Multimeric oxo-hydroxo Al clusters function as models for common mineral structures and reactions. Cluster research, however, is often slowed by a lack of methods to prepare clusters in pure form and in large amounts. Herein, we report a facile synthesis of the little known cluster Al8(OH)14(H2O)18(SO4)5 (Al8) through a simple dissolution method. We confirm its structure by single-crystal X-ray diffraction and show by 27Al NMR spectroscopy, electrospray-ionization mass spectrometry, and small- and wide-angle X-ray scattering that it also exists in solution. We speculate that Al8 may form in natural water systems through the dissolution of aluminum-containing minerals in acidic sulfate solutions, such as those that could result from acid rain or mine drainage. Additionally, the dissolution method produces a discrete Al cluster on a scale suitable for studies and applications in materials science.
Perkins, C. K.; Eitrheim, E. S.; Fulton, B. L.; Fullmer, L. B.; Colla, C. A.; Park, D.-H.; Oliveri, A. F.; Hutchison, J. E.; Nyman, M.; Casey, W. H.; et al. Synthesis of an Aluminum Hydroxide Octamer through a Simple Dissolution Method. Angew. Chemie Int. Ed. 2017