Five and Six Coordinated Complexes of Di and Trivalent Iron with Ligands Derived from Acidhydrazides and Acetylacetone

Picolinic acid hydrazide(PH) and isonicotinic acidhydrazide (INH) react with acetylacetone in the presence of iron(II) and iron . (III) salts and give complexes of open chain tetradentate ligands through a template effect. The complexes are isolated and characterised as five and six-coordinated by the help of analyses, conductance, molecular weight, magnetic, Mossbauer, electronic and infrared spectral studies. Two molecules of PH or INH condense with a single acetylacetone moiety giving open chain tetradentate ligands. Attempts to isolate the ligand in the free state are, however, unsuccessful. The Ac(PH)2 coordinates through azomethine and pyridine nitrogens, while Ac(INHh does so through azomethine nitrogens and amide oxygens. Mossbauer spectra are consistent with their proposed geometries and reveal that iron is in the high-spin state. Various ligand field parameters are calculated using normalised spherical harmonic Hamiltonian theory and the amount of distortion is calculated in terms of DT/DQ. Metal- ligand vibrations in the far IR region are discussed