Poly‐Hydride [Au ^I ₇ (PPh ₃ ) ₇ H ₅ ](SbF ₆ ) ₂ cluster complex: Structure, Transformation, and Electrocatalytic CO ₂ Reduction Properties

Abstract Hydride Au I bonds are labile due to the mismatch in electric potential of an oxidizing metal and reducing ligand, and therefore the structure and structure–activity relationships of nanoclusters that contain them are seldom studied. Herein, we report the synthesis and characterization of [Au 7 (PPh 3 ) 7 H 5 ](SbF 6 ) 2 (abbrev. Au 7 H 5 2+ ), an Au cluster complex containing five hydride ligands, which decomposed to give [Au 8 (PPh 3 ) 7 ] 2+ (abbrev. Au 8 2+ ) upon exposure to light (300 to 450 nm). The valence state of Au I and H − was verified by density functional theory (DFT) calculations, NMR, UV/Vis and XPS. The two nanoclusters behaved differently in the electrocatalytic CO 2 reduction reaction (CO 2 RR): Au 7 H 5 2+ exhibited 98.2 % selectivity for H 2 , whereas Au 8 2+ was selective for CO (73.5 %). Further DFT calculations showed that the H − ligand inhibited the CO 2 RR process compared with the electron‐donor H.