Charge-State-Dependent Structural Transitions and Aromatic Stabilization in Anionic and Neutral RuSin(n = 7–11) Clusters

Transition metal (TM)-doped silicon clusters represent critical model systems for understanding nanoscale hybridization and stability mechanisms. This study provides a comprehensive analysis of structural evolution, electronic properties, and thermodynamic stability in ruthenium-doped silicon clusters (RuSin̅/0, n = 7-11) through integrated experimental and computational approaches. Anion photoelectron spectroscopy combined with density functional theory (DFT/B3LYP), coupled-cluster theory [CCSD(T)], and bonding analyses (AdNDP, NICS, ACID) reveals charge-state-dependent structural transitions, with full Ru encapsulation emerging at n = 10 for anions and n = 11 for neutrals. Key findings include pronounced odd-even stability oscillations in neutral clusters, σ-aromaticity in neutral RuSi11 via 52 delocalized electrons satisfying Hückel's rule, and charge redistribution mechanisms governed by coordination geometry. The identification of closed-shell electronic configurations and aromatic stabilization in neutral RuSi11, supported by a HOMO-LUMO gap of 2.11 eV and diatropic ring currents, establishes design principles for stable TM-doped semiconductor nanomaterials. These insights advance the rational engineering of cluster-based materials with tailored electronic and magnetic properties.