Hexafluoroarsenate preparation

Hexafluoroarsenic acid [17068-85-8] can be prepared by the reaction of arsenic acid with hydrofluoric acid or calcium fluorosulfate (29) and with alkaH or alkaline-earth metal fluorides or fluorosulfonates (18). The hexafluoroarsenates can be prepared directly from arsenates and hydrofluoric acid, or by neutrali2ation of HAsF. The reaction of 48% HF with potassium dihydrogen arsenate(V), KH2ASO4, gives potassium hydroxypentafluoroarsenate(V)... 

Arsenic trifluoride (arsenic(III) fluoride), AsF, can be prepared by reaction of arsenic trioxide with a mixture of sulfuric acid and calcium fluoride or even better with fluorosulfonic acid. Chlorine reacts with ice-cold arsenic trifluoride to produce a hygroscopic soHd compound, arsenic dichloride trifluoride [14933-43-8] ASCI2F35 consisting of AsQ. and AsF ions (21). Arsenic trifluoride forms a stable adduct, 2AsF2 SSO, with sulfur trioxide and reacts with nitrosyl fluoride to give nitrosonium hexafluoroarsenate(V) [18535-07-4] [NO][AsFg]. 

The dinitrobenzyl tosylate, (15) triphenylsulfonium hexafluoroarsenate (16), and triphenylsulfonium triflate (17) were prepared as described in the literature. The monomers, 4-t-butoxycarbonyloxy-a-methylstyene (t-BOC-a-methylstyrene), and 4-t-butoxycarbonyloxystyrene (t-BOC-styrene) and their respective homopolymers, TBS and TBMS were prepared as described in the literature (12,14). TBSS was prepared by conventional, free-radical methods (13,18). The composition of this polymer (ratio of SO2 to t-BOC styrene) is controlled by changing the polymerization temperature and/or initiator concentration (Table II). 

There are a few reports of poly(naphthalene) thin films. Yoshino and co-workers. used electrochemical polymerization to obtain poly(2,6-naphthalene) film from a solution of naphthalene and nitrobenzene with a composite electrolyte of copper(II) chloride and lithium hexafluoroarsenate. Zotti and co-workers prepared poly( 1,4-naphthalene) film by anionic coupling of naphthalene on. platinum or glassy carbon electrodes with tetrabutylammonium tetrafluoroborate as an electrolyte in anhydrous acetonitrile and 1,2-dichloroethane. Recently, Hara and Toshima prepared a purple-colored poly( 1,4-naphthalene) film by electrochemical polymerization of naphthalene using a mixed electrolyte of aluminum chloride and cuprous chloride. Although the film was contaminated with the electrolyte, the polymer had very high thermal stability (decomposition temperature of 546°C). The only catalyst-free poly(naphthalene) which utilized a unique chemistry, Bergman s cycloaromatization, was obtained by Tour and co-workers recently (vide infra). 

Glemser and Smalc798 have prepared the compound Br 1 AsFfi by the displacement of oxygen in dioxygenyl hexafluoroarsenate by bromine [Eq. (4.196)] and by the reaction of bromine pentafluoride, bromine, and arsenic pentafluoride [Eq. (4.197)]. The compound is chocolate-brown and in solution has absorption bands at 310 nm and 375 nm it has fair thermal stability and can be sublimed at 30-50°C under nitrogen atmosphere. 

The C)2 1 Sh2I i i was converted to 02+SbI fi by heating at 130°C in vacuo conversely, 02+Sb2Fn- was prepared by reaction of 02 1 SbFfi and SbF5 at 180-200°C. Dioxygenyl hexafluoroarsenate is markedly less stable than the hexafluoroantimonate salts it decomposes rapidly at 130-180°C. 02 1 PtF(, can be sublimed above 90°C in vacuo and melts with some decomposition at 219°C in a sealed tube.863... 

Hexafluoroarsenate salts 74 and 75 are prepared from the relevant nitriles using S2NAsF6 as the source of the dithianitronium cation (SNS+). Further reaction with 2equiv of SbPh3 gives radicals 76 and 77. Such reactivity can be confirmed by ESR spectroscopy, prior to quantitative isomerism, which takes place at room temperature <1986CC140>. 

Se2Br5+, as the first reported example of a novel dinuclear cationic halogen-chalcogen species, was prepared as the deep-purple crystalline hexafluoroarsenate. The cation consists of two trigonal pyramidal SeBrs units connected via a linear Se-Br-Se bridge. The formally positive Br+ links two SeBr2 molecules with formal oxidation number - -2 for Se. 

