Unique Axial Imidazole Geometries of Fully Halogenated
Iron(II) Porphyrin Complexes: Crystal Structures and Mössbauer
Spectroscopic Studies
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Abstract
The
synthesis and characterization of several electron-poor iron(II)
porphyrin (FeTFPPBr<sub>8</sub>) complexes with axial imidazole ligands
are reported. The single-crystal X-ray structures have been studied
by a combination of crystal packing and Hirshfeld surface calculations,
which explained the unusual axial-ligand geometries, e.g., the strong
tilt of the Fe–N<sub>Im</sub> bonds and the imidazole planes.
The six-coordinate [Fe(TFPPBr<sub>8</sub>)(1-MeIm)<sub>2</sub>] was
studied by multiple-temperature solid-state Mössbauer spectroscopy,
which suggested that it is a low-spin complex with δ ∼
0.32–0.38 mm/s and Δ<i>E</i><sub>Q</sub> ∼
1.0 mm/s
