Site-specific doping of silver atoms into a Au25 nanocluster as directed by ligand binding preferences

For the first time site-specific doping of silver into a spherical Au 25 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 D-3 symmetry, in contrast to the I-h Au@Au-12 kernel in the well-known [Au-25(SR)(18)](-) (R = CH2CH2Ph). An interesting feature is the coexistence of [Au-2(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 [Au-25(SR)(18)](-), that is, the HOMO-LUMO transition of Au19Ag6 is optically forbidden due to the P character of the superatomic frontier orbitals.

Automated summary

For the first time, site-specific doping of silver into a spherical Au25 nanocluster has been achieved through a dual-ligand coordination strategy. The cluster has a distorted centered icosahedral core and shows the coexistence of two types of stabilizers.