Bis-silsesquioxane complex as a molecular model of transition metal oxide-zeolite nanocomposite

Heterometallic nanocomposite oxide catalysts have been obtained by impregnation of NaY zeolite with toluene solutions of a structurally characterized heterometallic heteroleptic alkoxide, Co2Nb2(acac)(2)(OMe)(12). EXAFS studies showed the molecular structure of the complex to be preserved and the coordination of the late transition metal atom in the ready nanocomposite very close to that in the original complex. A silsesquioxane complex has been used in order to prepare a zeolite nanocomposite analogue and this proved successful with very similar EXAFS spectra to the ready nanocomposite, indicating the usefulness of the sils-esquioxanes as molecular analogues of zeolites. (C) 2004 Elsevier B.V. All rights reserved.