Robust Gold Nanocluster Protected with Amidinates for Electrocatalytic CO Reduction.

The first all-amidinate-protected gold nanocluster [Au (Ph-form) ](OTf) (Ph-form=N,N'-diphenylformamidinate) (Au ) has been synthesized and structurally resolved. Single crystal X-ray diffraction reveals that Au has a compact Au @Au tetrahedral core-shell structure of T symmetry, which is fully protected by 12 bridging formamidinate ligands. This cluster is quite robust as indicated by the fact that it can stay intact in solution at 80 °C for 6 d. It exhibits excellent catalytic performance for the electroreduction of CO with 96.5 % Faradaic efficiency (FE) at -0.57 V and a maximum TOF of 1731 h at -0.87 V. Its superior stability is also manifested in the fact that the supported catalyst Au /CNTs maintains stable potentials at ca. -0.69 V for 40 h with FE(CO)s>91 %. A superatomic electron configuration of 1S 1P 2S 1D has been clarified by DFT computations, and the strong gold-ligand binding and geometric shell closure account for the superior stability of Au .