Chemical bonding between thorium and novel BN nanomaterials

We study the nature of chemical bonding of the thorium atom with novel BN-based nanomaterials: fullerenes B30N30, B12N8, B8N12, and the BN analog of coronene-B12N12H12, used as a representative molecular fragment of the two dimensional hexagonal BN-sheet. Our ab initio calculations are performed within the dispersion-corrected density functional approach with a hybrid exchange-correlation potential. The smallest 20-atom BN-fullerenes B12N8, B8N12 proposed by us are shown to be stable and should be observable experimentally. Thorium is found at the center of these structures pushing the outer shell of atoms farther away. The shape of the B12N8-cage in Th@B12N8 is conserved, while the shape of the B8N12 molecule in Th@B8N12 is largely deformed. The initially planar structure of B12N12H12 in the presence of thorium becomes corrugated, demonstrating pronounced off-plane displacements under the thorium atom. Other four-valent metals (Ti, Zr, and Hf) also cause off-plane displacements of B and N atoms albeit to a much smaller scale. In the 60-atom fullerene B30N30, which is the BN analog of C-60, two conformations of Th@B30N30 are found: one is with thorium facing the hexagon with one B-B and one N-N covalent bonds and a second, lying 0.79 eV higher, with thorium close to the center of pentagon with one B-B covalent bond. Published under an exclusive license by AIP Publishing.