2D Bimetallic Oxalate‐Based Ferromagnets with Inserted [Fe(4‐Br‐sal2‐trien)]+ and [Fe(3‐R‐sal2‐trien)]+ (R = Br, Cl and CH3O) FeIII Spin‐Crossover Complexes

Abstract

AbstractThe syntheses, structures and magnetic properties of the compounds of formula [FeIII(4‐Br‐sal2‐trien)][MnIICrIII(ox)3]0.67Cl0.33·CH3OH_solvate (1), [FeIII(3‐Br‐sal2‐trien)][MnIICrIII(ox)3]·(CH3CN)2 (2), [FeIII(3‐Cl‐sal2‐trien)][MnIICrIII(ox)3]·(CH3OH)2·(CH3CN)2 (3) and [FeIII(3‐CH3O‐sal2‐trien)][MnIICrIII(ox)3]·(CH3OH)·(H2O)1.5·(CH2Cl2)0.5 (4) are reported. The four structures present a 2D honeycomb anionic layer formed by MnII and CrIII ions linked through oxalate ligands and a cationic layer of the FeIII complexes intercalated between the 2D oxalate network. The main differences compared with previous 2D oxalate‐based structures are the presence of double layers of cations in compounds 1, 3 and 4 and porous channels in the structures of 1 and 4 filled with disordered solvent molecules. The magnetic properties indicate that the inserted FeIII cations undergo an almost complete spin crossover above 300 K in 1 and a partial spin crossover in 3 and 4 that coexists with a ferromagnetic ordering of the oxalate network. In the case of 2, the inserted cation remains in the HS from 2 to 300 K. Therefore, 1, 3 and 4 are multifunctional compounds with coexistence of spin crossover and magnetic ordering. Conversely, photomagnetic characterization shows that 1 and 3 do not present a LIESST effect in contrast to the 2D compound [FeIII(sal2‐trien)][MnIICrIII(ox)3]·(CH2Cl2). These results could help to clarify this rare property for a FeIII complex.