Halide compounds thermodynamics

Binary Systems and Related Compounds.—Halides. The thermodynamics of gas-phase equilibria in the W-F2 and W-F2-H2 systems at high temperatures have been described.The Raman spectrum of solid MoF exhibits Mo—F stretching bands at 746, 722, and 690 cm These results suggest that the compound has a similar structure to NbF4, with each molybdenum co-ordinated to six fluorine atoms.The Raman spectrum of crystalline M0F5 has also been reported and interpreted in terms of the crystal structure.The electronic spectrum of liquid M0F5 has been determined and shown to be consistent with a trigonal-bipyramidal molecular unit. ... 

Compounds with sulphur are called fluorides. Apart from its fluorides, nitrogen halides are thermodynamically unstable and very explosive. The trifluroide NF3 can be prepared by direct reaction of... 

Ionova GV (2002) Thermodynamic properties of halide compounds of tetravtilent transactinides. Russ Chem Rev 71 401-416... 

Comparable recent detailed reviews of the actinide halides could not be found. The structures of actinide fluorides, both binary fluorides and combinations of these with main-group elements with emphasis on lattice parameters and coordination poly-hedra, were reviewed by Penneman et al. (1973). The chemical thermodynamics of actinide binary halides, oxide halides, and alkali-metal mixed salts were reviewed by Fuger et al. (1983), and while the preparation of high-purity actinide metals and compounds was discussed by Muller and Spirlet (1985), actinide-halide compounds were hardly mentioned. Raman and absorption spectroscopy of actinide tri- and tetrahalides are discussed in a review by Wilmarth and Peterson (1991). Actinide halides, reviewed by element, are considered in detail in the two volume treatise by Katzet al. (1986). The thermochemical and oxidation-reduction properties of lanthanides and actinides are discussed elsewhere in this volume [in the chapter by Morss (ch. 122)]. 

Halides. Xenon duorides, xenon oxide tetraduoride [13774-85-1XeOE, and their complexes are the only thermodynamically stable xenon compounds. Xenon diduo ride [13709-36-9] xenon tetraduoride [13709-61-0], and xenon hexaduoride [13693-09-9] are colodess, crystalline soHds which can be sublimed under vacuum at 25°C. The mean thermochemical bond energies are XeE2, 132.3 0.7 kJ/mol (31.6 0.2 kcal/mol) XeE ... 

The above data are correct to about 20 kJ mole but it will be seen that the general trend among these more covalent bonds does appear to be a decrease in stability from carbon to silicon, i.e. the same way as was found for more ionic bonds in the halides. Thermodynamic data for metallorganic methyl compounds used in the produchon of semiconductor systems are shown in Table 2.3. 

The third aspect, the stability range of solid electrolytes, is of special concern for alkaline-ion conductors since only a few compounds show thermodynamic stability with, e.g., elemental lithium. Designing solid electrolytes by considering thermodynamic stability did lead to very interesting compounds and the discovery of promising new solid electrolytes such as the lithium nitride halides [27]. However, since solid-state reactions may proceed very slowly at low temperature, metasta-... 

A critical assessment of the chemical thermodynamic properties of the actinides and their compounds is presently being prepared by an international team of scientists under the auspices of the International Atomic Energy Agency (Vienna). As a result of this effort, four publications (1, 2, 3, 5) have already become available and a further ten 6-T4), including the halides (8) and aqueous complexes with Tnorganic ligands (12),... 

In spite of well identified deficiencies, the status of the existing thermodynamic data on solid halides and related compounds is rather satisfactory. By contrast, the data on aqueous halogeno-complexes are fragmentary, sometimes contradictory and in most cases limited to stability constants in such a context, recommendation of best values can be made for a few species only. 

This reaction is a principal method of forming IIIB-transition-metal cr bonds. The formation of thermodynamically favored alkali-metal halides or related salts and acids HX enhances the easy formation of those bonds. A second possible interaction between anionic metal bases and group-IIIB halides is a simple acid-base relationship without elimination of halide anions. However examples of this are rare, and they have been described often for group-IIIB compounds without halogen ligands ( 6.5.3.2). 

