A heptanuclear Fe(II)–Fe(III)6 system with twelve unpaired electrons

The pentadentate ligand 5LH2 = saldptn = N,N′-bis(1-hydroxy-2-benzyliden)-1,7-diamino-4-azaheptane has been prepared by a Schiff base condensation between 1,7-diamino-4-azaheptane and the corresponding salicyaldehyde. Its complexation with Fe(III) gave the high-spin (S=5/2) complex of [FeIII(5L)Cl]. This precursor was combined with [Fe(CN)6]4− and a blue heptanuclear complex [FeII{(CN)FeIII(5L)}6]Cl2 resulted. This system belongs to the class of high-spin molecules possessing twelve unpaired electrons (S=6) as proven by the magnetic susceptibility measurements and Mössbauer spectra.