Two C3‐Symmetric Dy3III Complexes with Triple Di‐μ‐methoxo‐μ‐phenoxo Bridges, Magnetic Ground State, and Single‐Molecule Magnetic Behavior. Issue 27 (30th May 2014)

• Record Type: Journal Article
• Authors: Hänninen, Mikko M.; Mota, Antonio J.; Aravena, Daniel; Ruiz, Eliseo; Sillanpää, Reijo; Camón, Agustín; Evangelisti, Marco; Colacio, Enrique
• Is Part Of: Chemistry. Volume 20:Issue 27(2014)
• Page Start: 8410
• Page End: 8420
• Publication Date: 2014-05-30
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402392
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Two series of isostructural <italic>C</italic><sub>3</sub>‐symmetric Ln<sub>3</sub> complexes Ln<sub>3</sub><bold>⋅</bold>[BPh<sub>4</sub>] and Ln<sub>3</sub><bold>⋅</bold>0.33[Ln(NO<sub>3</sub>)<sub>6</sub>] (in which Ln<sup>III</sup>=Gd and Dy) have been prepared from an amino‐bis(phenol) ligand. X‐ray studies reveal that Ln<sup>III</sup> ions are connected by one μ<sub>2</sub>‐phenoxo and two μ<sub>3</sub>‐methoxo bridges, thus leading to a hexagonal bipyramidal Ln<sub>3</sub>O<sub>5</sub> bridging core in which Ln<sup>III</sup> ions exhibit a biaugmented trigonal‐prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self‐consistent field (CASSCF) calculations indicate that the magnetic coupling between the Dy<sup>III</sup> ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest DyO distance, the local magnetic moments are oriented almost perpendicular to the Dy<sub>3</sub> plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the Dy<sup>III</sup> ions are separated by approximately 150 and 177 cm<sup>−1</sup>, for Dy<sub>3</sub><bold>⋅</bold>[BPh<sub>4</sub>] and Dy<sub>3</sub><bold>⋅</bold>0.33[Dy(NO<sub>3</sub>)<sub>6</sub>], respectively. As expected for these large energy gaps, Dy<sub>3</sub><bold>⋅</bold>[BPh<sub>4</sub>] and Dy<sub>3</sub><bold>⋅</bold>0.33[Dy(NO<sub>3</sub>)<sub>6</sub>] exhibit, under zero direct‐current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied <italic>H</italic><sub>dc</sub> field of 1000 Oe, Dy<sub>3</sub><bold>⋅</bold>[BPh<sub>4</sub>] exhibits two thermally activated processes with <italic>U</italic><sub>eff</sub> values of 34.7 and 19.5 cm<sup>−1</sup>, whereas Dy<sub>3</sub><bold>⋅</bold>0.33[Dy(NO<sub>3</sub>)<sub>6</sub>] shows only one activated process with <italic>U</italic><sub>eff</sub>=19.5 cm<sup>−1</sup>.</p> </abstract>