How Do Charge States Affect Ammonia Coordination in Superatomic Niobium Clusters?

Atomically precise metal clusters have garnered significant research attention owing to their distinctive properties, which make them promising for advanced materials and catalytic applications. A fundamental understanding of metal cluster-ligand interactions is crucial for developing efficient cluster-based catalysts and functional materials. In this study, we show that Nb_n ⁺ and Nb_n ^- clusters exhibit charge-dependent reactivity with NH₃, resulting in prominent coordination products including Nb₇(NH₃)₇ ⁺, Nb₇(NH₃)₂ ^-, Nb₈(NH₃)₈ ⁺, and Nb₈(NH₃)₄ ^-. Using DFT calculations, we uncovered the critical role of cluster charge states and Lewis-acid sites in determining reactivity and the formation of complex products. Furthermore, we elucidated the superatom-σ coordination mode and the stability mechanism of these complexes. This study offers new insights into coordination chemistry and provides a foundation for rational design of new materials via metal cluster complexes.