Atomically Precise Au24Pt(thiolate)12(dithiolate)3 Nanoclusters with Excellent Electrocatalytic Hydrogen Evolution Reactivity

[Au24Pt(C6)18]0 (C6 = 1-hexanethiolate) is twice as active as commercial Pt nanoparticles in promoting the electrocatalytic hydrogen evolution reaction (HER), thereby attracting attention as new HER catalysts with well-controlled geometric structures. In this study, we succeeded in synthesizing two new Au–Pt alloy nanoclusters, namely, [Au24Pt(TBBT)12(TDT)3]0 (TBBT = 4-tert-butylbenzenethiolate; TDT = thiodithiolate) and [Au24Pt(TBBT)12(PDT)3]0 (PDT = 1,3-propanedithiolate), by exchanging all the ligands of [Au24Pt(PET)18]0 (PET = 2-phenylethanethiolate) with mono- or dithiolates. Although [Au24Pt(TBBT)12(TDT)3]0 was synthesized serendipitously, a similar cluster, [Au24Pt(TBBT)12(PDT)3]0, was subsequently obtained by selecting the appropriate reaction conditions and optimal combination of thiolate and dithiolate ligands. Single crystal X-ray diffraction analyses revealed that the lengths and orientations of −Au(I)–SR–Au(I)– staples in [Au24Pt(TBBT)12(TDT)3]0 and [Au24Pt(TBBT)12(PDT)3]0 were different from those in [Au24Pt(C6)18]0, [Au24Pt(PET)18]0, and [Au24Pt(TBBT)18]0, and these subtle differences were reflected in the geometric and electronic structures as well as the HER activities of [Au24Pt(TBBT)12(TDT)3]0 and [Au24Pt(TBBT)12(PDT)3]0. Accordingly, the HER activities of products [Au24Pt(TBBT)12(TDT)3]0 and [Au24Pt(TBBT)12(PDT)3]0 were, respectively, 3.5 and 4.9 times higher than those of [Au24Pt(C6)18]0 and [Au24Pt(TBBT)18]0.