The mixing of heteroelements in metal clusters is a powerful approach to generate new physical/chemical properties and functions. However, as the kinds of elements increase, control of the chemical composition and geometric structure becomes difficult. We succeeded in the compositionally selective synthesis of phenylethanethiolate-protected trimetallic AuAgPd and AuAgPt clusters, AuAgPd(SCHPh) and AuAgPt(SCHPh). Single-crystal X-ray structural analysis revealed the precise position of each metal element in these metal clusters. Reacting with thiol at an elevated temperature was found to be important to direct the metal elements to the most stable positions. The electronic structures of these trimetallic clusters become more discretized than those of the related bimetallic clusters due to orbital splitting.

2-Phenylethanethiolate (PET) and 4-tert-butylbenzenethiolate (TBBT) are the most frequently used ligands in the study of thiolate (SR)-protected metal clusters. However, the effect of difference in the functional group between these ligands on the fundamental properties of the clusters has not been clarified. We synthesized [Au 24 Pt(TBBT) 18 ] 0 , which has the same number of metal atoms, number of ligands, and framework structure as [Au 24 Pt(PET) 18 ] 0 , by replacing ligands of [Au 24 Pt(PET) 18 ] 0 with TBBT. It was found that this ligand exchange is reversible unlike the case of other metal-core clusters. A comparison of the geometrical/electronic structure and stability of the clusters between [Au 24 Pt(PET) 18 ] 0 and [Au 24 Pt(TBBT) 18 ] 0 revealed three things with regard to the effect of ligand change from PET to TBBT on [Au 24 Pt(SR) 18 ] 0 : (1) the induction of metal-core contraction and Au-S bond elongation, (2) no substantial effect on the HOMO-LUMO gap but a clear difference in optical absorption in the visible region, and (3) the decrease of stabilities against degradation in solution and under laser irradiation. By using these two clusters as model clusters, it is expected that the effects of the structural difference of ligand functionalgroups on the physical properties and functions of clusters, such as catalytic ability and photoluminescence, would be clarified. † Electronic supplementary information (ESI) available: Bond lengths, peak positions in SWV curves, additional schemes, characterization of a precursor, photograph of TLC and crystal, ESI mass and XPS spectra, HPLC chromatogram, crystal data of the product. CCDC 1944945. For ESI and crystallographic data in CIF or other electronic format see

Recently, platinum (Pt) clusters have attracted attention as miniaturized fuelcell redox catalysts. Although Pt clusters can be synthesized with atomic accuracy using carbon monoxide (CO) and phosphine as ligands, few studies have examined their electronic structure. We obtained experimental information about the electronic structure of these Pt clusters. We precisely synthesized the cationic Pt 17 cluster, [Pt 17 (CO) 12 (PPh 3 ) 8 ] n+ (n = 1, 2), protected by CO and triphenylphosphine (PPh 3 ) by a simple method and studied its geometric and electronic structures by single-crystal X-ray structure analysis, X-ray photoelectron spectroscopy, optical absorption spectroscopy, differential pulse voltammetry, and photoluminescence spectroscopy. The results indicated that cationic [Pt 17 (CO) 12 (PPh 3 ) 8 ] n+ (n = 1, 2) has a geometric structure similar to that of previously reported neutral Pt 17 (CO) 12 (PEt 3 ) 8 . The Pt 17 skeleton of Pt 17 (CO) 12 (PPh 3 ) 8 depended on the charge state of the cluster ([Pt 17 (CO) 12 (PPh 3 ) 8 ] + or [Pt 17 (CO) 12 (PPh 3 ) 8 ] 2+ ). [Pt 17 (CO) 12 (PPh 3 ) 8 ] n+ (n = 1, 2) possessed a discretized electronic structure, similar to that of fine gold clusters, and exhibited photoluminescence in the near-infrared region. This research will aid fundamental and applied research on Pt clusters.