Gold-Doping of Double-Crown Pd Nanoclusters

Double-crown Ni, Pd, or Pt nanoclusters have attracted extensive interests due to their aesthetic structure and intriguing properties. However, their doping by other metals remains unknown until now. Herein, Pd-4(PET)(8) and Pd-5(PET)(10) (PET: SCH2CH2Ph) were successfully doped with gold and the doped nanoclusters were characterized by using multiple techniques such as mass spectrometry and Xray crystallography. It is revealed that in the doping not one but two gold atoms replace one Pd with the other double-crown structure essentially unchanged, and the gold-doping results in the blue-shift of the maximum visible absorption, the increase of optical energy gap and the reduction of anti-aromaticity of monometal Pd nanoclusters. Importantly, it is found that Au4Pd2(PET)(8) nanocluster bears chirality originating from not only the helixed Au4Pd2S8 framework, but also unanimous R or S configuration of sulfur atoms in the enantiomer. For the latter chirality origin, it was not previously reported or proposed. Au4Pd2(PET)(8) reported here also represents the smallest chiral bimetal nanocluster so far to the best of our knowledge. This work advances one step toward both the tailoring of group 10 metal nanoclusters by doping and the understanding of chirality origin for metal nanoclusters.