title: Convenient synthesis of fluoride-alkoxides of Nb(V) and Ta(V): a spectroscopic, crystallographic and computational study.
abstract: The synthesis and the spectroscopic characterization of fluoride-alkoxides of niobium and tantalum in the highest oxidation state are reported. Suspensions of MF(5) (M = Nb, Ta) in a chlorinated solvent reacted with up to three equivalents of ROSiMe(3) (R = Me, Et, Ph) to afford polynuclear derivatives and variable amounts of FSiMe(3). Thus MF(4)(OR) (R = Et, Ph) and MF(3)(OR)(2) were obtained by selective 1 : 1 and 1 : 2 reactions almost exclusively as single isomeric products; otherwise mixtures of MF(4)(OMe) species were afforded from the equimolar reactions of MF(5) with MeOSiMe(3). The 1 : 3 reaction of TaF(5) with MeOSiMe(3) led to different forms of TaF(2)(OMe)(3). The synthesis of TaF(OPh)(4) was forced by high temperature conditions or the use of a large excess of PhOSiMe(3). DFT studies were carried out in order to predict, in the distinct cases, the most stable structures of the metal products. The molecular structures of [NbF(2)(OPh)(2)(μ-F)](3) and [TaF(OPh)(3)(μ-OPh)](2) were ascertained by X-ray diffraction.
authors.affiliation: University of Venezia, Dipartimento di Scienze Molecolari e Nanosistemi, Dorsoduro 2137, I-30123 Venezia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bortoluzzi
authors.forename: Nicola
authors.initials: N
authors.lastname: Guazzelli
authors.forename: Fabio
authors.initials: F
authors.lastname: Marchetti
authors.forename: Guido
authors.initials: G
authors.lastname: Pampaloni
authors.forename: Stefano
authors.initials: S
authors.lastname: Zacchini