Alkynyl-Protected Bimetallic Nanoclusters with a Hybrid Mackay Icosahedral Ag42Cu12Cl Kernel and an Octahedral Ag22Cu12 Kernel.

A facile strategy that directly reducing alkynyl-silver precursors and copper salts for the synthesis of bimetallic nanoclusters using weak reducing agent Ph2SiH2 is demonstrated. Two alkynyl-protected concentric-shell nanoclusters, (Ph4P)2[Ag22Cu12(C≡CR)28] and (Ph4P)3[Ag42Cu12Cl(C≡CR)36] (Ag22Cu12 and Ag42Cu12Cl, 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 Ag42Cu12Cl, which is icosahedral M54Cl 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.