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 M₈C₁₂ 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 clusters with acetylene. Interestingly, two products corresponding to Ti₁₇C₂ and Ti₁₉C₁₀ exhibit superior abundances in addition to the Ti₈C₁₂ Met-Cars. Using global-minimum search, the structures of Ti₁₇C₂ and Ti₁₉C₁₀ are determined to be an ellipsoidal D_4d and a rod-shaped D_5h geometry, respectively, both with carbon-capped Ti₄C 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.