Interpenetrating As 20 Fullerene and Ni 12 Icosahedra in the Onion-Skin [As@Ni 12 @As 20 ] Ion

Abstract
The [As@Ni12@As20]3– ion was prepared from As73– and Ni(COD)2 in ethylenediamine solutions and isolated as the Bu4P+ salt (As, arsenic; Ni, nickel; COD, cyclooctadiene; Bu, butyl; P, phosphorus). The anion contains an icosahedral [Ni1212-As)]3– fragment that resides at the center of an As20 dodecahedral (fullerene) cage to give an onion-skin–like [As@Ni12@As20]3– cluster with Ih 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@Ni12@As20]3– ion sequentiallyloses all 21 As atoms to form a series of Ni12As21–x clusters where 0 ≤ x ≤ 21, inclusively.