Transmetalation of Aqueous Inorganic Clusters: A Useful Route to the Synthesis of Heterometallic Aluminum and Indium HydroxoAquo Clusters

[Al_<i>x</i>In_<i>y</i>(μ₃-OH)₆(μ-OH)₁₈(H₂O)₂₄]­(NO₃)₁₅ hydroxy–aquo clusters (<b>Al_<i>x</i>In_{13–<i>x</i>}</b>) are synthesized through the evaporation of stoichiometrically varied solutions of <b>Al₁₃</b> and In­(NO₃)₃ using a transmetalation reaction. Several spectroscopic techniques (¹H NMR, ¹H-diffusion ordered spectroscopy, dynamic light scattering, and Raman) are used to compare <b>Al_<i>x</i>In_{13–<i>x</i>}</b> to its <b>Al₁₃</b> counterpart. A thin film of aluminum indium oxide was prepared from an <b>Al₇In₆</b> cluster ink, showing its utility as a precursor for materials

Minerals to Materials: Bulk Synthesis of Aqueous Aluminum Clusters and Their Use as Precursors for Metal Oxide Thin Films

We describe a process to produce aqueous precursor solutions of the <i><b>flat</b></i><b>-Al</b>_<b>13</b> hydroxo cluster (Al₁₃(μ₃-OH)₆(μ₂-OH)₁₈(H₂O)₂₄(NO₃)₁₅) via stoichiometric dissolution of bulk Al­(OH)₃(s) in HNO₃(aq). We highlight its facility by demonstrating high yields and large-scale synthesis. X-ray diffraction confirms formation of a single-phase product, and Raman spectra show characteristic O-Al-O vibrational modes, both techniques confirming the identity of the <i><b>flat</b></i><b>-Al</b>_<b>13</b> cluster in the bulk. ²⁷Al NMR spectroscopy and dynamic light scattering also confirm the presence of the cluster in aqueous solution. We show the as-prepared solution produces smooth and continuous thin films via spin-coating. In capacitors, the films exhibit low leakage currents (near 10 nA/cm²) and dielectric constants expected for amorphous Al₂O₃. Because the precursor preparation requires no postsynthesis purification, it is readily scalable to large volumes