Iodinated cobalt corroles

Cobalt(III) complexes of selectively β-pyrrole-iodinated corroles were prepared and characterized for the first time. X-ray crystallographic data reveals that the corrole macrocycle remains quite planar despite of the presence of multiple iodine substituents. The redox potentials increase linearly with the number of iodine substituents, much more for reduction than for oxidation, in a similar pattern to that of previously reported gold(III), gallium(III), and aluminum(III) complexes of β-pyrrole-iodinated corroles. Their effect on reduction potential is much larger than what is observed for analogous gallium(III) and aluminum(III) corroles, wherein the chelated element is not redox active. Interestingly, the effect of iodine is similar to that of the much more electronegative halides, which is attributed to a stronger π-back donation by the latter. One advantage of achieving selective iodination, in terms of the number and positioning, is that is provides an entry to further functionalization of the corro...