Synthesis and spectral properties of titanium(iv) polynuclear hydroxo complexes stabilized in solution by the [PW11O39]7− heteropolyanion

Detsuheva, L. G.; Fedotov, M. A.; Кузнецова, Л. И.; Власов, А. А.; Likholobov, V. A.

doi:10.1007/bf02496109

Cited by 6 publications

(3 citation statements)

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“…(The EELS spectrum was a composite average of six separate experiments that was subsequently numerically smoothed to remove noise.) The spectral width of the EELS feature associated with O 2 on TiO 2 (110) is similar to that reported for O 2 –Ti 4+ complexes in the literature. ,,− In the case of the EELS measurement, the width of the 2.8 eV loss (at the equivalent of 443 nm) is not due to an instrumental resolution limitation. The full width at half-maximum of the elastic peak was ∼60 meV, which, at 2.8 eV, would correspond to a spectral resolution of ∼5 nm (as illustrated in the inset of Figure ).…”

Section: Resultssupporting

confidence: 84%

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

et al. 2013

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We have examined the chemical and photochemical properties of molecular oxygen on the (110) surface of rutile TiO 2 at 100 K using electron energy loss spectroscopy (EELS), photon stimulated desorption (PSD), and scanning tunneling microscopy (STM). Oxygen chemisorbs on the TiO 2 (110) surface at 100 K through charge transfer from surface Ti 3+ sites. The charge-transfer process is evident in EELS by a decrease in the intensity of the Ti 3+ d-to-d transition at ∼0.9 eV and formation of a new loss at ∼2.8 eV. On the basis of comparisons with the available homogeneous and heterogeneous literature for complexed/adsorbed O 2 , the species responsible for the 2.8 eV peak can be assigned to a surface peroxo (O 2 2− ) state of O 2 . This species was identified as the active form of adsorbed O 2 on TiO 2 (110) for PSD. The adsorption site of this peroxo species was assigned to that of a regular five-coordinated Ti 4+ (Ti 5c ) site based on comparisons between the UV exposure-dependent behavior of O 2 in STM, PSD, and EELS data. Assignment of the active form of adsorbed O 2 to a peroxo species at normal Ti 5c sites necessitates reevaluation of the simple mechanism in which a single valence band hole neutralizes a singly charged O 2 species (superoxo or O 2 − ), leading to desorption of O 2 from a physisorbed potential energy surface.

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Section: Resultssupporting

confidence: 84%

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

et al. 2013

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“…The spectrum shows WO peaks at 700–740 ppm, W–O–W peaks at 400–450 ppm, and a single isolated peak at 570 ppm, which is assigned to the terminal oxygen atoms in the vacant site of {PW 11 } based on a comparison to the literature values for diamagnetic transition-metal-substituted derivatives of this POM . To our knowledge, this is the first report of the 17 O NMR spectrum of {PW 11 } or any POM with oxygens containing such high local electron densities.…”

Section: Resultsmentioning

confidence: 73%

Revisiting the Polyoxometalate-Based Late-Transition-Metal-Oxo Complexes: The “Oxo Wall” Stands

et al. 2012

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Terminal oxo complexes of the late transition metals Pt, Pd, and Au have been reported by us in Science and Journal of the American Chemical Society. Despite thoroughness in characterizing these complexes (multiple independent structural methods and up to 17 analytical methods in one case), we have continued to study these structures. Initial work on these systems was motivated by structural data from X-ray crystallography and neutron diffraction and (17)O and (31)P NMR signatures which all indicated differences from all previously published compounds. With significant new data, we now revisit these studies. New X-ray crystal structures of previously reported complexes K(14)[P(2)W(19)O(69)(OH(2))] and "K(10)Na(3)[Pd(IV)(O)(OH)WO(OH(2))(PW(9)O(34))(2)]" and a closer examination of these structures are provided. Also presented are the (17)O NMR spectrum of an (17)O-enriched sample of [PW(11)O(39)](7-) and a careful combined (31)P NMR-titration study of the previously reported "K(7)H(2)[Au(O)(OH(2))P(2)W(20)O(70)(OH(2))(2)]." These and considerable other data collectively indicate that previously assigned terminal Pt-oxo and Au-oxo complexes are in fact cocrystals of the all-tungsten structural analogues with noble metal cations, while the Pd-oxo complex is a disordered Pd(II)-substituted polyoxometalate. The neutron diffraction data have been re-analyzed, and new refinements are fully consistent with the all-tungsten formulations of the Pt-oxo and Au-oxo polyoxometalate species.

