Density functional theory (DFT) simulations were also carried out to provide molecular level insights into the structure. As fully sulfided analogues of the Anderson POM are unknown, we started from the structure of Mo7O24 (Figure ) and replaced the central Mo atom with a Co atom and all O atoms with S atoms. We then varied the H and S contents, chemical states of S, and overall cluster charges and performed geometry relaxations in DFT. The structural model of the cluster was evaluated by comparing the dPDF, S:Mo ratios, Mo coordination numbers and Mo oxidation states of all experimental data with computed models. The calculated structures that give the best agreement with experiment are negatively charged. The structure that agrees best with experimental dPDF results comprises terminal SH -, bridging and terminal S 2-, and bridging S2 2-ligands (Figure ). Thus, the arrangement and configuration of the main-group element in the PTM is richer than in the parent POM. Notably, this unique cluster exposes a large fraction of sulfur atoms as edge-sited atoms -a point of direct relevance for envisioned catalytic applications.