Ligand effects on the stability of thiol-stabilized gold nanoclusters: Au₂₅(SR)₁₈^-, Au₃₈(SR)₂₄, and Au₁₀₂(SR)₄₄

We have studied the electrochemical and thermodynamic stability of Au ₂₅(SR)₁₈^-, Au₃₈(SR)₂₄, and Au₁₀₂(SR)₄₄, R = CH₃, C₆H ₁₃, CH₂CH₂Ph, Ph, PhF, and PhCOOH, in order to examine ligand effects on the stability of thiol-stabilized gold nanoclusters, Au_m(SR)_n. Aliphatic thiols, in general, have higher electrochemical and thermodynamic stability than aromatic thiols, and the -SCH₂CH₂Ph thiol is particularly appealing because of its high electrochemical and thermodynamic stability. The stabilization of Au _m by nSR for Au_m(SR)_n can be rationalized by the stabilization of an Au atom by an SR for the simple molecule AuSR, regardless of interligand interaction and system size and shape. Thiol moieties play a strong role in the electron oxidation and reduction of Au _m(SR)_n. Accounting for the characteristics of thiol ligands is essential for understanding the electronic and thermodynamic stability of thiol-stabilized gold nanoclusters.