All-selenolate-protected eight-electron platinum/silver nanoclusters. Issue 28 (7th July 2021) - Chiu, Tzu-Hao
Abstract : First eight-electron, Pt–Ag superatoms protected by Se-donor ligands are synthesized by ligand replacement reaction. The metal framework of PtAg20 changes from low symmetry ( C 2 ) to high symmetry ( T h ) via rearrangement of five capping silver atoms. Abstract : The first atomically and structurally precise platinum/silver superatoms protected by Se-donor ligands were synthesized in high yield by adopting ligand replacements on [PtAg20 {S2 P(O n Pr)2 }12 ] (3 ) with 12 equiv. of di-alkyl diselenophosph(in)ates. Structures of [PtAg20 {Se2 P(OR)2 }12 ] (R = n Pr (1a ), i Pr (1b )) and [PtAg20 {Se2 P(CH2 CH2 Ph)2 }12 ] (2 ) were accurately determined by single-crystal X-ray diffraction to reveal an eight-electron [Pt@Ag12 ] 4+ icosahedral core embedded within a cube of eight silver(i ) atoms and wrapped into a shell of 12 diselenophosph(in)ates. While the lowest energy absorption band of the Se derivatives is red-shifted to longer wavelengths in comparison with the S analogue, it is blue-shifted in the emission spectra. Density functional theory (DFT) and TD-DFT calculations rationalize the electronic structures as those of eight-electron superatoms, with their HOMO and LUMO being the 1P and 1D levels, respectively. The two UV–visible lowest bands are associated with 1P → 1D metal to metal charge transfer (MMCT) transitions. The blue shift observed for the S analogue results from a larger HOMO–LUMO gap in the case of dithiolate ligands.