Mononuclear and tetranuclear Fe(III) complexes with two different types of N, O donor Schiff base ligands

A mononuclear Fe(III) complex of a tetradentate N2O2 donor Schiff base ligand derived from 3-ethoxysalicaldehyde and ethylenediamine has been reported. In addition two tetranuclear Fe(III) complexes with discrete Fe4III(μ4-O) cores have been synthesized and characterized using two Schiff base ligands (H2L1–2) derived from two different aromatic acid hydrazides and diacetyl monoxime. The mononuclear Fe(III) and one of the tetranuclear Fe(III) complexes have been structurally characterized by single-crystal X-ray crystallography. The mononuclear complex has a highly distorted octahedral geometry. The tetranuclear Fe(III) complexes are found to be rare examples with discrete neutral alkoxido–oxido clusters with Fe4III(μ4-O) cores.

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► Synthesis of mononuclear (1) and tetranuclear (2–3) Fe(III) complexes are reported.
► N2O2 donor Schiff base ligands are used.
► 1 and 2 are characterized by single crystal X-ray crystallography.
► 1 has a highly distorted octahedral geometry.
► The tetranuclear Fe(III) complexes have rare discrete FeIII(μ4-O) cores.