Solvent-tuned magnetic exchange interactions in Dy2 systems ligated by a μ-phenolato heptadentate Schiff base. Issue 68 (2nd December 2019) - Jiang, Zhijie
Abstract : Solvent-tuning changes the magnetic exchange interaction and results in different magnetic relaxation dynamics in Dy2 systems ligated by a μ-phenolato heptadentate Schiff base. Abstract : A series of binuclear dysprosium compounds, namely, [Dy(api)]2 (1 ), [Dy(api)]2 ·2CH2 Cl2 (2 ), [Dy(Clapi)]2 ·2C4 H8 O (3 ), and [Dy(Clapi)]2 ·2C3 H6 O (4 ) (H3 api = 2-(2-hydroxyphenyl)-1, 3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1, 3-imidazoline; H3 Clapi = 2-(2′-hydroxy-5′-chlorophenyl)-1, 3-bis[3′-aza-4′-(2′′-hydroxy-5′′-chlorophenyl)prop-4′-en-1′-yl]-1, 3-imidazolidine), have been isolated by the reactions of salen-type ligands H3 api/H3 Clapi with DyCl3 ·6H2 O in different solvent systems. Structural analysis reveals that each salen-type ligand provides a heptadentate coordination pocket (N4 O3 ) to encapsulate a Dy III ion and all of the Dy III centers in 1–4 adopt a distorted square antiprism geometry with D 4d symmetry. Magnetic studies showed that compound 1 did not exhibit single-molecule magnetic (SMMs) behavior. With the introduction of different lattice solvents, compounds 2–4 showed filed-induced slow magnetic relaxation with barriers U eff of 18.2 K (2 ), 28.0 K (3 ) and 16.4 K (4 ), respectively. Ab initio calculations were employed to interpret the magnetization behavior of 1–4 . The combination of experimental and theoretical data reveal the importance of the weak exchange interaction between the Dy III ions in the observation of slow magnetic relaxation, and a relaxation mechanism has been developed to rationalize the observed difference in the U eff values. The different lattice solvents influence Dy–O–Dy bond angles and thus alter the torsion of the square antiprism geometry, consequently resulting in distinct magnetic interactions and the magnetic behavior.