title: Synthesis, structural characterization, and molecular modeling of dodecaniobate keggin chain materials.
abstract: Four new isostructural one-dimensional dodecaniobate Keggin materials, Na12[Ti2O2][TNb12O40] x xH2O and Na10[Nb2O2][TNb12O40] x xH2O with T = (Si or Ge), have been synthesized hydrothermally using a Lindqvist-ion salt, Na7[Nb6O19H] x 15H2O, as the precursor. Their structure, consisting of chains of Keggin ions [TNb12O40]16- linked by [Ti2O2]4+ or [Nb2O2]6+ bridges, was solved ab initio from powder diffraction data. The location of the charge-balancing sodium atoms and the water molecules was further investigated by molecular simulations. These compounds were also characterized by IR and solid-state 1H, 29Si, and 23Na MAS NMR spectroscopies. The structural relationships between these and related phases based on similar Keggin ion building units are discussed.
authors.affiliation: Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-0750, USA.
authors.forename: François
authors.initials: F
authors.lastname: Bonhomme
authors.forename: James P
authors.initials: JP
authors.lastname: Larentzos
authors.forename: Todd M
authors.initials: TM
authors.lastname: Alam
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Maginn
authors.forename: May
authors.initials: M
authors.lastname: Nyman