Hydride Doping Effects on the Structure and Properties of Eight-Electron Rh/Ag Superatoms: The [RhHx@Ag21–x{S2P(OnPr)2}12] (x= 0–2) Series

Three hitherto unknown eight-electron rhodium/silver alloy nanoclusters, [RhAg21{S2P(OnPr)2}12] (1), [RhHAg20{S2P(OnPr)2}12] (2), and [RhH2Ag19{S2P(OnPr)2}12] (3), have been isolated and fully characterized. Cluster 1contains a regular Rh@Ag12icosahedral core, whereas 2and 3exhibit distorted RhH@Ag12and RhH2@Ag12icosahedral cores. The single-crystal neutron structure of 2located the encapsulated hydride at the center of an enlarged RhAg3tetrahedron. A similar position was found by neutron diffraction for one of the hydrides in 3, whereas the other hydride is trigonally coordinated to Rh and an elongated Ag–Ag edge. The solid-state structures of 1–3possess C1symmetry due to the asymmetric arrangement of the surrounding capping Ag atoms. Our investigation shows that the insertion of one hydride dopant provokes the elimination of one capping silver atom on the cluster surface, resulting in the general formula [RhHx@Ag21–x{S2P(OnPr)2}12] (x= 0–2), which maintains the same number of cluster electrons as well as neutral charge. Clusters 1–3exhibit an intense emission band in the NIR region. Contrarily to their PdAg21and PdHAg20relatives, the 4d orbitals of the encapsulated heterometal are somewhat involved in the optical processes.