Molecular Structures of Five-Coordinated Halide Ligated Iron(III) Porphyrin, Porphycene, and Corrphycene Complexes

Molecular structures of 12 porphyrin analogues, FeIII(EtioP)X(1a−1d), FeIII(EtioCn)X(2a−2d), and FeIII(Etio-Pc)X(3a−3d), where X =
F (a), Cl (b), Br (c), and I (d), are determined on the basis of
X-ray crystallography. Combined analyses using Mössbauer, 1H
NMR, and EPR spectroscopy as well as SQUID magnetometry
have revealed that 3d exhibits a quite pure S = 3/2 spin state with
a small amount of an S = 5/2 spin admixture. In contrast, all the
other complexes show the S = 5/2 spin state with a small amount
of the S = 3/2 spin admixture. The structural and spectroscopic
data indicate a strong correlation between the spin states of the
complexes and the core geometries such as Fe−N bond lengths,
cavity areas, and ΔFe values.