A 2-to-2′ 18-to-18′ doubly linked Ni() norcorrole dimer: an effectively conjugated antiaromatic dyad

The synthesis and properties of a 2-to-2′ 18-to-18′ doubly linked Ni( ii ) norcorrole dimer are described. It adopts a highly planar structure, resulting in effective electronic interactions between the constituent norcorrole units. Nevertheless, each norcorrole unit exhibits substantial antiaromaticity, which stands in sharp contrast to stacked norcorrole dimers. A fused norcorrole dimer has been synthesized in which each norcorrole unit exhibited distinct antiaromaticity.