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“…Once all the blue color associated with 1 red had been discharged, an 0.5 mL aliquot of the now colorless solution was transferred to a UV−vis cell that contained 2 mL of a 5 mM solution of H 5 TiPW 11 O 40 in 0.8 M H 2 SO 4 . Under these conditions, 5 min are sufficient for the reaction with H 2 O 2 to give the yellow (TiO 2 )PW 11 O 39 5- peroxo-complex , (λ max = 392 nm) in quantitative yield. In a separate control experiment, identical conditions were used to determine the extinction coefficient of authentic (TiO 2 )PW 11 O 39 5- : ε 392 = (1.7 ± 0.1) × 10 3 M -1 cm -1 , which is in good agreement with the published value of 1.6 × 10 3 M -1 cm -1 .…”

Section: Methodsmentioning

confidence: 99%

Reduction of O₂ to Superoxide Anion (O₂^•^-) in Water by Heteropolytungstate Cluster-Anions

et al. 2006

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Fundamental information concerning the mechanism of electron transfer from reduced heteropolytungstates (POM(red)) to O2, and the effect of donor-ion charge on reduction of O2 to superoxide anion (O2.-), is obtained using an isostructural series of 1e--reduced donors: alpha-X(n+)W12O40(9-n)-, X(n+) = Al3+, Si4+, P5+. For all three, a single rate expression is observed: -d[POM(red)]/dt = 2k12[POM(red)][O2], where k12 is for the rate-limiting electron transfer from POM(red) to O2. At pH 2 (175 mM ionic strength), k12 increases from 1.4 +/- 0.2 to 8.5 +/- 1 to 24 +/- 2 M-1s-1 as Xn+ is varied from P5+ (3red) to Si4+ (2red) to Al3+ (1red). Variable-pH data (for 1red) and solvent-kinetic isotope (KIE = kH/kD) data (all three ions) indicate that protonated superoxide (HO2.) is formed in two steps--electron transfer, followed by proton transfer (ET-PT mechanism--rather than via simultaneous proton-coupled electron transfer (PCET). Support for an outersphere mechanism is provided by agreement between experimental k12 values and those calculated using the Marcus cross relation. Further evidence is provided by the small variation in k12 observed when Xn+ is changed from P5+ to Si4+ to Al3+, and the driving force for formation of O2.- (aq), which increases as cluster-anion charge becomes more negative, increases by nearly +0.4 V (a decrease of >9 kcal mol-1 in DeltaG degrees ). The weak dependence of k12 on POM reduction potentials reflects the outersphere ET-PT mechanism: as the anions become more negatively charged, the "successor-complex" ion pairs are subject to larger anion-anion repulsions, in the order [(3(ox)3-)(O2.-)]4- < [(2(ox)4-)(O2.-)]5- < [(1(ox)5-)(O2.-)]6-. This reveals an inherent limitation to the use of heteropolytungstate charge and reduction potential to control rates of electron transfer to O2 under turnover conditions in catalysis.

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Synthesis and spectral properties of titanium(iv) polynuclear hydroxo complexes stabilized in solution by the [PW11O39]7− heteropolyanion

Abstract: To date, heteropolycomplexes in which one or several Tire ions are involved in the HPA framework (for example, [PWtiTi04015-, 7 [PWloTi204017-, s and [Ge2Ti6W18077]14-) have been prepared and structurally characterized. 9 In this work, we synthesized polynuclear

Cited by 6 publications

References 9 publications

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

Revisiting the Polyoxometalate-Based Late-Transition-Metal-Oxo Complexes: The “Oxo Wall” Stands

Reduction of O₂ to Superoxide Anion (O₂^•^-) in Water by Heteropolytungstate Cluster-Anions

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Synthesis and spectral properties of titanium(iv) polynuclear hydroxo complexes stabilized in solution by the [PW11O39]7− heteropolyanion

Abstract: To date, heteropolycomplexes in which one or several Tire ions are involved in the HPA framework (for example, [PWtiTi04015-, 7 [PWloTi204017-, s and [Ge2Ti6W18077]14-) have been prepared and structurally characterized. 9 In this work, we synthesized polynuclear

Cited by 6 publications

References 9 publications

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O2 from the Rutile TiO2(110) Surface

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O2 from the Rutile TiO2(110) Surface

Revisiting the Polyoxometalate-Based Late-Transition-Metal-Oxo Complexes: The “Oxo Wall” Stands

Reduction of O2 to Superoxide Anion (O2•-) in Water by Heteropolytungstate Cluster-Anions

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Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O₂ from the Rutile TiO₂(110) Surface

Reduction of O₂ to Superoxide Anion (O₂^•^-) in Water by Heteropolytungstate Cluster-Anions