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Abstract: The structure and stability of the neutral cages (M12O36 and M18O54, M=Mo and W) of the Keggin and Wells-Dawson anions have been investigated at the level of density functional theory. These neutral cages can be viewed topologically as polyhedra containing triangles (f 3) and squares (f 4). The relative stability of these polyhedra is determined by the location and separation of the f 3, and the α-Keggin cage without fused triangles (N33=0) is, therefore, more stable than the β isomer with N33=3. This rule is also applicable to the Wells-Dawson cages. The structures and stabilities of these neutral cages mimic those of fullerenes within the framework of isolated pentagon rule. [Copyright &y& Elsevier]

Abstract: The structure and stability of the α/β-[AlW12O40]5− anions have been investigated with seven density functional based methods. It has been found that the relative stability of these anions are sensitive to the density functionals, and the α isomer is more stable than the β one in both gas phase and simulated aqueous medium. This conclusion has also been supported by further calculations on the relative stability of the highly charged α/β-[XW12O40] y− (X=Fe(III), Co(III), Zn(II)) anions. The BP86 incorrect assignment of the α/β-[XW12O40]5− (X=Al, Ga) stability in gas phase can be attributed to the insufficient functional. [Copyright &y& Elsevier]