Synthesis and characterization of a modified “picket fence” porphyrin complex – stronger π bonding interactions between Fe(ii) and axial ligands†
A new, modified “picket fence” porphyrin is synthesized and its bis(imidazole)-ligated iron(II) derivative [Fe(MbenTpivPP)(1-MeIm)2] is investigated. X-ray structure determinations demonstrate that [Fe(MbenTpivPP)(1-MeIm)2] has structural features of a near planar porphyrin plane, a relative perpendicular ligand orientation, and one unusually large absolute ligand orientation (φ). The combination of these features leads to a new type of species that is different from previously reported analogues. Further structural examination reveals a strong correlation between the mutual ligand orientations (θ) and the axial Fe–NIm bond distances, which is detailed for the first time. Mössbauer spectroscopic characterization shows that the low spin derivative has a quadrupole splitting of 0.99 mm s−1 at 100 K.