The [As@Ni ₁₂ @As ₂₀ ] ^3– ion was prepared from As ₇ ^3– and Ni(COD) ₂ in ethylenediamine solutions and isolated as the Bu ₄ P ⁺ salt (As, arsenic; Ni, nickel; COD, cyclooctadiene; Bu, butyl; P, phosphorus). The anion contains an icosahedral [Ni ₁₂ (μ ₁₂ -As)] ^3– fragment that resides at the center of an As ₂₀ dodecahedral (fullerene) cage to give an onion-skin–like [As@Ni ₁₂ @As ₂₀ ] ^3– cluster with I _h point symmetry. The icosahedron and pentagonal dodecahedron are reciprocal platonic solids, and the 32 surface atoms form a dimpled geodesic sphere composed of 60 triangular faces. In the gas phase, the [As@Ni ₁₂ @As ₂₀ ] ^3– ion sequentiallyloses all 21 As atoms to form a series of Ni ₁₂ As _{21– x} clusters where 0 ≤ x ≤ 21, inclusively.

Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single [thgr]-Al2O3 supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single [thgr]-Al2O3 supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Pt atoms are as active as fully formed platinum particles. Thus, the overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms.