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Lanthanide Differentiation using Acetylacetonate: Insights into the Solution Speciation and Crystallization Behavior of Homo‐ and Heterometal Complexes
Journal article   Open access   Peer reviewed

Lanthanide Differentiation using Acetylacetonate: Insights into the Solution Speciation and Crystallization Behavior of Homo‐ and Heterometal Complexes

Morgan A. McDonald, Frenio A. Redeker, Paschal Akubuiro, Pere Miró, Jeffery A. Bertke, Kaveh Jorabchi and Karah E. Knope
European journal of inorganic chemistry, Vol.28(16), e202500171
06/05/2025
DOI: 10.1002/ejic.202500171
url
https://doi.org/10.1002/ejic.202500171View
Published (Version of record) Open Access

Abstract

The lanthanides form a chemically cohesive series, and identifying differences that can be leveraged to separate near neighbors remains an ongoing need. Here, the synthesis, structural chemistry, and spectroscopic properties of a neodymium‐acetylacetonate monomer, [Nd(acac)3(H2O)2] (Nd‐1), and an acac‐bridged Nd‐dimer, [Nd2(acac)6(H2O)2] (Nd‐2), are described. Interestingly, the Nd dimer readily precipitated from solution; however, efforts to the crystallize the Dy analog using the same synthetic approach were unsuccessful. Yet heterometal dimers, [Nd2‐xDyx(acac)6(H2O)2] (NdDy‐2), could be prepared from mixed metal solutions. To understand these differences in crystallization behavior of Nd‐ and Dy‐acac complexes, the solution speciation of Ln‐acac systems was examined using nano‐electrospray ionization mass spectrometry (nESI‐MS). Both homometal and heterometal solutions were prepared (Ln = Nd, Dy, Nd/Dy). nESI‐MS showed the presence of homometallic dimeric species for Nd and Dy and peaks consistent with both homo‐ and heterometallic complexes in mixed metal solutions. Density functional theory was used to further understand intrinsic differences in nucleation energetics in dimeric homo‐ and heterometallic species. Overall, this work provides fundamental insight into the correlation between solution‐ and solid‐state structural units and differences in the crystallization behavior of Ln complexes; the latter is particularly relevant to separating metal ions with otherwise very similar chemical behavior.
ESI-MS heterometallics lanthanides oligomers speciations

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