borospherene

thumb|° borospherene Borospherene (B40) is an electron-deficient cluster molecule containing 40 boron atoms. It bears similarities to other homoatomic cluster structures such as buckminsterfullerene (C60), stannaspherene, and plumbaspherene, but with a different symmetry. The first experimental evidence for borospherene was reported in July 2014, and is described in the journal Nature Chemistry. The molecule includes unusual hexagonal and heptagonal faces. Despite many calculation-based investigations into its structure and properties, a viable route for the synthesis and isolation of borospherene has yet to be established, and as a consequence it is still relatively poorly understood.

== History == thumb|Quasi-planar lowest-lying isomer of B40− anion (Cs symmetry). thumb|194x194px|Cage-like second-lowest lying isomer of B40− anion (D2d symmetry) In 2014, the first experimental evidence of a homoelemental fullerene-like B40 cluster was reported by Zhai et al., after decades of theoretical investigations into boron cage structures following the discovery of buckminsterfullerene. Anionic B40− clusters were transiently produced by laser vaporisation of a 10B-enriched boron disc target, and studied with photoelectron spectroscopy. Their experimental spectrum corresponded well to a combination of simulated spectra of a sheet-like, quasi-planar global minimum of the B40− anion (Cs symmetry) and its nearly degenerate fullerene-like structural isomer (D2d symmetry). However, the signal in the anion photoelectron spectrum assigned to cage-like B40 represents only a very minor fraction of the overall signal. Formation of cage-like B40, termed borospherene, has not been confirmed independently using any other experimental approach.