Thermally-driven processes on rutile TiO2(1 1 0)-(1 × 1): A direct view at the atomic scale

The technological importance of TiO₂ has led to a broad effort aimed at understanding the elementary steps that underlie catalytic and photocatalytic reactions. The most stable surface, rutile TiO₂(1 1 0), in particular, has became a prototypical model for fundamental studies of TiO₂. In this critical review we have selected oxygen, water, and alcohols to evaluate recent progress relevant for applications in the areas of water splitting and oxidation of organic contaminants. We first focus on the characterization of defects and the distribution of excess charge that results from their formation. The subsequent section concentrates on the role of individual surface sites and the effect of available charge in the adsorption processes. The discussion of adsorbate dynamics follows, providing models for intrinsic and extrinsic diffusion processes as well as rotational dynamics of anchored alkoxy species. The final section summarizes our current understanding of TiO₂(1 1 0) catalyzed reactions between water, oxygen, and their dissociation products.     

Silver(I) and mercury(II) complexes with N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane ligands exhibiting three different coordination modes

Treatment of AgNO₃ with one equiv. of N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane (L) afforded a mononuclear complex [Ag(η²-L)NO₃] (1) in which the central silver(I) atom adopts a distorted trigonal planar geometry by coordinating two carbon atoms of the methane moieties of the ligand and one oxygen atom of the NO₃^? group. Interaction of CF₃COOAg with one equiv. of L produced a one-dimensional coordination polymer [Ag₂(μ-L)(CF₃CO₂)₂]_n (2). Each silver(I) in 2 exhibits highly distorted square planar coordination geometry that connects one oxygen atom of L and one neighboring Ag atom with the Ag?Ag interactions. Reaction of HgCl₂ with one equiv. of L resulted in the formation of one-dimensional [{Hg(μ-Cl)Cl}₂(μ-η¹-L)]_n (3) with a C-coordinated dinuclear mercury(II) chloride moiety being linked by L.     

Synthesis,characterization and thermochemistry of Cs(ASP) · nH2O (n = 0, 1)

New compounds of aspartic acid Cs(ASP) · nH₂O (n = 0, 1) have been synthesized and characterized by XRD, IR and Raman spectroscopy as well as TG. The structural formula of this new compound was Cs(ASP) · nH₂O (n = 0, 1). The enthalpy of solution of Cs(ASP) · nH₂O (n = 0, 1) in water were determined. With the incorporation of the standard molar enthalpies of formation of CsOH(aq) and ASP(s), the standard molar enthalpy of formation of −(1202.9 ± 0.2) kJ · mol⁻¹ of Cs(ASP) and −(1490.7 ± 0.2) kJ · mol⁻¹ of Cs(ASP) · H₂O were obtained.     

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

Structural Chemistry - The contents of issues 1 and 2 of Structural Chemistry from the calendar year 2015 are summarized in the present review. A brief thermochemical commentary and possible...     

Structure,crystallization and dielectric resonances in 2–13 GHz of waste-derived glass-ceramic

Structure, kinetics of crystallization, and dielectric resonances of waste-derived glass-ceramic prepared via quench-heating route were studied as a function of dosage of iron ore tailing (IOT) within 20–40 wt% using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vector network analyzer (VNA) measurements. The glass-ceramic mainly consisted of ferrite crystals embedded in borosilicate glass matrix. Crystallization kinetics and morphologies of ferrite crystals as well as coordination transformation of boron between [BO₄] and [BO₃] in glass network were adjustable by changing the amount of IOT. Dielectric resonances in 6–13 GHz were found to be dominated by oscillations of Ca²⁺ cations in glass network with [SiO₄] units on their neighboring sites. Ni²⁺ ions made a small contribution to those resonances. Diopside formed when IOT exceeded 35 wt%, which led to weakening of the resonances.     

Synthesis and structural mechanisms of the 2201-type ferrites and polytypes: Fe2(Sr2 − xAx)FeO6.5 − δ/2 (A = Ba,La, Tl,Pb and Bi)

The Fe₂(Sr_2 ? xA_x)FeO_6.5 ? δ/2 systems have been investigated, by doping the iron rich 2201-type parent structure with Ba²⁺, La³⁺ and 5d¹⁰ post-transition cations. The syntheses have been carried out up to the limit of the 2201-type solid solutions, in order to test the role of the double iron layer Fe₂O_2.5 ? δ/2. The localisation of the charge carriers in these compounds is consistent with their strong antiferro-magnetism. The investigation was then carried out in the transition part of the diagram up to the formation of stable phases. The study of structural mechanisms was carried using high resolution electron microscopy (transmission and scanning transmission), electron diffraction and energy dispersive spectroscopy. Different non-stoichiometry mechanisms are observed, depending on the electronic structure and chemical properties of the doping elements. The specific behavior of the modulated double iron layer is discussed.     

Excess molar volume,viscosity, and refractive index study for the ternary mixture {2-methyl-2-butanol (1) + tetrahydrofuran (2) + propylamine (3)} at different temperatures. Application of the ERAS-model and Peng–Robinson–Stryjek–Vera equation of state

Densities, viscosities, and refractive indices of the ternary mixture consist of {2-methyl-2-butanol (1) + tetrahydrofuran (THF) (2) + propylamine (3)} at a temperature of 298.15 K and related binary mixtures were measured at temperatures of (288.15, 298.15, and 308.15) K at ambient pressure. Data were used to calculate the excess molar volumes and the deviations of the viscosity and refractive index. The Redlich–Kister and the Cibulka equations were used for correlating binary and ternary properties, respectively. The ERAS-model has been applied for describing the binary and ternary excess molar volumes and also Peng–Robinson–Stryjek–Vera (PRSV) equation of state (EOS) has been used to predict the binary and ternary excess molar volumes and viscosities.     

