title: Peroxo-Zr/Hf-containing undecatungstosilicates and -germanates.
abstract: A family of dimeric, peroxo-containing heteropolytungstates, [M(2)(O(2))(2)(XW(11)O(39))(2)](12-) [M = Zr(4+), X = Si (1), Ge (2); M = Hf(4+), X = Si (3)], have been synthesized by reacting ZrCl(4)/HfCl(4) with the respective monolacunary Keggin precursor [XW(11)O(39)](8-) (X = Si, Ge) in an aqueous acidic medium (pH 4.8). The isostructural polyanions 1-3 are composed of two (XW(11)O(39)) Keggin units encapsulating a central diperoxo-dimetal fragment {M(2)(O(2))(2)}(4+) (M = Zr(4+), Hf(4+)). Cyclic voltammetry and exhaustive electrolysis studies indicate fast reductive release of the peroxo ligands upon reduction of 1-3. Stoichiometric oxo-transfer studies from 1-3 to the substrate l-methionine were performed, and the reactions were monitored by (1)H NMR.
authors: School of Engineering and Science, Jacobs University, P.O. Box 750 561, 28725 Bremen, Germany.
authors: Sib Sankar
authors: SS
authors: Mal
authors: Nadeen H
authors: NH
authors: Nsouli
authors: Mauro
authors: M
authors: Carraro
authors: Andrea
authors: A
authors: Sartorel
authors: Gianfranco
authors: G
authors: Scorrano
authors: Holger
authors: H
authors: Oelrich
authors: Lorenz
authors: L
authors: Walder
authors: Marcella
authors: M
authors: Bonchio
authors: Ulrich
authors: U
authors: Kortz