Oligonuclear Fe Complexes (Fe, Fe4, Fe6, Fe9) Derived from Tritopic Pyridine Bis-Hydrazone LigandsStructural, Magnetic, and Mössbauer Studies

Tri-topic pyridine bis-hydrazone ligands produce polynuclear complexes with Fe­(II) and Fe­(III) salts with varying nuclearity and metal ion oxidation states. Mononuclear, tetranuclear, hexanuclear, and nonanuclear examples are discussed using structural, magnetic and Mössbauer data. In one case, although X-ray data suggest a [3 × 3] Fe9 grid (space group P42/n), careful examination of the structure, in conjunction with magnetic and Mössbauer data, indicates an unusual situation where the corner and center sites are present at unit occupancy, whereas side site occupancy is ∼0.6.