Tailoring Titanium Carbide Clusters for New Materials: from Met-Cars to Carbon-Doped Superatoms.

Tailoring materials with prescribed properties and regular structures is a critical and challenging research topic. Early transition metals were found to form supermagic M 8 C 12 metallocarbohedrenes (Met-Cars); however, stable metal carbides are not limited to this common stoichiometry. Utilizing self-developed deep-ultraviolet laser ionization mass spectrometry, here, we report a strategy to generate new titanium carbides by reacting pure Ti n clusters with acetylene. Interestingly, two products corresponding to Ti 17 C 2 and Ti 19 C 10 exhibit superior abundances in addition to the Ti 8 C 12 Met-Cars. Using global-minimum search, the structures of Ti 17 C 2 and Ti 19 C 10 are determined to be an ellipsoidal D 4d and a rod-shaped D 5h geometry, respectively, both with carbon-capped Ti 4 C moieties and superatomic features. We illustrate the electronic structures and bonding nature in these carbon-doped superatoms concerning their enhanced stability and local aromaticity, shedding light on a new class of metal-carbide nanomaterials with atomic precision.