The Role of the Anchor Atom in the Ligand of the Monolayer-Protected Au<sub>25</sub>(XR)<sub>18</sub><sup>–</sup> Nanocluster

We present a density functional theory (DFT) investigation on the role of the anchor atom and ligand on the structural, electronic, and optical properties of the anionic Au<sub>25</sub>(XR)<sub>18</sub><sup>–</sup> nanocluster (X = S, Se, Te; R = H, CH<sub>3</sub>, and (CH<sub>2</sub>)<sub>2</sub>Ph). Substituting the anchor atom with other group 16 elements induces subtle changes in the Au–Au and Au–X bond lengths and polarization of the covalent bond. The changes in the electronic structure based on substituting both the anchor and R groups are presented through careful analysis of the density of states and theoretical determined optical spectra. We give a detailed side-by-side comparison into the structural, electronic, and optical properties of Au<sub>25</sub>(XR)<sub>18</sub><sup>–</sup> cluster and further explain the diverse role of ligand substitution.