X-ray Crystal Structure and Theoretical Analysis of Au25-xAgx(SCH2CH2Ph)18(-) Alloy

• Published in: The journal of physical chemistry letters Vol. 5; no. 3; p. 461
• Main Authors: Kumara, Chanaka, Aikens, Christine M, Dass, Amala
• Format: Journal Article
• Language: English
• Published: United States 06.02.2014
• Subjects: Au25; alloy nanomolecules; gold−silver alloy; monolayer protected clusters
• DOI: 10.1021/jz402441d
• ISSN: 1948-7185

The atomic arrangement of Au and Ag atoms in Au25-xAgx(SR)18 was determined by X-ray crystallography. Ag atoms were selectively incorporated in the 12 vertices of the icosahedral core. The central atom and the metal atoms in the six [-SR-Au-SR-Au-SR-] units were exclusively gold, with 100% Au occupancy. The composition of the crystals determined by X-ray crystallography was Au18.3Ag6.7(SCH2CH2Ph)18. This composition is in reasonable agreement with the composition Au18.8Ag6.2(SCH2CH2Ph)18 measured by electrospray mass spectrometry. The structure can be described in terms of shells as Au1@Au5.3Ag6.7@6×[-SR-Au-SR-Au-SR-]. Density functional theory calculations show that the electronic structure and optical absorption spectra are sensitive to the silver atom arrangement within the nanocluster.