Synthetic metal-oxide films, nanoparticles, clusters, etc. are excellent for catalyzing, electro-catalyzing, and/or photo-catalyzing oxidation reactions. Of these compounds, polyoxometalates (POMs) are of particular interest to us. They are a special class of metal (e.g., V V , Mo V , Nb V , Ta V , Mo VI , and W VI ) oxide polyanion clusters bridged by oxygen atoms that form well-defined cluster frameworks with adjustable structures and tunable compositions. An enormous variety of well-characterized polyoxometalates exists and many of these can catalyze oxidation reactions, but, they often fall short as catalysts for reduction reactions. In principle, one-to-one sulfur-for-oxygen analogues of POMs, i.e. polythiometalates (PTMs), ought to be synthetically accessible. In practice, the literature is sparse if one ventures beyond tetranuclear transition-metal complexes into the realm of Anderson (seven metal ions), Keggin (twelve metal ions), Dawson (eighteen metal ions) or larger and similarly well-defined, clusters. Nevertheless, synthetic access to capping-ligand-free, sulfur-based analogues of POMs could open-up new reductive catalytic chemistry.