Precise synthesis of platinum and alloy clusters and elucidation of their structures

We report herein new Pt and bi-/tri-metallic alloy clusters. For the Pt clusters, we have precisely synthesized the cationic Pt17 clusters, [Pt17(CO)12(PPh3)8]n+ (n = 1, 2), protected by CO and triphenylphosphine (PPh3) by a simple method. The study on the synthesized clusters revealed that [Pt17(CO)12(PPh3)8]n+ (n = 1, 2) have geometrical structures similar to that of previously reported Pt17(CO)12(PEt3)8 (PEt3 = triethylphosphine) and they [Pt17(CO)12(PPh3)8]n+ (n = 1, 2) possessed discretized electronic structures. For the bimetallic cluster, we have established a method to selectively synthesize hetero-biicosahedral [Au24Pd(PPh3)10(SC2H4Ph)5Cl2]+ (SC2H4Ph = phenylethanethiolate), in which a Pd atom replaces the central Au atom in one icosahedral Au13 core. The theoretical study on the related cluster suggested that [Au24Pd(PPh3)10(SC2H4Ph)5Cl2]+ has dipole moment and is comparatively stable during cluster reduction. For the trimetallic cluster, we succeeded in the compositionally selective synthesis of [Au∼20Ag∼4Pd(SC2H4Ph)18]0 and [Au∼20Ag∼4Pt(SC2H4Ph)18]0. Single crystal X-ray structural analysis revealed the precise position of each metal element in these metal clusters. In this study, it was demonstrated that reacting with thiol at an elevated temperature is important to direct the metal elements to the most stable positions.