Composition of vapor and thermodynamic characteristics of gaseous molecules of alkali metals tungstates

2020 ◽  
Vol 4 ◽  
pp. 80-84
Author(s):  
E.K. Kazenas ◽  
◽  
Yu.V. Tsvetkov ◽  
G.K. Astakhova ◽  
V.A. Volchenkova ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Thermodynamic Characteristic ◽  
Mass Spectra ◽  
Alkali Metals ◽  
Thermodynamic Characteristics ◽  
Vapor Pressures ◽  
Metal Tungstates

Calculated and experimental mass spectra (at temperatures region of 1100-1500 K) of alkali metals tungstates are presented. Vapor pressures and thermodynamic characteristic of gaseous alkali metal tungstates are determined.

Vapor Composition and Thermodynamic Characteristics of Gaseous Molecules of Alkali Metal Tungstates

2021 ◽  
Vol 12 (3) ◽  
pp. 842-845
Author(s):  
E. K. Kazenas ◽  
Yu. V. Tsvetkov ◽  
G. K. Astakhova ◽  
V. A. Volchenkova ◽  
N. A. Andreeva ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Thermodynamic Characteristics ◽  
Vapor Composition ◽  
Metal Tungstates

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

scholarly journals Spotlight on Alkali Metals: The Structural Chemistry of Alkali Metal Thallides

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1013
Author(s):  
Stefanie Gärtner
Keyword(s):  
Crystal Structure ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Valence Electron ◽  
Oxidation States ◽  
Valence Electron Concentration ◽  
Base Metals ◽  
Charge Balancing

Alkali metal thallides go back to the investigative works of Eduard Zintl about base metals in negative oxidation states. In 1932, he described the crystal structure of NaTl as the first representative for this class of compounds. Since then, a bunch of versatile crystal structures has been reported for thallium as electronegative element in intermetallic solid state compounds. For combinations of thallium with alkali metals as electropositive counterparts, a broad range of different unique structure types has been observed. Interestingly, various thallium substructures at the same or very similar valence electron concentration (VEC) are obtained. This in return emphasizes that the role of the alkali metals on structure formation goes far beyond ancillary filling atoms, which are present only due to charge balancing reasons. In this review, the alkali metals are in focus and the local surroundings of the latter are discussed in terms of their crystallographic sites in the corresponding crystal structures.

CO2 Adsorption on the B12N12 Nanocage Encapsulated with Alkali Metals: A Density Functional Study

NANO ◽  
2019 ◽  
Vol 14 (03) ◽  
pp. 1950034
Author(s):  
Ximin Liang ◽  
Qiyan Zhang ◽  
Qinfu Zhao ◽  
He Zhao ◽  
Yifan Feng ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Density Functional ◽  
Alkali Metals ◽  
Large Change ◽  
Functional Study ◽  
Functional Theory ◽  
Metal Atoms ◽  
Adsorption Of Co ◽  
Physical And Chemical ◽  
Homo Lumo

Density functional theory (DFT) calculations have been carried out to study the capacity of the B[Formula: see text]N[Formula: see text] nanocage encapsulated with alkali metals (Li, Na, K) for the CO2 adsorption and activation. It is found that after encapsulating alkali metals, the alkali metal atoms are closer to one side of clusters instead of exactly lying at the center, and a considerable charge transfers from the inner alkali metal atoms to the B[Formula: see text]N[Formula: see text] cage. Besides, the HOMO–LUMO gap (HLG) values of Li@B[Formula: see text]N[Formula: see text], Na@B[Formula: see text]N[Formula: see text] and K@B[Formula: see text]N[Formula: see text] are decreased to about 6[Formula: see text]eV, being much smaller than that of the pristine B[Formula: see text]N[Formula: see text]. Although the geometry structure parameters and the energy differences of M06-2X are slightly different from the ones of [Formula: see text]B97X-D, some identical results of two kinds of functional can be obtained. CO2 can be adsorbed chemically and physically on majority bonds of all the clusters, except for some bonds with large change in bond length and bond indices. The encapsulation of alkali-metal atoms may enhance the physical and chemical adsorption of CO2 on the surface of the clusters, in which Na@B[Formula: see text]N[Formula: see text] and K@B[Formula: see text]N[Formula: see text] are the most powerful physical and chemical adsorbent for CO2, respectively.

Mass Spectrometric Behaviour of Carboxylated Polyethylene Glycols and Carboxylated Octylphenol Ethoxylates

2003 ◽  
Vol 9 (3) ◽  
pp. 165-173 ◽  
Author(s):  
Magdalena Frańska ◽  
Agnieszka Zgoła ◽  
Joanna Rychłowska ◽  
Andrzej Szymański ◽  
Zenon Łukaszewski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Alkali Metal ◽  
Mass Spectra ◽  
Secondary Ion Mass Spectrometry ◽  
Metal Cations ◽  
Mass Spectrometric ◽  
Polyethylene Glycols ◽  
Alkali Metal Cations ◽  
Secondary Ion

The mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) is discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali–metal cations) of carboxylated PEGs was compared with that of non-carboxylated analogues by using both secondary-ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral analogues, PEGs. B/E linked-scan mass spectra were recorded, using secondary-ion mass spectrometry as a method for ion generation, for deprotonated and protonated molecules as well as for molecules cationised by alkali–metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxyl groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H]− ions proceeds through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain and leads to the octylphenoxyl anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative-ion mode were found to be more suitable than SI mass spectra for the determination of the average molecular weight of carboxylated ethoxylates.

scholarly journals Alkali Metal Hydride Complexes: Well-Defined Molecular Species of Saline Hydrides

2015 ◽  
Vol 68 (8) ◽  
pp. 1190 ◽  
Author(s):  
Lea Fohlmeister ◽  
Andreas Stasch
Keyword(s):  
Alkali Metal ◽  
Molecular Species ◽  
Metal Hydride ◽  
Alkali Metals ◽  
Metal Hydrides ◽  
Hydride Complexes ◽  
Ionic Solids ◽  
Hydride Elimination ◽  
Alkali Metal Hydride ◽  
Group 1

The first examples of well-defined alkali metal hydride complexes have been synthesised and characterised in recent years, and their properties and underlying principles for their generation and stabilisation are emerging. This article gives an account of the hydrides of the alkali metals (Group 1 metals) and selected ‘-ate’ complexes containing hydrides and alkali metals, and reviews the chemistry of well-defined alkali metal hydride complexes including their syntheses, structures, and characteristics. The properties of the alkali metal hydrides LiH, NaH, KH, RbH, and CsH are dominated by their ionic NaCl structure. Stable, soluble, and well-defined LiH and NaH complexes have been obtained by metathesis and β-hydride elimination reactions that require suitable ligands with some steric bulk and the ability to coordinate to several metal ions. These novel hydride complexes reward with higher reactivity and different properties compared with their parent ionic solids.

Synthesis and Characterization of Large Single Crystals of Silicon and Germanium Clathrate-II Compounds and a New Tin Compound with Clathrate Layers

2000 ◽  
Vol 626 ◽  
Author(s):  
Svilen Bobev ◽  
Slavi C. Sevov
Keyword(s):  
Alkali Metal ◽  
Single Crystals ◽  
Alkali Metals ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Alkali ◽  
Pauli Paramagnetism ◽  
Silicon And Germanium

ABSTRACTWe have synthesized large single crystals of clathrate-II compounds with frameworks of silicon and germanium by employing mixed alkali metal countercations. The combinations of alkali metals are rationally selected in order to fit the different cages of the clathrate-II structure. This approach leads to the following stoichiometric and fully “stuffed” compounds: Cs8Na16Si136, Cs8Na16Ge136, Rb8Na16Si136 and Rb8Na16Ge136. The structures and the corresponding Si-Si and Ge-Ge distances are elucidated and established with high accuracy from extensive single crystal X-ray diffraction work. The compounds are stoichiometric, metallic, and are very stable at a variety of extreme conditions such as heat, concentrated acids, hydrothermal treatment etc. No evidence was found for vacancies in the silicon and germanium networks or partial occupancies of the alkali metal sites. The stoichiometry of these fully “stuffed” clathrates is consistent with the measured temperature independent Pauli paramagnetism, supported also by the conductivity measurements on single crystals and thermopower measurements on pellets. A new compound with novel clathrate-like structure forms when small and large cations are combined with tin. The new materials, A6Na18Sn46 (A = K, Rb, Cs), are made of clathrate layers and the interlayer space filled with Sn4-tetrahedra and alkali-metal cations. Its formula can be rationalized as A6Na6Sn34 + 3·Na4Sn4 (one clathrate layer and three tin tetrahedra). The compound is stable in air and is being currently tested at other conditions. Detailed measurements of its transport properties are under way.

Hard Template Synthesis of Mesoporous and Nanocrystalline Alkali Metal Niobates with Enhanced Photocatalytic Performance

2013 ◽  
Vol 367 ◽  
pp. 12-15
Author(s):  
Qing Li ◽  
Li Ya Wang ◽  
Xiu Kai Li
Keyword(s):  
Solid State ◽  
Alkali Metal ◽  
Physical Properties ◽  
Template Synthesis ◽  
Solid State Reaction ◽  
Alkali Metals ◽  
Photocatalytic Performance ◽  
Hard Template ◽  
Single Crystalline

A nanocasting method using SBA-15 as a hard template was adopted to prepare mesoporous nanocrystalline ANbO3 (A = Li, Na, and K) samples. The characteristics of samples werecharacterized by techniques such asXRD, N2-sorption measurement, HRTEM and UVDRS. It was found that thealkality of the alkali metals could have profound impacts on the synthesis andthe physical properties of samples. The Li, Na, and K precursors can reacteasily with the siliceous template, and the reactivity varies with the alkalityof the alkali metal. The synthesis of KNbO3 is unsuccessful because of the high alkality ofK. The templated LiNbO3 andNaNbO3 consist of single crystalline nanoparticles that generate interparticle mesoporosity. The LiNbO3andNaNbO3 samples showed notably enhanced photocatalytic activitiesfor 2-propanol photodegradation in comparison to the counterparts prepared bythe solid state reaction.

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