Surface modifications of eight-electron palladium silver superatomic alloys
Subrat Kumar Barik, Chih‐Yuan Chen, Tzu‐Hao Chiu, Yu‐Rong Ni, Franck Gam, Isaac Chantrenne, Samia Kahlal, Jean‐Yves Saillard, C. W. Liu
Abstract
Abstract 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 [PdAg 20 {S 2 PR 2 } 12 ], 2a–c (where R = O i Pr, a ; O i Bu, b ; Ph, c ) via ligand exchange and/or co-reduction methods. The ligand exchange reaction on [PdAg 20 {S 2 P(O n Pr) 2 } 12 ], 1 , with [NH 4 {Se 2 PR 2 } 12 ] (where R = O i Pr, or O n Pr) leads to the formation of [PdAg 20 {Se 2 P(O i Pr) 2 } 12 ] ( 3 ) and [PdAg 20 {Se 2 P(O n Pr) 2 } 12 ] ( 4 ), respectively. Solid state structures of 2a, 2b, 3 and 4 unravel different PdAg 20 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 C 2, D 3, T h 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 PdAg 20 core.