[Pt17(CO)12(PPh3)8] n+ (n = 1, 2): Synthesis and Geometric and Electronic Structures

Recently, platinum (Pt) clusters have attracted attention as miniaturized fuel-cell 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 Pt17 cluster, [Pt17(CO)12(PPh3)8] n+ (n = 1, 2), protected by CO and triphenylphosphine (PPh3) 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 [Pt17(CO)12(PPh3)8] n+ (n = 1, 2) has a geometric structure similar to that of previously reported neutral Pt17(CO)12(PEt3)8. The Pt17 skeleton of Pt17(CO)12(PPh3)8 depended on the charge state of the cluster ([Pt17(CO)12(PPh3)8]+ or [Pt17(CO)12(PPh3)8]2+). [Pt17(CO)12(PPh3)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.