Clusters in bis-tridentate tethered domains of an iron chelating drug†

Abstract

The tridentate metal binding domains of iron chelating agents have been tethered via a variable length methylene (CH₂)_n linker (n = 1, 2, 4, 6, 8, 10, 14). The single-crystal X-ray structures of monomeric ([Fe(HL⁸)]·2.5H₂O n = 8; H₄L⁸ is 1,10-decanedioyl di(salicylaldehyde hydrazone)) and dimeric ([{Fe(H₂PL⁴)}₂]Cl₂·2H₂O n = 4; H₄PL⁴ is 1,6-hexanedioyl di(pyridoxal hydrazone)) iron(III) complexes have been determined. The complexes exhibit oligomerism: with chain lengths of n ≥ 6 monomers are prevalent whereas for shorter chains this is not possible and a series of clusters exist as shown by ESMS and molecular modelling.