Dayane M. Reis

V2O5 nanoparticles obtained from a synthetic bariandite-like vanadium oxide: synthesis, characterization and electrochemical behavior in an ionic liquid.

Highly stable and crystalline V(2)O(5) nanoparticles with an average diameter of 15 nm have been easily prepared by thermal treatment of a bariandite-like vanadium oxide, V(10)O(24) x 9 H(2)O. Their characterization was carried out by powder X-ray diffractometry (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopies, and transmission electron microscopy (TEM). The fibrous and nanostructured film obtained by electrophoretic deposition of the V(2)O(5) nanoparticles showed good electroactivity when submitted to cyclic voltammetry in an ionic liquid-based electrolyte. The use of this film for the preparation of a nanostructured electrode led to an improvement of about 50% in discharge capacity values when compared with similar electrodes obtained by casting of a V(2)O(5) xerogel.

Novel double alkoxides of titanium(IV) and iron(II)/(III): synthetic, structural and spectroscopic studies

The first structurally characterised titanium and iron polynuclear isopropoxides [FeCl{Ti2(OPri)9}], 1, and [Ti3(OMe)2(OPri)9][Fe4TiCl4(O)(OPri)9], 2, have been prepared from 2 : 1 : 1 mixtures of [Ti(OPri)4], K(OPri) and FeCl2. Their identity was confirmed by a number of chemical and physical methods including X-ray diffractometry. Semiempirical quantum mechanical calculations were consistent with an S = 2 ground state for 1. Structural and spectroscopic data support a mixed-valence formulation for the unique {Fe4Ti} anion in 2.

New titanium(IV) and vanadium(IV) haloalkoxides: synthetic route and structural characterisation

The novel binuclear titanium(IV) complex [{TiCl(OPri)2(HOPri )}2(m-OPri)2], 1, and the first mononuclear vanadyl(IV) chloroalcoholate [VCl(O)(HOPri)4]Cl, 2, have been prepared from 2:1:1 mixtures of [Ti(OPri)4], KOPri and VCl3. Products were characterised by elemental analysis, FTIR, EPR, NMR and electronic spectroscopies, magnetic susceptibility measurements and single crystal X-ray diffractometry. A third product was found to be polynuclear and to contain both titanium and vanadium. Semi-empirical quantum-mechanical calculations were carried out for the evaluation of the electronic structure of 1.

Iron(iii) and titanium(iv) oxoalkoxide chemistry: synthetic, structural, magnetochemical and spectroscopic studies of [Ti3(3-OPri)2(-OPri)3(OPri)6][FeCl4] and [Fe5(5-O)(-OPri)8Cl5]Electronic supplementary information (ESI) available: crystallographic data in Tables 5 and 6, and ORTEP-3 representation of the molecular structure of complex C?. See http://www.rsc.org/suppdata/nj/b4/b403899a/

Two synthetic routes were employed for the preparation of iron(III) haloalkoxides in the presence of titanium(IV). Three crystalline products (A, B and C) were isolated and characterised by chemical and physical techniques including X-ray diffractometry, Mossbauer and EPR spectroscopies and variable-temperature magnetic susceptibility measurements. Products B and C are common to both synthetic routes. Product A is a mononuclear iron(II) complex, trans-[FeCl2(HOPri)4], probably produced by the oxidation of propan-2-ol by FeCl3 in the reaction medium. B is the ionic, mixed-metal [Ti3(μ3-OPri)2(μ-OPri)3(OPri)6][FeCl4], while C is a high-yield oxo-haloalkoxide, [Fe5(μ5-O)(μ-OPri)8Cl5]. Magnetic moment measurements in [2H8]-tetrahydrofuran solution from 323 to 173 K indicate that C contains antiferromagnetically coupled iron(III) centres with intermediate (S = 3/2) spin configuration. C is polymorphic in the solid state, crystallising in the monoclinic or the tetragonal systems as non- and mono-solvate species, respectively. The highly (Lewis) acidic character of iron(III), together with its oxophilic character, probably determined the formation of B and C instead of the targeted mixed-metal [FeIIICl(2 − x){Ti2(OPri)(9 + x)}], x = 0 or 1. The possibility of formation of heteronuclear alkoxides containing both iron(III) and titanium(IV) is re-assessed in the light of the results obtained in this work.