novel and rare coupling reactions requiring hydrogen activation and alcohol dehydrogenation processes in a one-pot fashion. More specifically, oxidized nucleophiles, such as o-dinitroarenes and dinitrophenyl disulfides, are reacted with alcohols in the presence of H 2 to yield respectively benzimidazoles and benzothiazoles. The uncommon catalytic reactivity of {Mo 3 S 4 } n arises from the presence of coordinatively unsaturated molybdenum and sulfide species, which work as Lewis acid and Lewis basic sites, respectively. As suggested by in situ infrared (IR) spectroscopy investigations, the alcohol dehydrogenation involves the participation of both types of active sites while the H 2 dissociation takes place on coordinatively unsaturated sulfide species.

From Well-Defined Clusters to Functional Materials: Molecular Engineering of Amorphous Molybdenum Sulfides for Hydrogen Evolution Electrocatalysis

“…The high-resolution Mo 3d XPS core-level spectra showed, after deconvolution and fitting, two sets of doublets, each of them characteristic of the spin–orbit splitting of the Mo 3d 5/2 and Mo 3d 3/2 orbitals. One of these doubles is characteristic of Mo IV species and the other one is ascribed to the presence of molybdenum oxysulfides (Mo v O x S y ). ,, …”

“…In this synthesis, the molecular cluster, composed by three metal atoms defining an equilateral triangle, an apical sulfur atom (Mo 3 -μ 3 -S), and three bridging sulfur ligands (Mo 2 -μ-S), is reduced with hydrazine hydrate, thereby enabling the intercluster self-assembly by nucleophilic attack from the bridging sulfur ligands to the outer coordination sites of Mo atoms . Remarkably, the peculiar structure configuration of these subunits enabled an advanced heterogeneous hydrogenation and dehydrogenation catalyst to be obtained , that displays proliferated structural defects on both the naturally occurring edge positions and along the typically inactive basal planes.…”