Determining the Effects of Zero-Field Splitting and Magnetic Exchange in Dimeric Europium(II) Complexes

• Published in: Inorganic chemistry 2024-05, Vol.63 (19), p.8516-8520
• Main Authors: Carpenter, Stephanie H., Mengell, Joshua, Chen, Ju, Jones, Margaret R., Kirk, Martin L., Tondreau, Aaron M.
• Format: Article
• Language: English
• Subjects: europium magnetism; Hamiltonians; ions; ligands; magnetic properties; quantum mechanics
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c00694

Related BAP [BAP = bis­(acyl)­phosphide] and Acac (Acac = β-diketonate) molecules perform as robust supports for both lanthanide and actinide metals. Here, a molecular bimetallic Eu2+ complex was successfully targeted and isolated by employing sodium bis­(mesitoyl)­phosphide [Na­(mesBAP)] in a salt metathesis with EuI2, producing [Eu­( mes BAP) 2 (et 2 o)] 2 (et2o = metal-coordinated diethyl ether). The corresponding Acac-Eu2+ complex was targeted using mesAcac– (1,3-dimesityl-1,3-propanedione), generating [Eu­( mes Acac) 2 (et 2 o)] 2 . Both complexes were characterized by single-crystal X-ray diffraction, UV–vis, IR, and NMR spectroscopies, and variable-temperature magnetic susceptibility. [Eu­( mes BAP) 2 (et 2 o)] 2 was persistent under anaerobic, anhydrous conditions, whereas the analogous [Eu­( mes Acac) 2 (et 2 o)] 2 showed evidence of decomposition under identical conditions. Variable-temperature magnetic susceptibility and magnetization studies of [Eu­( mes BAP) 2 (et 2 o)] 2 and [Eu­( mes Acac) 2 (et 2 o)] 2 were performed, resulting in similar magnetic exchange coupling values of J ex = −0.018 and −0.023 cm–1 and axial zero-field-splitting D values of −0.38 and −0.51 cm–1, respectively.