Molecular Structure of Copper and μ‑Oxodiiron Octafluorocorrole Derivatives: Insights into Ligand Noninnocence

Single-crystal X-ray structures were
obtained for the copper and μ-oxodiiron complexes of 2,3,7,8,12,13,17,18-octafluoro-5,10,15-triphenylcorrole,
hereafter denoted as Cu­[F8TPC] and {Fe­[F8TPC]}2O. A comparison with the crystal structures of other undecasubstituted
Cu corroles, including those with H, Ar, Br, I, and CF3 as β-substituents, showed that the degree of saddling increases
in the order: H ≲ F < Ar ≲ Br ≲ I < CF3. In other words, Cu­[F8TPC] is marginally more
saddled than β-unsubstituted Cu triarylcorroles, but substantially
less saddled than Cu undecaarylcorroles, β-octabromo-meso-triarylcorroles, and β-octaiodo-meso-triarylcorroles, and far less saddled than Cu β-octakis­(trifluoromethyl)-meso-triarylcorroles. As for {Fe­[F8TPC]}2O, the moderate quality of the structure did not allow us
to draw firm conclusions in regard to bond length alternations in
the corrole skeleton and hence also the question of ligand noninnocence.
The Fe–O bond distances, 1.712(8) and 1.724(8), however, are
essentially identical to those observed for {Fe­[TPFPC]}2O, where TPFPC3– is the trianion of 5,10,15-tris­(pentafluorophenyl)­corrole,
suggesting that a partially noninnocent electronic structural description
may be applicable for both compounds.