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

The tridentate metal binding domains of iron chelating agents have been tet hered 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)]. 2.5H(2)O n=8; H4L8 is 1,10-decanedioyl di(salicylaldehyde hydrazone)) and dimeric ( [{Fe(H2PL4)}(2)]Cl-2. 2H(2)O n=4; H4PL4 is 1,6-hexanedioyl di(pyridoxal hyd razone)) iron(III) complexes have been determined. The complexes exhibit ol igomerism: with chain lengths of n greater than or equal to 6 monomers are prevalent whereas for shorter chains this is not possible and a series of c lusters exist as shown by ESMS and molecular modelling.