Iron(II) Bis(imidazole) Derivatives of a Binuclear Porphyrin Model: Crystal Structures and Mössbauer Properties.

A new sterically hindered "picket fence-like" porphyrin with chelates for the second metal atom, H2TImPP (TImPP = meso-tetrakis[α,α,α,α-o-(5-imidazolecarboxylaminophenyl)]porphyrinato), is developed and used in the synthesis of four iron(II) bis(imidazole) derivatives, which are characterized by single crystal X-ray and other spectroscopies. The comprehensive studies on the crystal structures revealed noteworthy features including new axial ligand arrangements, deformed porphyrin planes, and strongly tilted pickets which can be rationalized by analysis of the intra- and intermolecular interactions. Solid-state Mössbauer experiments on [Fe(TImPP)(1-MeIm)2] were conducted at several temperatures from 295 to 25 K. The quadrupole splitting (ΔEQ) in the range of 1.01-1.03 mm/s confirmed the low-spin state of the iron.