Carboranes, Anti‐Crowns, and Big Wheels

The supramolecular chemistry of boron–carbon clusters has received significant new impulses from two old hands at boron chemistry: Hawthorne et al. reported in a series of papers on “mercuracarborands”, macrocycles from three or four C 2 B 10 carboranes linked by an equal number of Hg atoms, whose complexation can be considered as that of an anti‐crown (that is, a crown compound with reversed charge distribution); Wade et al. (see this issue p.1328) have achieved the preparation of a macrocycle, in which three meta ‐phenylene and three meta ‐carboranediyl units alternate. This macrocycle promises interesting chemistry not only as an unusual host, but also as a starting material for novel metal complexes.