The 228 valence electron rule for onion-like inorganic fullerenes X1@Y12@Z20 of Ih and Th symmetry

Based on an analysis of the experimentally known 228e- valence electron systems AsNi12As203-, SbNi12Sb203-, SbPd12Sb203-, and SnCu12Sn2012- of Ih symmetry, the new species GeZn12Ge20, KrNi12As20, BrNi12As201-, SeNi12As202-, GeMn12Br20, SeCo12Se206+, and SeFe12Se206- have been designed according to the 228 electron rule introduced in this study for onion-like inorganic fullerenes composed of late main group and transition metal elements. Of these GeZn12Ge20, KrNi12As20, BrNi12As201-, SeNi12As202-, and GeMn12Br20 together with the known AsNi12As203- and its neutral counterpart were investigated at the DFT B3LYP/6-31G(d) level of theory. With one exception they show, in fact, two stable energetic minima of Ih and Th symmetry. Relaxing the symmetry constraints further, e.g. Y12 = {Q6,R6}, additional new neutral species of the general composition Z@Q6R6@Z20 of C5v and C2v symmetry can be formulated, i.e. Z = Se, Q = Fe, R = Mn, following this new building principle, therefore, supporting and inspiring the development of new materials of icosahedral and tetrahedral symmetry.