Mononuclear and dinuclear iron(III) compounds with β-diketonate ligands: Synthesis, magnetic behavior and DFT calculations

The synthesis, crystal structure, magnetic properties and DFT calculations of two low-nuclearity Fe(III) compounds based on β-diketonate ligand, [Fe(OMe)(BTA)2]2 (1) and Fe(BTA)3 (2) (BTA = 4,4,4-trifluoro-1-phenyl-2,4-butanedione) are reported. Compound (1) is a molecular dimer in which Fe(III) ions are coordinated to two BTA ligands and bridged by two methoxide anions, while compound (2) is a trischelated Fe(III) monomer. Magnetic measurements revealed antiferromagnetic interactions in both compounds. In (1) the magnetic coupling is intramolecular, whereas in (2) it occurs via intermolecular interactions as a result of π–π stacking between the phenyl rings. DFT calculations using the broken symmetry approach were carried out to obtain the theoretical coupling constant value for both compounds and to rationalize the pathway for magnetic interactions in (2).

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► Compounds with different nuclearities were obtained depending on the order of the reagent addition.
► Intermolecular π–π stacking plays a key role to the magnetic behavior of the mononuclear compound.
► DFT calculations rationalize the pathway for the magnetic interactions.