Super Polycationic Molecular Compounds: Au₁₄₄(SR⁺)₆₀ Clusters

We have recently pioneered per-cationized molecular gold (Au) cluster compounds. Herein, we present a new series of per-cationized Au cluster compounds, Au₁₄₄(SR⁺)₆₀, which is the largest reported compound with the most stable and studied Au clusters. Although it is typically difficult to obtain a single composition of a Au₁₄₄ cluster due to the existence of similar-sized quasi-stable compounds, optimized thermal etching and selective precipitation made strict size focusing into a single Au₁₄₄ composition possible and produced Au₁₄₄(SR⁺)₆₀ with high atomic precision. In positive-mode high-resolution ESI-MS, per-cationized Au₁₄₄(SR⁺)₆₀ clusters with different numbers of PF₆^– counteranions for the +12- to +21-charged states were observed. The Au₁₄₄(SR⁺)₆₀, 60­(+) termini distributed over a spherical surface of radius ∼2.5 nm, presented here, is, to the best of our knowledge, the most polycationic molecular compound reported thus far.