Superatomic Ligand-Field Splitting in Ligated Gold Nanoclusters

Gold nanoclusters are attractive
because of their electronic and
optical properties. Many theoretical models have been proposed to
explain their electronic structures through an electron-counting approach.
However, subtle features may not be well explained by electron-counting
rules. In this work, we have discovered a unique example of ligand-controlled
skeletal bonding in two recently reported gold nanoclusters with very
similar compositions and geometries. We have shown that the superatomic
orbitals of the common kernel of the two clusters undergo different
ligand-field splitting because of the different ligand-field strengths
in the two clusters. Such a difference is clearly revealed by constructing
the Jellium orbitals via an orbital alignment process, and a subsequent
localization of the Jellium orbitals allows us to obtain localized
bonding models. Finally, on the basis of localized bonding models,
we predict the existence of a ligated gold cluster with a [Au32]4+ kernel.