Poly‐Hydride [AuI7(PPh3)7H5](SbF6)2 cluster complex: Structure, Transformation, and Electrocatalytic CO2 Reduction Properties.

Hydride AuI 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 [Au7(PPh3)7H5](SbF6)2 (abbrev. Au7H52+), an Au cluster complex containing five hydride ligands, which decomposed to give [Au8(PPh3)7]2+ (abbrev. Au82+) upon exposure to light (300 to 450 nm). The valence state of AuI and H− was verified by density functional theory (DFT) calculations, NMR, UV/Vis and XPS. The two nanoclusters behaved differently in the electrocatalytic CO2 reduction reaction (CO2RR): Au7H52+ exhibited 98.2 % selectivity for H2, whereas Au82+ was selective for CO (73.5 %). Further DFT calculations showed that the H− ligand inhibited the CO2RR process compared with the electron‐donor H. [ABSTRACT FROM AUTHOR]