Synthesis and Molecular Structure of a Copper Octaiodocorrole

Although rather delicate on account
of their propensity to undergo
deiodination, β-octaiodoporphyrinoids are of considerable interest
as potential precursors to novel β-octasubstituted macrocycles.
Presented herein are early results of our efforts to synthesize β-octaiodocorrole
derivatives. Oxidative condensation of 3,4-diiodopyrrole and aromatic
aldehydes failed to yield free-base octaiodocorroles. Treatment of
copper meso-tris­(p-cyanophenyl)­corrole
with N-iodosuccinimide and trifluoroacetic acid over
several hours, however, yielded the desired β-octaiodinated
product in ∼22% yield. Single-crystal X-ray structure determination
of the product revealed a strongly saddled corrole macrocycle with
metrical parameters very close to those of analogous Cu octabromocorrole
complexes. The compound was also found to exhibit an exceptionally
red-shifted Soret maximum (464 nm in dichloromethane), underscoring
the remarkable electronic effect of β-octaiodo substitution.