A Mild and Chemoselective Reduction of Nitro and Azo Compounds Catalyzed by a Well‐Defined Mo3S4 Cluster Bearing Diamine Ligands

Abstract Herein, we report a novel well‐defined diamino Mo 3 S 4 ‐based catalyst system for the reduction of nitroarenes and azo compounds to the corresponding anilines with silanes as reducing agents. This catalytic protocol provides a facile route to access aromatic amines under mild conditions in good to excellent yields. Notably, even anilines functionalized with other potentially reducible moieties are obtained with high selectivity. The new chemoselective catalyst of formula [Mo 3 S 4 Cl 3 (dmen) 3 ](BF 4 ) (dmen: N , N ′‐dimethylethylenediamine) is conveniently synthesized through coordination of the diamine ligand to the incomplete Mo 3 S 4 cubane‐type cluster core in a one‐pot two‐step procedure. The crystal structure of the [Mo 3 S 4 Cl 3 (dmen) 3 ] + cation confirms the formation of a single isomer in which the chlorine atom lies trans to the bridging sulfur atom to afford a C 3 symmetry complex with intrinsic backbone chirality. The structure is preserved in solution, as evidenced by multinuclear NMR spectroscopy and electrospray‐ionization mass spectrometric techniques.