Boron: even weirder than you thought

High Pressure Yields Novel Single-element Boron ‘Compound’

How can an element be ionic? Classical chemistry textbooks indicate that charge transfer occurs when atoms have different electronegativities and this automatically disqualifies pure elements as possible ionic phases. Boron finds a surprising solution to this problem – its new structure contains two very different types of nanoclusters, B12 icosahedra (blue in the figure above) and B2 dumbbells (orange in the figure above). The electronic structures of these two clusters are very different – in fact, the dependence of electronic properties on the size of the cluster is well known and is the main idea of nanotechnology. Electronegativities of the B12 icosahedra and B2 pairs are different, and this causes charge redistribution and the emergence of partial ionicity in this elemental structure.