Controlled Shell and Kernel Modifications of Atomically Precise Pd/Ag Superatomic Nanoclusters.

The first 8-electron Pd/Ag superatomic alloys with an interstitial hydride [PdHAg (dtp) ] (dtp=S P(O Pr) ) 1 and [PdHAg (dtp) ] 2 are reported. The targeted addition of a single Ag atom to 1 is achieved by the reaction of one equivalent of trifluoroacetic acid, resulting in the formation of 2 in 55 % yield. Further modification of the shell results in the formation of [PdAg (dtp) ] 3 via an internal redox reaction, with the system retaining an 8-electron superatomic configuration. The interstitial hydride in 1 and 2 contributes its 1s electron to the superatomic electron count and occupies a PdAg tetrahedron. The distributions of isomers corresponding to different dispositions of the outer capping Ag atoms are investigated by multinuclear VT NMR spectroscopy. The emissive state of 3 has a lifetime of 200 μs (λ =448; λ =842), while 1 and 2 are non-emissive. The catalytic reduction of 4-nitrophenol is demonstrated with 1-3 at room temperature.