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, MAu24L18 (M = Pd or Pt; L = thiolates or alkynyls), by the reaction of Au­(I)­L oligomers with quasi-spherical superatoms [HMAu8(PPh3)8]+ activated by hydride doping. This hydride-mediated conversion afforded previously known clusters MAu24(SC2H4Ph)18 having an icosahedral (M@Au12)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 [PdAu23(ScC6H11)17]0 having a poorly symmetrical, flattened (Pd@Au12)6+ core. The conversion produced the new alkynyl-protected clusters [MAu24(CCArF)18]2– (ArF = 3,5-(CF3)2C6H3) having an icosahedral (M@Au12)4+ core, with a yield of >50%. The larger number of valence electrons in the M@Au12 core protected by alkynyls is ascribed to an increase in attractive potential of the M@Au12 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.