Abstract
[Au(24)Pt(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, [Au(24)Pt(TBBT)(12)(TDT)(3)](0) (TBBT = 4-tert-butylbenzenethiolate; TDT = thiodithiolate) and [Au(24)Pt(TBBT)(12)(PDT)(3)](0) (PDT = 1,3-propanedithiolate), by exchanging all the ligands of [Au(24)Pt(PET)(18)](0) (PET = 2-phenylethanethiolate) with mono- or dithiolates. Although [Au(24)Pt(TBBT)(12)(TDT)(3)](0) was synthesized serendipitously, a similar cluster, [Au(24)Pt(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 [Au(24)Pt(TBBT)(12)(TDT)(3)](0) and [Au(24)Pt(TBBT)(12)(PDT)(3)](0) were different from those in [Au(24)Pt(C6)(18)](0), [Au(24)Pt(PET)(18)](0), and [Au(24)Pt(TBBT)(18)](0), and these subtle differences were reflected in the geometric and electronic structures as well as the HER activities of [Au(24)Pt(TBBT)(12)(TDT)(3)](0) and [Au(24)Pt(TBBT)(12)(PDT)(3)](0). Accordingly, the HER activities of products [Au(24)Pt(TBBT)(12)(TDT)(3)](0) and [Au(24)Pt(TBBT)(12)(PDT)(3)](0) were, respectively, 3.5 and 4.9 times higher than those of [Au(24)Pt(C6)(18)](0) and [Au(24)Pt(TBBT)(18)](0).