III Oxyfluoride

Indium(III) oxyfluoride is a white crystalline solid which is practically insoluble in all ordinary solvents. It is not hydrolyzed in water at room temperature over a period of 24 hours, and it can be recovered unchanged from boiling water after 1 hour. The pure product was found to decompose at 340°C. in air to yield indium(HI) oxide. It is stable to higher temperatures (1100°C.) under an inert atmosphere or in vacuum. 

The electrical resistivity data on crystals of indium(III) oxyfluoride indicate a nearly temperature independent conductor (3.6 X 10 2 fl-cm. at room temperature and 1.8 X 10-2 fl-cm. at liquid-helium temperature) with high negative thermoelectric power (—230 juV./°C.). These properties are similar to those observed for some conductive forms of indium(III) oxide. 

III) oxyfluoride transfers fluorine to the reactant and gets converted to inactive Cr (III) oxychloride. The active catalyst is continuously regenerated from Cr (III) oxychloride state by constant supply of AHF. 

Oxidative coupling of aryl tetrahydroisoquinolines. This reagent is superior to thallium(III) trifluoroacetate or vanadium oxyfluoride for nonphenolic oxidative coupling of substrates such as 2 to provide aporphines and homoaporphines (3). 

Bismuthonium ylides, 4 34 Bismuth(III) oxide, 4 23-24 Bismuth oxide(l l), 4 23 Bismuth oxide(l 2), 4 23 Bismuth oxide(2 4), 4 23 Bismuth oxide(3 5), 4 23 Bismuth oxide(4 9), 4 23 Bismuth oxide halides, 4 23 Bismuth oxides, 4 23-24 Bismuth oxybromide, 4 23 Bismuth oxychloride, 4 23 physical properties of, 4 20t pigment used in makeups, 7 836t Bismuth oxyfluoride, 4 23 Bismuth oxyiodide, 4 23 Bismuth pentafluoride, 4 22 physical properties of, 4 20t Bismuth phosphate, 4 25... 

The oxyfluorides of La(III) and Y(III) also contain (67, 142, 143) octacoordi-nated metal ions (MO4F4), the metal ions being situated between layers of oxygen and fluorine (cf. other oxyhalides). Zachariasen [142) was able to obtain both rhombohedral and tetragonal modifications for La and Y oxyfluorides with the following M—0 and M—F distances. 

Numerous reactions have been reported in which FCIO2 is formed as a product. Most of these involve the interaction between a chlorine fluoride or oxyfluoride with an oxide or hydroxide. The oxidation state of the chlorine fluoride is not important since +1, -l-III, and - -V compounds all yield FCIO2 owing to the tendency of the lower oxyfluorides, such as FCIO, to disproportionate. The presence of excess chlorine fluoride is important to avoid formation of chlorine oxides. The following equations are typical examples for these types of reactions ... 

Chloryl fluoride, like most of the other known chlorine fluorides and oxyfluorides, possesses amphoteric character. Owing to its weak and polar (p—jr )a Cl—F bond (see Section II, C), it exhibits a much stronger tendency to form adducts with Lewis acids than with Lewis bases. The adducts with Lewis acids result in salts containing ClOg" cations, and those with bases result in ClOgFj" salts. Both ions are discussed in detail in Sections III, G and H, respectively. 

The disproportionation of chlorofluoromethanes is also catalyzed by iron(lll) halides,21 chromium oxyfluorides and other metal halides. With tron(III) chloride on activated carbon at temperatures above 300 C, for example, the compounds carbon Iclrafluoride, chloro-fluoromethane, trtchlorofluoromclhanc and carbon tetrachloride are obtained from dichloro-fluoromethane (Scheme 3) ... 

Since all these materials have a certain solubility in the electrolyte, some contamination of the metal will occur. The Eltech Systems Corporation announced [246,247] a method to protect the substrate anode material by forming a Ce(IV) oxyfluoride layer on the anode. The protective layer is maintained by adding a Ce(III) compound to the electrolyte. However, cerium contaminates the aluminum metal so that it must be removed and recirculated to the electrolyte. 

In the case of alloys, we will consider, in turn, metal oxides, metal chalcogenides and, finally, Group III-V semiconductors. We have seen earlier (Sections 6.3 and 7) how non-metallic elements such as F, N and S can alloy with the metal oxide lattice, these species occupying anion sites within the host framework. The corresponding oxyfluoride, oxynitride and oxysulfide compounds are thus generated (Section 7). 

As noted earlier Th(iii) is known only in the solid state, in ThCla, ThBr3, and Th2S3 (Table 28.2), and oxyfluorides. The latter include ThOF (statistical fluorite structure) and ThOo.sF2.s (superstructure of LaF3 type),... 

Other oxidants like thallium(III) oxide, vanadium(V) oxyfluoride, palladium ) acetate, and ruthenium(IV) tetrakis(trifluoracetate) have been developed as powerful tools for the intramolecular biaryl coupling reaction [7,93,113]. Nevertheless, DDQ is still one of the most versatile reagents in oxidative coupling reactions (see Scheme 14 and 29 [82,114]). The highly strained dioxa[8](2,7)pyrenophane (65), portraying an overall curvature of nearly 90° for the pyrene subunit, was finally obtained from the mefa-cyclophanediene (66) by dehydrogenation with DDQ in refluxing benzene in 67% yield [114]. 

During the fusion of ammonium hydrogen fluoride with pure vanadium (III) oxide the yellow fumes reported by Long and Wilhelm were not observed. However, yellow fumes were obtained on heating the acid fluoride with vanadium(V) oxide. This indicates that their vanadium (III) oxide was contaminated with pentoxide. Vanadium (V) oxide probably is converted to the pentafluoride, which is reported to react with moist air to form yellow oxyfluorides. ... 

The focus here will be on anhydrous HCl, since, (i) it is a strong Br0nsted acid (at least in water), (ii) in principle it can behave as a Brpnsted acid by dissociative adsorption at a surface that contains oxide (hydroxide) functioning as a Br0nsted base and (iii) it could function as a weak Lewis base as a result of associative adsorption at a surface that contains (strong) Lewis acid sites. From this analysis, it would be expected that the behaviour of HCl towards fluorides would be different from its behaviour towards oxides. This comparison is less clear cut however if oxyfluorides and partially hydrolysed (hydroxylated or hydrated) fluoride surfaces are included. Schematic representations of dissociatively adsorbed HCl at medium strong and weak Lewis acid sites of 7/-alumma are shown in Figures 4.6 and 4.7. These are based on spectroscopic observations. 

The Ce-Ca based oxyfluorides were prepared by coprecipitation performed in a basic medium at pH > 12. The starting materials are Ce(III) nitrates and Ca chlorides. Yamashita et al have already explored this route but only in the case of Ce-Ca based oxides. In our case, the pH, which is a key parameter, was adjusted taking into account... 

As stated in Section 11.2.4, HFC-125 is industrially produced by heterogeneous continuous vapor phase fluorination of tetrachloroethylene over chromium oxyfluoride and allied catalysts at elevated temperature [72], Chromium oxyfluoride is generated by treating chromium (III) oxide with AHF. Cr... 

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