Multifunctional Magnetic Materials Obtained by Insertion of a Spin-Crossover Fe-III Complex into Bimetallic Oxalate-Based Ferromagnets

The syntheses, structures and magnetic properties of the compounds of formula [Fe-III(sal(2)-trien)] [(MnCrIII)-Cr-II(ox)(3)]center dot CH2Cl2 (1; H(2)sal(2)-trien = N,N'-disalicylidenetriethylene-tetramine, ox = oxalate), [Fe-III(sal(2)-trien)][(MnCrIII)-Cr-II(ox)(3)]center dot CH3OH (2), [In-III(sal(2)-trien)][(MnCrIII)-Cr-II(ox)(3)]center dot 0.25H(2)O center dot 0.25CH(3)OH center dot 0.25CH(3)CN (3), and [In-III(sal(2)-trien)][(MnCrIII)-Cr-II(ox)(3)]center dot CH3NO2 center dot 0.5 H2O (4) are reported. The structure of I presents a 2D honeycomb anionic layer formed by Mn-II and Cr-III ions linked through oxalate ligands and a cationic layer of [Fe(sal(2)-trien)](+) complexes intercalated between the 2D oxalate network. The structures of 2, 3, and 4 present a 3D achiral anionic network formed by Mn-II and Cr-III ions linked through oxalate ligands with [Fe(sal(2)-trien)](+) or [In(sal(2)-trien)](+) complexes and solvent molecules intercalated within the 3D oxalate network. The magnetic properties and Mossbauer spectroscopy of 1 and 2 indicate that these compounds undergo a long-range ferromagnetic ordering at around 5 K and a spin crossover of the intercalated [Fe(sal(2)-trien)](+) complexes above 130 K, which is complete in the case of 1. The magnetic properties of the compounds 3 and 4 confirm the ferromagnetic ordering of the bimetallic oxalate network.