Au₃(μ₃-S)(0e) elementary block: new insights into ligated gold clusters with μ₃-sulfido motifs

An understanding of the structural stability and formation mechanism of ligated gold nanoclusters with triply coordinated μ₃-sulfido (μ₃-S) motifs is important not only for gold chemistry but also for the design of more effective catalysts or drug carriers for various applications. In this article, a new elementary block Au₃(μ₃-S) with zero valence electrons [referred to as Au₃(μ₃-S)(0e)] has been identified, which describes all crystallized ligated gold clusters with μ₃-S motifs, in conjunction with the previously reported Au₃(2e) and Au₄(2e) elementary blocks, in a grand unified model (GUM). This Au₃(μ₃-S)(0e) elementary block has a tripod structure with the S atom bonding to three Au atoms in a μ₃ bridging mode, and can be considered as a μ₃-S atom balancing out the 2e valence electrons of the Au₃(2e) block. Using Au₃(μ₃-S) as a building block, a special group of quasi-fullerene hollow-cage [Au_3n(μ₃-S)_2n]^n- gold(i) μ₃-S clusters are designed, which exhibit high stabilities. In addition, a series of theoretical structures are predicted to be increasingly stable after introducing μ₃-S atoms, based on the crystallized clusters. Overall, the introduction of a Au₃(μ₃-S)(0e) elementary block can help with the understanding of diverse structures of ligated gold clusters with μ₃-S motifs, thereby assisting the rational design of new forms of gold nanoclusters.