The enigma of Au21(SC2H4Ph)14 nanocluster: a synthetic challenge

Recent investigations into atomically precise gold clusters show that not all magic-numbered clusters can be readily obtained through conventional synthetic routes. For example, Au-21(SR)(14), a magic-numbered cluster, was only obtained as a minor product from a mixture of clusters but was never synthesized in pure form using a single-step synthetic approach. We have made several attempts, albeit without any success, using a variety of approaches to synthesize Au-21(SR)(14), clusters in a single step. We show in this communication that synthetic failure is not likely due to electronic instabilities based on computational investigation of its electronic structure. Our DFT calculations show that the optimized cluster consists of a center Au-13 core cluster capped by two Au-2(SCH2CH3)(3) fragments and four Au(SCH2CH3)(2) fragments and is energetically stable. The findings reported here should give more confidence for the synthetic chemists to successfully synthesize Au-21(SR)(14) in the near future.