Efficient and Selective Conversion of Phosphine-Protected (MAu₈)²⁺ (M = Pd, Pt) Superatoms to Thiolate-Protected (MAu₁₂)⁶⁺ or Alkynyl-Protected (MAu₁₂)⁴⁺ Superatoms via Hydride Doping

An efficient and selective method was developed for the synthesis of bimetallic clusters, MAu 24 L 18 (M = Pd or Pt; L = thiolates or alkynyls), by the reaction of Au(I)L oligomers with quasi-spherical superatoms [HMAu 8 (PPh 3 ) 8 ] + activated by hydride doping. This hydride-mediated conversion afforded previously known clusters MAu 24 (SC 2 H 4 Ph) 18 having an icosahedral (M@Au 12 ) 6+ core at ∼200 mg scale, with a yield of >50%, and was successfully applied to a variety of primary thiols with good yields. Although the application to secondary and tertiary thiolates was limited, the conversion produced the novel cluster [PdAu 23 (ScC 6 H 11 ) 17 ] 0 having a poorly symmetrical, flattened (Pd@Au 12 ) 6+ core. The conversion produced the new alkynyl-protected clusters [MAu 24 (C≡CAr F ) 18 ] 2– (Ar F = 3,5-(CF 3 ) 2 C 6 H 3 ) having an icosahedral (M@Au 12 ) 4+ core, with a yield of >50%. The larger number of valence electrons in the M@Au 12 core protected by alkynyls is ascribed to an increase in attractive potential of the M@Au 12 core owing to the stronger electron-withdrawing nature of alkynyls than thiolates. This simple and versatile bottom-up approach will provide an opportunity to synthesize a variety of superatoms on a large scale for the promotion of materials science based on superatoms as building units.