The reaction of stoichiometric amount of FeCl3, Schiff-base ligand, NaBPh4 in CH3CN and 3,5-DTBC in CH3OH under O2 did produce a new μ-oxo-bridged hexanuclear iron(III) cluster [Fe6(L)2(μ3-O)2(μ-3,5-DTBC)4(μ-CH3O)2(Cl)2] (BPh4)2 · 2H2O (1) (L = N,N-diethylenetriamino-bis(imidazolaldiminato) with a spin ground state of S = 5.