Borospherene


Borospherene is a cluster molecule containing 40 boron atoms. It is similar to buckminsterfullerene, the "spherical" carbon structure, but with a different symmetry. The discovery of borospherene was announced in July 2014, and is described in the journal Nature Chemistry. Borospherene is the latest in a series of cluster molecules, including buckminsterfullerene, stannaspherene, and plumbaspherene. The newly discovered molecule includes unusual heptagonal faces.

Structure

Borospherene has a unique axis of symmetry, so it is not really "spherical" like buckminsterfullerene. Its symmetry group is D2d. It includes 48 boron triangles between four seven-sided rings and two six-membered rings. There are four sets of eight equivalent boron atoms, and two sets of four equivalent atoms. Each boron atom binds to four or five other boron atoms.
Lai-Sheng Wang, professor of chemistry at Brown University, modeled possible B40 structures on computer. Two forms were predicted – a sheet-like structure and a closed cage. Photoelectron spectroscopy revealed that the substance formed in the laboratory was this cage. The structure of the cage is not perfectly uniform – "Several atoms stick out a bit from the others, making the surface of borospherene somewhat less smooth than a buckyball" according to Wang.