ABSTRACT
Boron (B) belongs to the group of least abundant chemical elements: Earth crust contains only around 0.001 wt.% B. As for the role of boron in the formation of the various structural phases, it is incommensurably great. Understanding the diversity of boron structures reduces to the electronic structure of an isolated boron atom. In multiatomic networks, by adding an electron, the valence shell conguration peculiar to the free B atom 2s22p transforms at rst in the energetically more favorable conguration 2s22p2, which then tends to most stable one 2s2p3. Thus, boron is a distinct electron acceptor and, consequently, all-boron structures have to be electron decient. This is the reason why all modications of boron exhibit complex, clustered structures. For them, the icosahedron B12 with 12 boron atoms at vertices serves as a main structural motif.
