Isolation and characterization of the [Ga2Al18O8(OH)36(H2O)12]8+ cluster: cationic variations on the Wells–Dawson topology

Abstract

The structural chemistry of Group 13 polyoxometalates lags far behind related negatively charged transition metal species and limits the development of advanced materials. A novel heterometallic cluster [Ga₂Al₁₈O₈(OH)₃₆(H₂O)₁₂]⁸⁺ (Ga₂Al₁₈) has been isolated using a supramolecular approach and structurally characterized using single-crystal X-ray diffraction. Ga₂Al₁₈ represents the Wells–Dawson structure polycations and variations in the structural topology may be related to the initial stabilization of the Keggin isomer. DFT calculations on the related ε-Keggins (GaAl₁₂ and Al₁₃), Ga₂Al₁₈, and theoretical Al₂Al₁₈ clusters reveal similar features of electronic structure, suggesting additional heteroatom substitution in other isostructural clusters should be possible.