Crystal Structures of Two New Gold–Copper Bimetallic Nanoclusters: Cu_<i>x</i>Au_{25–<i>x</i>}(PPh₃)₁₀(PhC₂H₄S)₅Cl₂²⁺ and Cu₃Au₃₄(PPh₃)₁₃(^tBuPhCH₂S)₆S₂³⁺

Herein, we report the synthesis and atomic structures of the cluster-assembled Cu_<i>x</i>­Au_{25–<i>x</i>}­(PPh₃)₁₀­(PhCH₂CH₂S)₅­Cl₂²⁺ and Cu₃­Au₃₄­(PPh₃)₁₃­(^tBuPhCH₂S)₆­S₂³⁺ nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The Cu_<i>x</i>­Au_{25–<i>x</i>}­(PPh₃)₁₀­(PhC₂H₄S)₅­Cl₂²⁺ NC was assembled by two icosahedral M₁₃ 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 Cu₃­Au₃₄­(PPh₃)₁₃­(^tBuPhCH₂S)₆­S₂³⁺ 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 Cu₃Au₃₄ 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