PNNL

Abstract

We report solution synthesis of the recently discovered tetrahedral Au20 cluster coordinated with eight PPh3 (Ph = Phenyl) ligands. The composition and molecular weight of the Au20 ( PPh3)8 complex were confirmed by the isotopic pattern of its doubly charged cation using high resolution mass spectrometry. Collision-induced dissociation experiment showed that four PPh3 can be easily dissociated from Au20 ( PPh3)8²?, resulting in a highly stable Au20 ( PPh3)4²? molecule. This observation is consistent with the tetrahedral structure, in which the four apex sites are expected to be strongly bound to the PPh3 ligands, and is confirmed by theoretical calculations, which predicted a highly stable Au20 (PH3)4 complex with Au-PH3 bond energies of ~1 eV. The current experimental and theoretical observations suggest that large quantity of ligand-stabilized tetrahedral Au20 can be obtained, opening the door for exploring its anticipated novel chemical, optical, and catalytical properties.