[Co2@(Ge17Ni)]4−: the first edge-sharing double-cage endohedral germanide

Abstract

We report here a new double-cage endohedral Ge cluster, [Co₂@(Ge₁₇Ni)]⁴⁻, fused through two [Co@(Ge₉Ni)] moieties with a shared Ni–Ge edge. This ternary Co–Ge–Ni species not only represents the first double-cage example of an 18-vertex Zintl cluster, but also fills in the missing link of the edge fusion model in the double-cage systems.