Sb@Ni₁₂@Sb₂₀^–/+ and Sb@Pd₁₂@Sb₂₀^<i>n</i> Cluster Anions, Where <i>n</i> = +1, −1, −3, −4: Multi-Oxidation-State Clusters of Interpenetrating Platonic Solids

K5Sb4 and K3Sb7 Zintl ion precursors react with Pd­(PPh3)4 in ethylene­diamine/toluene/PBu4+ solutions to give crystals of Sb@Pd12@Sb20n–/PBu4+ salts, where n = 3, 4. The clusters are structurally identical in the two charge states, with nearly perfect Ih point symmetry, and can be viewed as an Sb@Pd12 icosahedron centered inside of an Sb20 dodecahedron. The metric parameters suggest very weak Sb–Sb and Pd–Pd interactions with strong radial Sb–Pd bonds between the Sb20 and Pd12 shells. All-electron DFT analysis shows the 3– ion to be diamagnetic with Ih symmetry and a 1.33 eV HOMO–LUMO gap, whereas the 4– ion undergoes a Jahn–Teller distortion to an S = 1/2 D3d structure with a small 0.1 eV gap. The distortion is predicted to be small and is not discernible by crystallography. Laser desorption–ionization time-of-flight mass spectrometry (LDI-TOF MS) studies of the crystalline samples show intense parent Sb@Pd12@Sb20– ions (negative ion mode) and Sb@Pd12@Sb20+ (positive ion mode) along with series of Sb@Pd12‑y@Sb20‑x–/+ ions. Ni­(cyclooctadiene)2 reacts with K3Sb7 in en/tol/Bu4PBr solvent mixtures to give black precipitates of Sb@Ni12@Sb20n– salts that give similar Sb@Ni12@Sb20–/+ parent ions and Sb@Ni12‑y@Sb20‑x–/+ degradation series in the respective LDI-TOF MS studies. The solid-state and gas-phase studies of the icosahedral Sb@M12@Sb20n–/n+ ions show that the clusters can exist in the −4, −3, −1, +1 (M = Pd) and +1, −1 (M = Ni) oxidation states. These multiple-charge-state clusters are reminiscent of redox-active fullerenes (e.g., C60n, where n = +1, 0, −1, −2, −3, −4, −5, −6).