Alkynyl-Protected Bimetallic Nanoclusters with a Hybrid Mackay Icosahedral Ag₄₂ Cu₁₂ Cl Kernel and an Octahedral Ag₂₂...

A facile strategy that directly reduces alkynyl-silver precursors and copper salts for the synthesis of bimetallic nanoclusters using the weak reducing agent Ph₂ SiH₂ is demonstrated. Two alkynyl-protected concentric-shell nanoclusters, (Ph₄ P)₂ [Ag₂₂ Cu₁₂ (C≡CR)₂₈ ] and (Ph₄ P)₃ [Ag₄₂ Cu₁₂ Cl(C≡CR)₃₆ ] (Ag₂₂ Cu₁₂ and Ag₄₂ Cu₁₂ Cl, R=bis(trifluoromethyl)phenyl), were successfully obtained and characterized by single-crystal X-ray diffraction and electro-spray ionization mass spectrometry. For the first time, a hybrid 55-atom two-shell Mackay icosahedron was found in Ag₄₂ Cu₁₂ Cl, which is icosahedral M₅₄ Cl instead of M₅₅ . The incorporation of a chloride in the metal icosahedron contributes to the stability of the cluster from both electronic and geometric aspects. Alkynyl ligands show various binding-modes including linear "RC≡C-Cu-C≡CR" staple motifs.