Experimental and theoretical methods to investigate extraframework species in a layered material of dodecaniobate anions.

The highly charged dodecaniobate Keggin ions [XNb12O40](-16) (X = Si, Ge) and [XNb12O40](-15) (X = P) serve as building blocks of self-assembled, low-dimensional anionic framework materials. In addition to its high charge, the Keggin ion provides optimal binding geometries that render these materials as attractive metal sorbents and ion exchangers. We describe here the synthesis and single-crystal X-ray structure of K(10-x)[Nb2O2][HxGeNb12O40].

Out-of-center distortions in d(0) transition metal oxide fluoride anions.

Electronic effects and the bond network are the two factors that cause out-of-center distortions in octahedral d(0) transition metal oxide fluoride anions. Overlap between filled oxide p orbitals and vacant cation d orbitals results in strong, short metal-oxide bonds causing the metal ion to distort toward the oxide ligand. This primary, electronic distortion is not dependent on the extended structure.