Yasuhiro Ohki

A cubic metal‐sulfur cluster containing three Mo ions and a Pd ion, [Cp SiEt3 3 Mo 3 S 4 Pd]Cl ( Mo 3 Pd , Cp SiEt3 =C 5 Me 4 SiEt 3 ), was synthesized by the incorporation of the Pd ion into a Mo 3 S 4 cluster [Cp SiEt3 3 Mo 3 S 4 ] ( Mo 3 ). Mo 3 Pd was characterized by 1 H NMR, UV‐vis, X‐ray crystallography, and cyclic voltammetry measurements. The electrochemical measurements demonstrated reversible one‐ and two‐electron reduction processes for Mo 3 Pd , which suggested potential catalytic activity for two‐electron substrate reductions such as hydrogen evolution reaction. Controlled potential electrolysis in the presence of Mo 3 Pd and trifluoroethanol in THF solvent displayed H 2 formation with a constant current over 60 min. The amount of generated H 2 by Mo 3 Pd was two times higher than Mo 3 , indicating the catalytic activity facilitated by the Pd center. The mechanism of the catalytic cycle was determined by density functional theory.