title: A hollow tetrahedral cage of hexadecagold dianion provides a robust backbone for a tuneable sub-nanometer oxidation and reduction agent via endohedral doping.
abstract: We show, via density functional theory calculations, that dianionic Au16(2-) cluster has a stable, hollow, Td symmetric cage structure, stabilized by 18 delocalized valence electrons. The cage maintains its robust geometry, with a minor Jahn-Teller deformation, over several charge states (q = -1,0,+1), forming spin doublet, triplet and quadruplet states according to the Hund's rules. Endohedral doping of the Au16 cage by Al or Si yields a geometrically robust, tuneable oxidation and reduction agent. Si@Au16 is a magic species with 20 delocalized electrons. We calculate a significant binding energy for the anionic Si@Au16/O2- complex and show that the adsorbed O2 is activated to a superoxo-species, a result which is at variance with the experimentally well-documented inertness of Au16- anion towards oxygen uptake.
authors.affiliation: Department of Physics, Nanoscience Center (NSC), University of Jyväskylä, Finland.
authors.forename: Michael
authors.initials: M
authors.lastname: Walter
authors.forename: Hannu
authors.initials: H
authors.lastname: Häkkinen