Spin crossover mediated by hydrogen bonds in iodine-substituted manganese complexes

Abstract

The reaction of Mn(Ⅱ) salts prepared with (5-I-sal-N-1,5,8,12)2− ligand where the hexadentate ligand is the product of the reaction of 5-iodosalicylaldehyde and N,N’-bis(3-aminopropyl)ethylenediamine in situ in MeOH/EtOH provided five complexes, [Mn(5-I-sal-N-1,5,8,12)]Y (Y = PF6− (1), AsF6− (2), SbF6− (3), BF4− (4), ClO4− (5)). All complexes crystallize without crystallizing solvents, except 4 with a H2O solvent molecule. Different structural features and magnetic profiles have been observed in complexes 1 − 3. Owing to the cooperativity of the NH···F and NH···I hydrogen bonds and I···π, I···F interactions, complexes 1 and 3 persist in the HS state at 2 − 400 K while complex 2 shows a gradual SCO with T1/2 is about 265 K. Hirshfeld face analysis reveals that the presence of different interactions in complexes 1 − 3. With decreasing the temperature, complex 4 undergoes an almost full SCO with T1/2 = 272 K, while complex 5 shows an incomplete SCO and remains 50% HS state until 30 K.