Two Size Growth Patterns from Au ₂₂ (SR) ₁₈

Size growth is common in nanomaterial synthesis, particularly for gold nanoclusters, yet its mechanism remains poorly understood due to a lack of structural data. In this work, based on the known face-centered cubic structures of Au₂₂(SR)₁₈ and Au₃₂(SR)₂₄, we predicted the configurations of Au₄₂(SR)₃₀ and Au₅₂(SR)₃₆ via structural analysis. Density functional theory investigations of the size growth from Au₂₂(SR)₁₈ to Au₃₂(SR)₂₄, Au₄₂(SR)₃₀, and Au₅₂(SR)₃₆ clusters revealed two distinct pathways: first, a direct aggregation mechanism; and second, a progressive 2e̅ hopping process that transforms 4e̅ Au₂₂(SR)₁₈ through a series of intermediates into 16e̅ Au₅₂(SR)₃₆ clusters. We further identified two structural evolution patterns: one involving the addition of Au₃⁺ or Au₄²⁺ units, and the other proceeding via the fusion of Au₁₃ units. These findings enhance our fundamental understanding of growth in ligand-protected gold nanoclusters and provide a theoretical basis for their atomically precise synthesis.