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Updated: Jun 27, 2025
Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
Determining the Effects of Zero-Field Splitting and Magnetic Exchange in Dimeric Europium(II) Complexes
Stephanie H Carpenter1, Joshua Mengell2, Ju Chen2
1Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
Abstract:
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(BAP)(eto)] (et2o = metal-coordinated diethyl ether). The corresponding Acac-Eu2+ complex was targeted using mesAcac- (1,3-dimesityl-1,3-propanedione), generating [Eu(Acac)(eto)]. Both complexes were characterized by single-crystal X-ray diffraction, UV-vis, IR, and NMR spectroscopies, and variable-temperature magnetic susceptibility. [Eu(BAP)(eto)] was persistent under anaerobic, anhydrous conditions, whereas the analogous [Eu(Acac)(eto)] showed evidence of decomposition under identical conditions. Variable-temperature magnetic susceptibility and magnetization studies of [Eu(BAP)(eto)] and [Eu(Acac)(eto)] were performed, resulting in similar magnetic exchange coupling values of Jex = -0.018 and -0.023 cm-1 and axial zero-field-splitting D values of -0.38 and -0.51 cm-1, respectively.
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