Glemser and Smalc (15) have prepared the compound Brg+AsFg" by the displacement of oxygen in dioxygenyl hexafluoroarsenate by bromine [Eq. (12)] and by the reaction of bromine pentafluoride,... 

Hexafluorobenzeae and Octafluorotolueae Hexafluoroarsenates(V). The bright yellow monocyclic cation hexafluoroarsenates were typically prepared (eq 17) by co-c[Pg.23]

As the cofacial dimer 1 is a readily available compound, the best method for the preparation of thiatriazinium salts is to treat 1 with nitrosyl tetrafluoroborate or hexafluorophosphate. The reaction mixture must be kept under inert gas during the evolution of nitrogen oxide. A direct method is the reaction of 1-fluorothiatriazines, e.g. 3, with arsenic(V) fluoride or phosphorus pentafluoride. The so-called silver salt method consists of the reaction of 1-chlorothia-triazincs with silver(I) hexafluoroarsenate in liquid sulfur dioxide. 

The compound [AsC14][AsF6] can be used for the preparation of other hexafluoroarsenates, particularly those involving nonmetallic cations. The following preparations may be mentioned (113) ... 

Fluorodiazonium hexafluoroarsenate ( — = N AsFg" a white solid) was first prepared by Moy and Young (1965) by fluoride ion abstraction from (Z)-difluorodiazene by ASF5 at low temperature (3-14) (see also Bormann and Glemser, 1966 Pankratov and Savenkova, 1968). Christe et al. (1991) prepared the corresponding hexafluoroantimonate salt FN SbFg . 

Dioxygenyl hexafluoroarsenate can be prepared by the reaction between arsenic pentafluoride and dioxygen difluoride or by heating a mixture of arsenic pentafluoride, fluorine, and oxygen. However, photosynthesis, using this latter mixture, appears to be the most convenient method for the preparation of dioxygenyl hexafluoroarsenate. 

Peroxydisulfuryl fluoride is usually synthesized by catalytic fluorination of sulfur trioxide.However, pure peroxydisulfuryl fluoride can be obtained in a relatively simple way by the reaction between fluorosulfuric acid and dioxygenyl hexafluoroarsenate. The method lends itself to preparation of smaller quantities (a few grams) of peroxydisulfuryl fluoride. The reaction can be carried out in an openable nickel or Monel pressure vessel, into which dioxygenyl hexafluoroarsenate is transferred from a photochemical reactor (see the preceding synthesis of dioxygenyl hexafluoroarsenate) or, more simply, in the same Pyrex-glass flask in which dioxygenyl hexafluoroarsenate has previously been synthesized. 

The recent interest in nitryl hexafluoroarsenate, [N02][AsFJ, as an oxidizing agent has emphasized the need for a simple, one-step, high-yield synthesis of fliis compound. Previous syntheses have involved the initial preparation of NOjF and subsequent reaction with AsF, the use of HF with HNO3, ClNOj, or nitrate esters the reaction of NOj, BrFj, and S2Of the use of PNOj " or metathetical reactions from other [AsF ] salts. These reactions generally are conducted in metal cylinders or quartz vessels. The method reported here involves the direct reaction of NO2, Fj, and AsFj in a Pyrex vessel and provides a pure product. 

Frohn and coworkers have reported the preparation of a perfluoroaryliodonium salt, (C6F5)2l+AsF6, by the electrophilic arylation of CeFsI with a stable pentafluorophenylxenonium hexafluoroarsenate, CeFsXe AsFe [398]. 

Polyselenophene (Fig. 16c) has been prepared. However, due to the difficulty in obtaining the monomer, the polymer has not been extensively investigated. Polymers of selenophene prepared electrochemically under appropriate conditions yield films with maximum conductivities of 10"- S cm [330,331]. Samples of p-doped selenophene produced chemically have conductivities on the same order of magnitude [332]. Applying 3-10 V between two electrodes in an electrolyte of 0.1 to 1 M lithium tetrafluoroborate or lithium perchlorate dissolved in benzonitrile or propylene carbonate gives polyselenophene films, as does the combination of tetrabutylammonium tetrafluoroborate in benzonitrile. However, other salts such as lithium hexafluoroarsenate, lithium hexafluorophosphate, tetrabutylammonium perchlorate, or silver perchlorate in combination with solvents such as acetonitrile or nitrobenzene were reported to produce either powders or no products at all [330,331,333]. 

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