Iron(III) Complexes with a Biologically Relevant Aroylhydrazone: Crystallographic Evidence for Coordination Versatility

Complexation of iron(III) with the heterodonor chelating agent 3,5-di-tert-butylsalicylidene benzoylhydrazine, H2(3,5-tBu2)salbh, in the
absence or presence of a base affords the complex cation
[Fe{H(3,5-tBu2)salbh}2]+ or the neutral compound [Fe{H(3,5-tBu2)salbh}{(3,5-tBu2)salbh}], respectively, as revealed by single-crystal
X-ray analyses. Such a synthetic and crystallographic demonstration
of the coordination versatility of an aroylhydrazone toward iron is
uncommon. The oxidation and spin states of the iron have been
verified with magnetic and spectroscopic measurements.