Effect of Group-10 Element M (Ni, Pd, Pt) on Electronic Structure of Icosahedral M@Au12 Cores of MAu24L18 (L = Alkynyl, Thiolate)

Heterometal doping into chemically modified gold clusters is a straightforward method to modulate their electronic structure. Although examples exist of alloy clusters containing a series of heterometeal dopants from different groups of the periodic table, it is rare for a complete set of alloy clusters to contain dopants from the same group. In this work, we newly synthesize Ni-doped gold clusters with NiAu24L18 [L = ArFCC– (ArF = 3,5-(CF3)2C6H3), PhC2H4S–] by using hydrogen-containing phosphine-protected NiAu clusters as precursors. The synthesis of the Ni-doped counterpart allows us to compare the geometric and electronic structures of prototypical alloy clusters with a M@Au12 core (M = Ni, Pd, Pt). Single-crystal X-ray diffraction analysis indicates that due to the small atomic radius of Ni, NiAu24L18 has a slightly contracted core than clusters with M = Pd or Pt. Voltammetry and optical absorption spectroscopy suggest that the modified jellium model cannot solely explain the period-dependent doping effect because the Ni@Au12 core contracts. MAu24L18 clusters (L = PhC2H4S–) are paramagnetized by single electron reduction, and their magnetic properties are investigated by using electron spin resonance spectroscopy. This work thus provides a guide for designing gold clusters by heterometal doping within a given group of the periodic table.