Triangular Au₃ and tetrahedral Au₄ are key structural units in the face-centered cubic gold core of thiolate-protected gold nanoclusters. Understanding their stacking arrangements is essential for elucidating the growth mechanisms of these gold cores. In this study, we design two new isomers of Au₂₉(SR)₁₉ nanoclusters via deliberately adjusting the stacking pattern of Au₃ and Au₄ based on the grand unified model and ring model to show preferable packing arrangements. Among the experimental isomer and the two newly constructed isomers of Au₂₉(SR)₁₉, the Au₃ and Au₄ units display three distinct stacking arrangements: completely independent Au₃; Au₃ sharing a vertex with one Au₄; and Au₃ sharing vertices with two Au₄. Density functional theory calculations reveal that the isomer with a completely independent Au₃ unit owns the lower relative energy, which suggests that forming independent Au₃ in thiolate-protected gold nanoclusters is relatively straightforward, while achieving alternative stacking configurations with Au₃ and Au₄ is more challenging, aligning with experimental observations. This study provides a theoretical foundation for understanding the stacking arrangements between triangular Au₃ and tetrahedral Au₄ units, offering valuable insights for designing ligand-protected gold nanoclusters featuring triangular Au₃ units.

中文翻译：

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硫酸盐保护金纳米团簇中三角形 Au3 和四面体 Au4 单元的堆叠构型：结构稳定性和生长机制洞察


三角形 Au₃ 和四面体 Au₄ 是硫酸盐保护金纳米团簇的面心立方金核心中的关键结构单元。了解它们的堆叠安排对于阐明这些金芯的生长机制至关重要。在本研究中，我们通过在大统一模型和环模型的基础上有意调整 Au₃ 和 Au₄ 的堆叠模式，设计了两种新的 Au₂₉（SR）₁₉ 纳米团簇异构体，以显示更优的堆积排列。在实验异构体和两种新构建的 Au₂₉（SR）₁₉ 异构体中，Au₃ 和 Au₄ 单元表现出三种不同的堆叠排列：完全独立的 Au₃;Au₃ 与 1 个 Au₄ 共享一个顶点;Au₃ 与两个 Au₄ 共享顶点。密度泛函理论计算表明，具有完全独立的 Au₃ 单元的异构体拥有较低的相对能量，这表明在硫酸盐保护的金纳米簇中形成独立的 Au₃ 相对简单，同时使用 Au₃ 和 Au₄ 实现替代堆叠配置更具挑战性，与实验观察结果一致。本研究为理解三角形 Au₃ 和四面体 Au₄ 单元之间的堆叠排列提供了理论基础，为设计具有三角形 Au₃ 单元的配体保护金纳米团簇提供了有价值的见解。