title: Silica-supported Ti chloride tetrahydrofuranates, precursors of Ziegler-Natta catalysts.
abstract: The structural and electronic properties of silica-supported titanium chloride tetrahydrofuranates samples, obtained by impregnating a polymer-grade dehydroxylated silica with TiCl4(thf)2 and TiCl3(thf)3 complexes, precursors of Ziegler-Natta catalysts, are investigated by means of FT-IR, XAS, XES and diffuse reflectance UV-Vis spectroscopy, coupled with DFT calculations. The properties of the two silica-supported samples are very similar, irrespective of the starting precursor. In both cases, most of the chlorine ligands originally surrounding the Ti sites are substituted by oxygen ligands upon grafting on silica. As a consequence, the electronic properties of silica-supported Ti sites are largely different from those of the corresponding precursors, and in both cases most of the grafted Ti sites have a formal oxidation state of +4. The whole set of experimental data provide evidence that mono-nuclear Ti species are mainly present at the silica surface.
authors.affiliation: Department of Chemistry, NIS Centre of Excellence and INSTM University of Torino, via Quarello 15, I-10135 Torino, Italy.
authors.forename: Kalaivani
authors.initials: K
authors.lastname: Seenivasan
authors.forename: Erik
authors.initials: E
authors.lastname: Gallo
authors.forename: Andrea
authors.initials: A
authors.lastname: Piovano
authors.forename: Jenny G
authors.initials: JG
authors.lastname: Vitillo
authors.forename: Anna
authors.initials: A
authors.lastname: Sommazzi
authors.forename: Silvia
authors.initials: S
authors.lastname: Bordiga
authors.forename: Carlo
authors.initials: C
authors.lastname: Lamberti
authors.forename: Pieter
authors.initials: P
authors.lastname: Glatzel
authors.forename: Elena
authors.initials: E
authors.lastname: Groppo