Sb@Ni 12 @Sb 20 –/+ and Sb@Pd 12 @Sb 20 n Cluster Anions, Where n = +1, −1, −3, −4: Multi-Oxidation-State Clusters of Interpenetrating Platonic Solids

K 5 Sb 4 and K 3 Sb 7 Zintl ion precursors react with Pd(PPh 3 ) 4 in ethylenediamine/toluene/PBu 4 + solutions to give crystals of Sb@Pd 12 @Sb 20 n – /PBu 4 + salts, where n = 3, 4. The clusters are structurally identical in the two charge states, with nearly perfect I h point symmetry, and can be viewed as an Sb@Pd 12 icosahedron centered inside of an Sb 20 dodecahedron. The metric parameters suggest very weak Sb–Sb and Pd–Pd interactions with strong radial Sb–Pd bonds between the Sb 20 and Pd 12 shells. All-electron DFT analysis shows the 3– ion to be diamagnetic with I h symmetry and a 1.33 eV HOMO–LUMO gap, whereas the 4– ion undergoes a Jahn–Teller distortion to an S = 1/2 D 3 d 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@Pd 12 @Sb 20 – ions (negative ion mode) and Sb@Pd 12 @Sb 20 + (positive ion mode) along with series of Sb@Pd 12- y @Sb 20- x –/+ ions. Ni(cyclooctadiene) 2 reacts with K 3 Sb 7 in en/tol/Bu 4 PBr solvent mixtures to give black precipitates of Sb@Ni 12 @Sb 20 n – salts that give similar Sb@Ni 12 @Sb 20 –/+ parent ions and Sb@Ni 12- y @Sb 20- x –/+ degradation series in the respective LDI-TOF MS studies. The solid-state and gas-phase studies of the icosahedral Sb@M 12 @Sb 20 n –/ 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., C 60 n, where n = +1, 0, −1, −2, −3, −4, −5, −6).