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

Threehitherto unknown eight-electron rhodium/silver alloy nanoclusters,[RhAg21{S2P((OPr)-Pr- n )(2)}(12)] (1), [RhHAg20{S2P((OPr)-Pr- n )(2)}(12)] (2), and [RhH2Ag19{S2P((OPr)-Pr- n )(2)}(12)] (3), have been isolated and fully characterized. Cluster 1 contains a regular Rh@Ag-12 icosahedral core,whereas 2 and 3 exhibit distorted RhH@Ag-12 and RhH2@Ag-12 icosahedral cores. Thesingle-crystal neutron structure of 2 located the encapsulatedhydride at the center of an enlarged RhAg3 tetrahedron.A similar position was found by neutron diffraction for one of thehydrides in 3, whereas the other hydride is trigonallycoordinated to Rh and an elongated Ag-Ag edge. The solid-statestructures of 1-3 possess C (1) symmetry due to the asymmetric arrangementof the surrounding capping Ag atoms. Our investigation shows thatthe insertion of one hydride dopant provokes the elimination of onecapping silver atom on the cluster surface, resulting in the generalformula [RhH x @Ag21-x {S2P((OPr)-Pr- n )(2)}(12)] (x = 0-2), which maintainsthe same number of cluster electrons as well as neutral charge. Clusters 1-3 exhibit an intense emission band inthe NIR region. Contrarily to their PdAg21 and PdHAg20 relatives, the 4d orbitals of the encapsulated heterometalare somewhat involved in the optical processes.