Hierarchy of bond stiffnesses within icosahedral-based gold clusters protected by thiolates

• Published in: Nature communications 2016-01, Vol.7 (1), p.10414-10414, Article 10414
• Main Authors: Yamazoe, Seiji, Takano, Shinjiro, Kurashige, Wataru, Yokoyama, Toshihiko, Nitta, Kiyofumi, Negishi, Yuichi, Tsukuda, Tatsuya
• Format: Article
• Language: English
• Subjects: 639/638/263/915; 639/638/440; 639/925; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10414

Unique thermal properties of metal clusters are believed to originate from the hierarchy of the bonding. However, an atomic-level understanding of how the bond stiffnesses are affected by the atomic packing of a metal cluster and the interfacial structure with the surrounding environment has not been attained to date. Here we elucidate the hierarchy in the bond stiffness in thiolate-protected, icosahedral-based gold clusters Au 25 (SC 2 H 4 Ph) 18 , Au 38 (SC 2 H 4 Ph) 24 and Au 144 (SC 2 H 4 Ph) 60 by analysing Au L 3 -edge extended X-ray absorption fine structure data. The Au–Au bonds have different stiffnesses depending on their lengths. The long Au–Au bonds, which are more flexible than those in the bulk metal, are located at the icosahedral-based gold core surface. The short Au–Au bonds, which are stiffer than those in the bulk metal, are mainly distributed along the radial direction and form a cyclic structural backbone with the rigid Au–SR oligomers. The hierarchy of bond stiffness may contribute to the thermal properties of metal clusters. Here, the authors use X-ray absorption spectroscopy to study the stiffness of the gold–gold and gold–sulfur bonds in a series of thiolate-protected, icosahedral-based gold clusters.