The first 3D and trinuclear cyano-bridged FeIII-FeIII(CN)6 complexes: structure and magnetic characterizations

[Fe(SB)(H2O)]ClO4 and[NEt4](3)[Fe(CN)(6)] react in methanol to give a cis cyano-bridged assembly, 3D[NEt4][Fe(5- CIL1)](2)[Fe(CN)(6)] (5-ClL1H(2) = N, N'-bis(5-chlorosalicylidenato)-2,2-dimethyl-1,3-diaminopropane), 1, and a trans cyano-bridged trinuclear complex, [NEt4][Fe(5-CIL2)(MeOH)](2)[Fe(CN)(6)] (5-CIL2H2 = N, N'-bis (5-chlorosalicylidenato)- 1,2-diaminopropane), 2, depending on the Schiff base used. Complexes 1 and 2 have been characterized by X-ray analyses and magnetic measurements. The four CN-in the equatorial plane of the [Fe(CN)(6)](3)-moiety bridge four Fe ions each in the cis position, which results in a 3D neutral layered structure giving a [-Fe-NC-Fe-CN-Fe-]linkage for 1. The two CN-in the equatorial plane of the [Fe(CN)(6)](3)-moiety bridge two Fe ions, in the trans position, which results in a hydrogen bonded 2D neutral layered structure for 2. Magnetic studies reveal that complex 1 exhibits weak intralayer ferromagnetic coupling, while complex 2 displays transition to a 3D ferromagnetic order between low-spin Fe(III) and high-spin Fe(III) through the cyanide bridges. Complex 2 further displays frequency-dependent alternating current magnetic susceptibility.