Site-specific doping of silver atoms into a Au25 nanocluster as directed by ligand binding preferences |
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Authors: | Wan-Qi Shi Zong-Jie Guan Jiao-Jiao Li Xu-Shuang Han Quan-Ming Wang |
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Institution: | Department of Chemistry, Tsinghua University, Beijing 100084 PR China.; Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 PR China |
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Abstract: | For the first time site-specific doping of silver into a spherical Au25 nanocluster has been achieved in Au19Ag6(MeOPhS)17(PPh3)6] (BF4)2 (Au19Ag6) through a dual-ligand coordination strategy. Single crystal X-ray structural analysis shows that the cluster has a distorted centered icosahedral Au@Au6Ag6 core of D3 symmetry, in contrast to the Ih Au@Au12 kernel in the well-known Au25(SR)18]− (R = CH2CH2Ph). An interesting feature is the coexistence of Au2(SPhOMe)3] dimeric staples and P–Au–SPhOMe] semi-staples in the title cluster, due to the incorporation of PPh3. The observation of only one double-charged peak in ESI-TOF-MS confirms the ordered doping of silver atoms. Au19Ag6 is a 6e system showing a distinct absorption spectrum from Au25(SR)18]−, that is, the HOMO–LUMO transition of Au19Ag6 is optically forbidden due to the P character of the superatomic frontier orbitals.For the first time site-specific doping of silver into a spherical Au25 nanocluster has been achieved in Au19Ag6(MeOPhS)17(PPh3)6] (BF4)2. It is a 6e system showing quite a different absorption spectrum from Au25(SR)18]−. |
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