First-principles study on the geometries,stabilities and electronic properties of yttrium–silicon clusters (Y2Si n ; 1 ≤ n ≤ 12)

Structural Chemistry - The geometries, growth patterns, relative stabilities and electronic properties of yttrium-doped silicon clusters Y2Si n (n = 1–12) are systematically...     

Synthesis,characterization and reactions of the transition metal halogenoalkyl carbocation complexes [Cp(CO)2M{η2-CH2CH(CH2)nX}]PF6 (n = 1–8, 10, M = Fe; n = 3, 4 M = Ru; X = Br,I)

The halogenoalkyl complexes [Cp(CO)₂M{(CH₂)_nX}] (n = 3–10, 12, M = Fe; n = 5, 6, M = Ru, X = Br, I) react with Ph₃CPF₆ in dry CH₂Cl₂ to give the corresponding carbocation complexes [Cp(CO)₂M{η²-(CH₂CH(CH₂)_n?2X}]PF₆ in high yields. NMR evidence indicates that the metals form metallacyclopropane type structures with the carbocation ligand. The reactions of some of the cationic complexes with NaI, PPh₃, Na[Cp(CO)₂Fe] and Et₃N are discussed. NaI and Na[Cp(CO)₂Fe] displace the halogeno-olefin, while PPh₃ adds at the β-CH^δ+ giving the unstable phosphonium adducts [Cp(CO)₂Fe{CH₂CH(PPh₃)(CH₂)_n?2X}]PF₆ which decompose to the halogeno-olefins and the cationic PPh₃ complex [Cp(CO)₂Fe(PPh₃)]⁺. Et₃N causes allylic deprotonation forming internal olefin complexes of the type [Cp(CO)₂Fe{CH₂CHCH(CH₂)_n?3X}]PF₆.     

Enhancing the rate capability of high capacity xLi2MnO3 · (1 − x)LiMO2 (M = Mn,Ni, Co) electrodes by Li–Ni–PO4 treatment

The rate capability of high capacity xLi₂MnO₃ · (1 ? x)LiMO₂ (M = Mn, Ni, Co) electrodes for lithium-ion batteries has been significantly enhanced by stabilizing the electrode surface by reaction with a Li–Ni–PO₄ solution, followed by a heat-treatment step. Reversible capacities of 250 mAh/g at a C/11 rate, 225 mAh/g at C/2 and 200 mAh/g at C/1 have been obtained from 0.5Li₂MnO₃ · 0.5LiNi_0.44Co_0.25Mn_0.31O₂ electrodes between 4.6 and 2.0 V. The data bode well for their implementation in batteries that meet the 40-mile range requirement for plug-in hybrid vehicles.     

Modelling (vapour + liquid) and (vapour + liquid + liquid) equilibria of {water (H2O) + methanol (MeOH) + dimethyl ether (DME) + carbon dioxide (CO2)} quaternary system using the Peng–Robinson EoS with Wong–Sandler mixing rule

The (vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) binary data from literature were correlated using the Peng–Robinson (PR) equation of state (EoS) with the Wong–Sandler mixing rule (WS). Two group contribution activity models were used in the PRWS: UNIFAC–PSRK and UNIFAC–Lby. The systems were successfully extrapolated from the binary systems to ternary and quaternary systems. Results indicate that the PRWS–UNIFAC–PSRK generally displays a better performance than the PRWS–UNIFAC–Lby.     

Viscosity of {xCO2 + (1 − x)CH4} with x = 0.5174 for temperatures between (229 and 348) K and pressures between (1 and 32) MPa

A vibrating wire instrument, in which the wire was clamped at both ends, was used to measure the viscosity of {xCO₂ + (1 − x)CH₄} with x = 0.5174 with a combined uncertainty of 0.24 μPa · s (a relative uncertainty of about 0.8 %) at temperatures T between (229 and 348) K and pressures p from (1 to 32) MPa. The corresponding mass density ρ, estimated with the GERG-2008 equation of state, varied from (20 to 600) kg · m⁻³. The measured viscosities were consistent within combined uncertainties with data obtained previously for this system using entirely different experimental techniques. The new data were compared with three corresponding states-type models frequently used for predicting mixture viscosities: the Extended Corresponding States (ECS) model implemented in REFPROP 9.1; the SUPERTRAPP model implemented in MultiFlash 4.4; and a corresponding states model derived from molecular dynamics simulations of Lennard Jones fluids. The measured viscosities deviated systematically from the predictions of both the ECS and SUPERTRAPP models with a maximum relative deviations of 11 % at (229 K, 600 kg · m⁻³) and −16 % at (258 K, 470 kg · m⁻³), respectively. In contrast, the molecular dynamics based corresponding states model, which is predictive for mixtures in that it does not contain any binary interaction parameters, reproduced the density and temperature dependence of the measured viscosities well, with relative deviations of less than 4.2 %.