Synthesis and Characterization of Cerium-Oxo Clusters Capped by Acetylacetonate

High Resolution Image Download MS PowerPoint Slide Cerium-oxo clusters have applications in fields ranging from catalysis to electronics and also hold the potential to inform on aspects of actinide chemistry. Toward this end, a cerium-acetylacetonate (acac 1– ) monomeric molecule, Ce(acac) 4 ( Ce-1 ), and two acac 1– -decorated cerium-oxo clusters, [Ce 10 O 8 (acac) 14 (CH 3 O) 6 (CH 3 OH) 2 ]·10.5MeOH ( Ce-10 ) and [Ce 12 O 12 (OH) 4 (acac) 16 (CH 3 COO) 2 ]·6(CH 3 CN) ( Ce-12 ), were prepared and structurally characterized. The Ce(acac) 4 monomer contains Ce IV . Crystallographic data and bond valence summation values for the Ce-10 and Ce-12 clusters are consistent with both clusters having a mixture of Ce III and Ce IV cations. Ce L 3 -edge X-ray absorption spectroscopy, performed on Ce-10, showed contributions from both Ce III and Ce IV . The Ce-10 cluster is built from a hexameric cluster, with six Ce IV sites, that is capped by two dimeric Ce III units. By comparison, Ce-12, which formed upon dissolution of Ce-10 in acetonitrile, consists of a central decamer built from edge sharing Ce IV hexameric units, and two monomeric Ce III sites that are bound on the outer corners of the inner Ce 10 core. Electrospray ionization mass spectrometry data for solutions prepared by dissolving Ce-10 in acetonitrile showed that the major ions could be attributed to Ce 10 clusters that differed primarily in the number of acac 1–, OH 1–, MeO 1–, and O 2– ligands. Small angle X-ray scattering measurements for Ce-10 dissolved in acetonitrile showed structural units slightly larger than either Ce 10 or Ce 12 in solution, likely due to aggregation. Taken together, these results suggest that the acetylacetonate supported clusters can support diverse solution-phase speciation in organic solutions that could lead to stabilization of higher order cerium containing clusters, such as cluster sizes that are greater than the Ce 10 and Ce 12 reported herein.