Aluminium shows unprecedented selectivity for breaking toughest bond

In a first for organometallic reactivity, aluminium has been found to selectively break biphenylene’s toughest carbon–carbon while leaving several weaker bonds intact.

Biphenylene consists of two benzene rings joined together by a pair of bonds, which creates a four-membered ring between them. This central ring is antiaromatic and, because it is so small, under a lot of geometric strain, making its bonds doubly weak and very reactive. In every bond-breaking reaction described so far, an organometallic reagent attacks the central ring and leaves the adjacent benzene rings intact.