Hydrogen bond mediated intermolecular magnetic coupling in mononuclear high spin iron(iii) Schiff base complexes: synthesis, structure and magnetic study with theoretical insight.

The crystal structure and magnetic properties of two mononuclear iron(iii) Schiff base complexes, [FeL 1 (NCS) 2 ] (1), HL 1 = 2-[1-[[2-[(2-aminoethyl)amino]ethyl]imino]ethyl]phenol and [FeL 2 (N 3 )Cl] (2), HL 2 = 2-(-1-(2-(2-aminoethylamino)ethylimino)ethyl)-4-methylphenol are reported. Each complex contains a Fe(iii) ion surrounded by a N 3 O Schiff base ligand and two NCS - ligands (in 1) or one N 3 - and one Cl - ligands (in 2). The magnetic properties can be well reproduced with zero field splittings in the high spin S = 5/2 Fe(iii) ions and weak intermolecular Fe-Fe interactions mediated by hydrogen bonds. This intermolecular antiferromagnetic interaction has been validated by using DFT calculations in complex 2. Moreover, the interaction energies of the H-bonded dimers in both complexes have been estimated using DFT calculations and characterized using a combination of QTAIM and NCI plot computational tools. Complexes 1 and 2 constitute two rare examples of Fe(iii) complexes with magnetic interactions through H-bonds.