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Abstract The crystal structures of 4 ligand‐rotational isomers of Au₂₅(PET)₁₈are presented. Two new ligand‐rotational isomers are revealed, and two higher‐quality structures (allowing complete solution of the ligand shell) of previously solved Au₂₅(PET)₁₈clusters are also presented. One of the structures lacks an inversion center, making it the first chiral Au₂₅(SR)₁₈structure solved. These structures combined with previously published Au₂₅(SR)₁₈structures enable an analysis of the empirical ligand conformation landscape for Au₂₅(SR)₁₈clusters. This analysis shows that the dihedral angles within the PET ligand are restricted to certain observable values, and also that the dihedral angle values are interdependent, in a manner reminiscent of biomolecule dihedral angles such as those in proteins and DNA. The influence of ligand conformational isomerism on optical and electronic properties was calculated, revealing that the ligand conformations affect the nanocluster absorption spectrum, which potentially provides a way to distinguish between isomers at low temperature. 

Metal-ion-containing soft materials include metallogels, metal-organic frameworks, and coordination polymers. These materials show commercial value in catalysis, hydrogen storage, and electronics. Metal-containing soft materials reported to date are structurally weak, falling short of a Young’s modulus typical of engineering-grade materials. We report herein that inclusion of an antisolvent in metal-thiolate metallogel synthesis results in a colloidal sol, where the colloids comprise amorphous metal-organic complexes. Upon desolvation, the colloids coalesce to form a solid phase that is both gel like and glass like. This solid phase is structurally amorphous, comprises continuous networks similar to organic polymers, and has stiffness observed in polymeric materials with extended structure, yet contains a superstoichiometric amount of metal relative to organic ligand. The solid phase is therefore a rigid, amorphous metal-rich (RAMETRIC) material. Highlighting the rigidity, the Young’s modulus of the gel-phase material is 1,000× greater than metallogels comprised of the same constituent building blocks.