Superatomic S(2) silver clusters stabilized by a thiolate-phosphine monolayer: insight into electronic and optical properties of Ag14(SC6H3F2)12(PPh3)8 and Ag16(SC6H3F2)14(DPPE)4

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 118; no. 37; pp. 8351 - 8355
• Main Authors: Gell, Lars, Lehtovaara, Lauri, Häkkinen, Hannu
• Format: Journal Article
• Language: English
• Published: United States 18.09.2014
• ISSN: 1520-5215
• DOI: 10.1021/jp501185q

The electronic structure of two recently crystallographically solved, thiolate-phosphine protected silver clusters Ag14 and Ag16 are analyzed via density functional theory (DFT) and their optical excitations are analyzed from time-dependent DFT perturbation theory. Both clusters can be characterized as having the S(2) free-electron configuration in the metal core, which is the first time such a configuration is confirmed for structurally known ligand-protected noble metal clusters. However, their different core shapes and ligand layer induce significantly different optical spectra. Performance of gradient-corrected DFT functionals is discussed and it is shown that the asymptotically correct Leeuwen-Baerends LB94 functional reproduces the optical spectrum of Ag14 in a good agreement with experiment. Choice of the functional becomes important for clusters where the optical transitions are dominated by the electron-rich ligand layer.