Aqueous Bismuth Titanium-Oxo Sulfate Cluster Speciation and Crystallization

Inorganic aqueous metal-oxo clusters are both functional molecular metal oxides and intermediates to understand metal oxide growth from water. There has been a recent surge in discovery of aqueous Ti-oxo clusters but without extensive solution characterization. We use small-angle and total X-ray scattering, dynamic light scattering, transmission electron microscopy, and a single-crystal X-ray structure to show that heterometals such as bismuth stabilize labile Ti-oxo sulfate clusters in aqueous solution. [Ti22Bi7O41-(OH)(OH2)(30)(SO4)(12)](2+) features edge-sharing between the Ti and Bi polyhedra, in contrast to the dominant corner-linking of Ti-oxo clusters. Bi stabilizes the Ti-polyhedra, which are synergistically stabilized by the bidentate sulfates. Gained stability and potential functionality from heterometals is an incentive to develop more broadly the landscape of heterometallic Ti-oxo clusters.