The structures and stabilities of 2,2′-diBeX-1,1′-biphenyl (X = H, F, Cl, CN) derivatives and their affinities for F−, Cl−, and CN−
were theoretically investigated using a B3LYP/6–311 + G(3df,2p)//B3LYP/6–31 + G(d,p) model. The results obtained show that
the 2,2′-diBeX-1,1′-biphenyl derivatives (X = H, F, Cl, CN) exhibit very high F−, Cl−, and CN− affinities, albeit lower than those
reported before for their 1,8-diBeX-naphthalene analogs, in spite of the fact that the biphenyl derivatives are more flexible than
their naphthalene counterparts. Nevertheless, some of the biphenyl derivatives investigated are predicted to have anion affinities
larger than those measured for SbF5, which is considered one of the strongest anion capturers. Therefore, although weaker than
their naphthalene analogs, the 2,2′-diBeX-1,1′-biphenyl derivatives can still be considered powerful anion sponges. This study
supports the idea that compounds containing –BeX groups in chelating positions behave as anion sponges due to the electrondeficient nature and consequently high intrinsic Lewis acidity of these groups.

• Are beryllium-containing biphenyl derivatives efficient anion sponges?