Unlike the di-f dihalides, such compounds differ little in energy from both the equivalent quantity of metal and trihalide, and from other combinations with a similar distribution of metal-metal and metal-halide bonding. So the reduced halide chemistry of the five elements shows considerable variety, and thermodynamics is ill-equipped to account for it. All four elements form di-iodides with strong metal-metal interaction, Prl2 occurring in five different crystalline forms. Lanthanum yields Lai, and for La, Ce and Pr there are hahdes M2X5 where X=Br or I. The rich variety of the chemistry of these tri-f compounds is greatly increased by the incorporahon of other elements that occupy interstitial positions in the lanthanide metal clusters [3 b, 21, 22]. 

Addition of Bu3SnLi or McsSnI.i to 4-t-butylcyclohexanone affords mixtures of trans and cis adducts in ratios that depend on reaction conditions (Table ll)68. In THF, a 93 7 mixture is obtained with both reagents. This ratio is thought to represent the thermodynamic distribution—the axial stannane being favored. In ether, the cis isomer predominates, suggesting a kinetic preference for equatorial addition. Each of the two isomers can be lithiated with BuLi. Subsequent treatment with alkyl halides or carbonyl compounds affords the substituted alkoxy cyclohexanes with retention of stereochemistry. 

Because of the particular structural features of compound 4, pointed out in Section I, the D-glucofuranosyluronic halide anomers not only have inverse thermodynamic stabilities with respect to those of D-glucopyranosyl halides but also show a different behavior towards alcohols. For instance, 2,5-di-O-acyl-a-D-gluco-furanosylurono-6,3-lactone halides, which are difficult to prepare, do not react with alcohols, inasmuch as an endo approach of the reagent is inhibited.14 The /3-bromides and -chlorides, however, just like /3-D-glucopyranosyl chlorides, are subject to alcoholysis, with formation of /3-D-glucofuranosidurono-6,3-lactones.16... 

At all temperatures above 0°K Schottky, Frenkel, and antisite point defects are present in thermodynamic equilibrium, and it will not be possible to remove them by annealing or other thermal treatments. Unfortunately, it is not possible to predict, from knowledge of crystal structure alone, which defect type will be present in any crystal. However, it is possible to say that rather close-packed compounds, such as those with the NaCl structure, tend to contain Schottky defects. The important exceptions are the silver halides. More open structures, on the other hand, will be more receptive to the presence of Frenkel defects. Semiconductor crystals are more amenable to antisite defects. 

Although pyrrolyl halides are well-known compounds, their instability to acid, alkali, and heat precludes their commercial availability. Since pyrrole is a very reactive, Jt-excessive heterocycle, it undergoes halogenation extremely readily [6, 7], For example, the labile 2-bromopyrrole, which decomposes above room temperature, is a well-known compound, as are A-aIkyl-2-halopyrroles, readily prepared by direct halogenation, usually with NBS for the synthesis of bromopyrroles [8, 9], The 2-halopyrrole is usually the kinetic product but the 3-halopyrrole is often the thermodynamic product, and this property of halopyrroles can be exploited in synthesis. For example, A-benzylpyrrole (1) can be dibrominated to give 2 as the kinetic product, which rearranges to 3 upon treatment with acid [10, 11]. Other A-alkyl-2,5-dibromopyrroles are available in this fashion. 

George, J. W., Halides and Oxyhalides of the Elements of Groups Vb and Vlb George, Philip and McClure, Donald S., The Effect of Inner Orbital Splitting on the Thermodynamic Properties of Transition Metal Compounds, and 2 33... 

In the early part of this century, many types of solid electrolyte had already been reported. High conductivity was found in a number of metal halides. One of the first applications of solid electrolytes was to measure the thermodynamic properties of solid compounds at high temperatures. Katayama (1908) and Kiukkola and Wagner (1957) made extensive measurements of free enthalpy changes of chemical reactions at higher temperatures. Similar potentiometric measurements of solid electrolyte cells are still made in the context of electrochemical sensors which are one of the most important technical applications for solid electrolytes. 

Binary Compounds. The thermodynamics of the formation of HfCl2, of HfCl4, fused sodium and potassium chlorides have been described. The reduction of ZrXj (X = Cl, Br, or I) with metallic Zr or A1 in molten AICI3 has been studied at temperatures from 250 to 360 °C, depending on the halide. The electronic spectra of the initial reaction products were consistent with either a solvated Zr complex or an intervalence Zr "-Zr" species. Further reduction resulted in the precipitation of reduction products which were identified by analysis and i.r., electronic, and X-ray powder diffraction spectra. The stability of the trihalides with respect to disproportionation was observed to increase from chloride to iodide thus ZrC and ZrCl2,0.4AlCl3 were precipitated, whereas only Zrlj was formed. ... 

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