Surface modifications of eight-electron palladium silver superatomic alloys

Atomically precise thiolate-protected coinage metal nanoclusters and their alloys are far more numerous than their selenium congeners, the synthesis of which remains extremely challenging. Herein, we report the synthesis of a series of atomically defined dithiophosph(in)ate protected eight-electron superatomic palladium silver nanoalloys [PdAg20{S2PR2}(12)], 2a-c (where R = (OPr)-Pr-i, a; (OBu)-Bu-i, b; Ph, c) via ligand exchange and/or co-reduction methods. The ligand exchange reaction on [PdAg20{S2P((OPr)-Pr-n)(2)}(12)], 1, with [NH4{Se2PR2}(12)] (where R = (OPr)-Pr-i, or (OPr)-Pr-n) leads to the formation of [PdAg20{Se2P((OPr)-Pr-i)(2)}(12)] (3) and [PdAg20{Se2P((OPr)-Pr-n)(2)}(12)] (4), respectively. Solid state structures of 2a, 2b, 3 and 4 unravel different PdAg20 metal frameworks from their parent cluster, originating from the different distributions of the eight-capping silver(I) atoms around a Pd@Ag-12 centered icosahedron with C2,D3,Th and T-h symmetries, respectively. Surprisingly ambient temperature crystallization of the reaction product 3 obtained by the ligand exchange reaction on 1 has resulted in the co-crystallization of two isomers in the unit cell with overall T (3a) and C-3 (3b) symmetries, respectively. To our knowledge, this is the first ever characterized isomeric pair among the selenolate-protected NCs. Density functional theory (DFT) studies further rationalize the preferred geometrical isomerism of the PdAg20 core. Atomically and structurally precise silver nanoclusters hold great potential for catalytic and optoelectronic applications. Here, the authors synthesize and characterize a series of atomically defined dithio- and diselenophosphate-protected eight-electron superatomic palladium-doped silver nanoclusters, including an unprecedented pair of selenolate-protected isomers.

Automated summary

This study reports the synthesis and characterization of a series of atomically defined dithio- and diselenophosphate-protected eight-electron superatomic palladium-doped silver nanoclusters, including an unprecedented pair of selenolate-protected isomers. The solid state structures revealed different metal frameworks from the parent cluster due to the distribution of capping silver(I) atoms around a Pd@Ag-12 centered icosahedron with different symmetries. The crystallization of the reaction product led to the co-crystallization of two isomers in the unit cell, a first among selenolate-protected nanoclusters.