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.