A new family of Fe4Ln4 (Ln = DyIII, GdIII, YIII) wheel type complexes with ferromagnetic interaction, magnetocaloric effect and zero-field SMM behavior. Issue 21 (7th September 2021)

• Record Type: Journal Article
• Authors: Mondal, Arpan; Raizada, Mukul; Sahu, Pradip Kumar; Konar, Sanjit
• Is Part Of: Inorganic chemistry frontiers. Volume 8:Issue 21(2021)
• Page Start: 4625
• Page End: 4633
• Publication Date: 2021-09-07
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1qi00781e
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Observation of ferromagnetic interactions and single molecule toroic (SMT) behavior in Fe4 Ln4 wheel complexes. Abstract : In this work, we report three isostructural Fe4 Ln4 wheel type complexes with molecular formula [{Fe4 (dea)4 Dy4 (deaH)8 (μ2 -OMe)4 }(NO3 )4 ]·4(H2 O) (1 ), [{Fe4 (dea)4 Gd4 (deaH)8 (μ2 -OMe)4 }·(NO3 )4 ]·4(H2 O)·4(MeOH) (2 ) and [{Fe4 (dea)4 Y4 (deaH)8 (μ2 -OMe)4 }(NO3 )4 ]·4(H2 O)·6(MeOH) (3 ), (where dea = diethanolamine). Detailed structural analysis discloses that the 4Ln III and 4Fe III ions are connected alternatively in a cyclic arrangement through the oxo-bridging of methanol and diethanolamine molecules. The detailed magnetic measurements reveal the presence of ferromagnetic exchange interactions between the Ln III and Fe III centers in complexes 1 and 2, whereas a weak antiferromagnetic interaction is observed between Fe III centers in complex 3 . In addition, complex 1 shows slow magnetic relaxation behavior ( U eff = 9.8 K) under zero field and a remarkable entropy change was observed for complex 2 at 7 T magnetic field (magnetocaloric effect = 31.15 J kg −1 K −1 ). The ab initio calculations disclose the presence of strong axial anisotropy and a minimum transverse component ( g x = 0.0024, g y = 0.0062, and g z = 19.82) in the ground state of each Dy III ion for complex 1 . It was also found that the local anisotropy axis on each Dy III ion is arranged in a vortex-like structure as observed in single molecule toroics (SMTs). From BS-DFT calculations, it was found that the exchange interactions between Fe–Ln metal centers mainly follow the charge transfer process between 3d and 4f orbitals.