Symmetry Reduction upon Size Mismatch: The Non‐Icosahedral Intermetalloid Cluster [Co@Ge 12 ] 3−

A new complex comprising [Co@Ge 12 ] 3– cluster core was synthesized through the reaction of CoMe(PMe 3 ) 4 and K 4 Ge 9 in ethylenediamine solution. The pseudo‐ D 5d geometry of this cluster can be viewed as structurally derived from an icosahedral cage via Jahn‐Teller effect, leading to notable bonding differences from I h ‐[M@E 12 ] q − clusters (E = Sn, Pb with q = 2, 3). The [Co@Ge 12 ] 3– cluster represents a structural conundrum. On the basis of the geometric considerations it could be viewed as a sandwich complex. However, chemical bonding analysis revealed that there is a direct covalent multicenter bonding between the two pentagons, thus indicating that the structure should be viewed as an elongated icosahedron. Further theoretical calculations on [M@Ge 12 ] 3− (M = Rh, Ir, Mt) indicate that similar compounds of larger‐size metal atoms can drive the complete transformation of [M@Ge 12 ] 3− clusters from icosahedron structure to a sandwich one.