Crystal Structures of Two New Gold–Copper Bimetallic Nanoclusters: Cu x Au 25– x (PPh 3 ) 10 (PhC 2 H 4 S) 5 Cl 2 2+ and Cu 3 Au 34 (PPh 3 ) 13 ( t BuPhCH 2 S) 6 S 2 3+

Herein, we report the synthesis and atomic structures of the cluster-assembled Cu x Au 25– x (PPh 3 ) 10 (PhCH 2 CH 2 S) 5 Cl 2 2+ and Cu 3 Au 34 (PPh 3 ) 13 ( t BuPhCH 2 S) 6 S 2 3+ nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The Cu x Au 25– x (PPh 3 ) 10 (PhC 2 H 4 S) 5 Cl 2 2+ NC was assembled by two icosahedral M 13 via a vertex-sharing mode. The Cu atom partially occupies the top and waist sites and is monocoordinated with chlorine or thiol ligands. Meanwhile, the Cu 3 Au 34 (PPh 3 ) 13 ( t BuPhCH 2 S) 6 S 2 3+ NC can be described as three 13-atom icosahedra sharing three vertexes in a cyclic fashion. The three Cu atoms all occupy the internal positions of the cluster core. What is more important is that all three Cu atoms in Cu 3 Au 34 are monocoordinated by the bare S atoms. The absorption spectra of the as-synthesized bimetallic NCs reveal that the additional metal doping and different cluster assemblies affect the electronic structure of the monometallic NCs.