B.B. Chaivanov

Structure of simple and complex noble gas fluorides

The structural parameters of simple and complex fluorides of noble gases in different aggregate states have been analyzed. The data on their molecular and crystal structure are reported. The structural features of simple, coordination, polymer, and clathrate-like compounds of krypton and xenon fluorides are considered

“Clathrates” (?) of noble-gas fluorides

Abstract Reactions between gold pentafluoride and alkali-earth metals fluorides in non-aqueous hydrogen fluoride were investigated. Ca(AuF 6 ) 2 , Sr(AuF 6 ) 2 and Ba(AuF 6 ) 2 were identified. The Raman spectra of the received compounds were examined in crystalline form and in the non-aqueous HF solution. It was found out, that bis-hexafluoroaurates had high solubility in non-aqueous HF. The Raman spectra of liquid system HFM II (AuF 6 )KrF 2 were investigated. The compounds of variable composition on KrF 2 , where n=1+4 (Ba, Sr) and n=1+3 (Ca) were crystallized from this system, if the solvent were evaporated slowly. The results of Raman spectra analyses of obtained compounds are presented. Interaction between KrF 2 and M II (AuF 6 ) 2 leads to essential increase of vibrational frequency of KrF bond (up to 35 cm −1 ) comparing with KrF 2 (462 cm −1 ) and to the splitting of vibrational bond. This interaction decreases with increase of n; the possible nature of interaction is discussed. The received compounds are characterized by higher thermal stability of the “bonded” KrF 2 . If heated up to 350 K KrF 2 may be quantatively obtained from the salts. If heated quickly up to 370+380 K the salts decomposes with explosion. The energy aspect of the complex salts formation is discussed. The results of interaction between M II (AuF 6 ) 2 and xenon fluorides will be also presented.

Synthesis and Spectral Properties of Hexafluoroaurates

It is established that krypton difluoride (KrF2) interacts with metallic gold in anhydrous hydrogen fluoride (HF) in the presence of alkaline and alkaline-earth metal fluorides with the formation of complex hexafluoroaurates with the general formula MIAuVF6 (MI = Li, Na, K, Rb, Cs) and bis-hexafluoroaurates MII(AuVF6)2 (MII = Mg, Ca, Sr, Ba). As a result of the subsequent interaction of bis-hexafluoroaurates with krypton difluoride, new coordination compounds with the composition MII(AuVF6)2 · nKrF2 (MII = Ca, Sr, Ba; n = 0–4) were synthesized. The Raman spectra were studied and a comparative analysis of the Raman spectra of the obtained compounds was performed. The possible variants of the structural transformation of the AuF6− anions in compounds and the position and character of the chemical bond of the “guest” (KrF2) in these compounds are discussed.

Vibrational spectra of AuF5 complexes with nitrogen fluorides and oxofluorides

Vibrational spectra and structural features of AuF5 complexes with nitrogen fluorides (NF3, N2F4) and oxofluorides (FNO, NF3O) are investigated. Vibrational frequency assignment in the solid phase and in solution of anhydrous HF was made. Distinctive features of vibrational spectra of X+AuF6− (X = NF4+, N2F3+, NO+, NOF2+) related to structural transformations of cations and hexafluoroaurate anion due to the influence of the crystal field and cation-anion interactions are discussed.

Fluorination of polysulfone

Abstract Fluorination of aromatic polysulfone film was achieved by treatment with XeF2 vapors. Swelling tests in certain industrial liquids and fuels showed substantial decrease in swelling of the fluorinated films. The influence of a catalyst on the fluorination process was examined. Results of gravimetric measurements, bulk analysis and ESCA-spectroscopy of the treated samples will be presented as well as the values of certain mechanical properties of the fluorinated films. The optimum time and conditions of the fluorination process for aromatic polysulfone film were determined.

Synthesis methods of fluorocontaining compounds

Experimental studies carried out resulted in the new methods of synthesis of inorganic fluorides,which satisfied practically by all the above mentioned demands: 1. Method of synthesis using catalytic-thermal generation of atomic fluorine from molecular fluorine. 2. Method of synhtesis using as fluorinating aqents such substances, so-called “carriers” of atomic fluorine, as O2F2 and KrF2. 3. Method of synthesis in solutions of fluor-oxidants (O2F2, KrF2, XeF2, XeF4) in non-aqueous hydrogen fluoride and bromine pentafluoride. Synthesis methods of fluorocontaining compounds, which have been developed on principally new base and has technological prototypes, make it possible to solve practically all problems of modern industries and by this provides the introduction of the whole row of inorganic fluorides in various branches of industry. 1. fluorides of high purity for microelectronic (PF5, AsF5, S2F10); 2. fluorides of high purity for optical materials; 3. chemical reagents; 4. fluorinating agents for organic chemistry (BiF5, PbF4, TbF4, CoF3, XeF2 …); 5. fluorine-ion conductive materials for solid state batteries and other tasks. The data obtained in this study are discussed together with existing data on classical methods of synthesis and the exchange one in unaqueous solvents.

Synthesis of xenon difluoride by xenon diffusion combustion in fluorine

Abstract The object of this work is an investigation of the XeF2 synthesis by diffusion combustion of previously non-mixed gaseous xenon and fluorine and creating an industrial XeF2 of effect of various parameters, including the initial conditions of a diffusion flare ignition of the xenon-fluorine systems were studied. The maximum length of the diffusion flare were determined using the following equation where m is a theoretical amount of fluorine, necessary for combustion of 1 m3 of Xe, POF and POXe — the densities of F and Xe respectively. The optimal conditions of the process were established and using them the XeF2 with the degree of purity more than 99,5 % were obtained.

Modification of polymers by inorganic fluorocontaining oxidants

Abstract The interaction between inorganic fluorocontaining oxidants, in particular, XeF 2 , KrF 2 , ClF 5 in gas phase and polyethylene (plates and foils) in the presence and absence of Lewis fluoroacids, were examined. As a result of polyethylene treatment with fluorinating agents, the surface film, which depending upon the conditions of the process, can contain up to 40% of fluorine, is formed. It was shown that the polyethylene modification is essentially influenced by conditions of the process — the duration of the treatment, fluorinating agent concentration, the temperature of the process, the type and the presence (or absence) of catalyst. The optimum conditions of polyethylene treatment were found out. The polyethylene modified by such method has better chemical resistance, the lower adhesion for some materials. The products of fluorination were identified by the following methods — gravimetry, vibrational spectroscopy (IR and Raman) and ESCA. Some other results of polymers modification, in particular, rubbers in gas phase and polymethylmetacrylate and its copolymers in organic solution will be presented.

Quasi-heterogeneous combustion of phosphorus in fluorine

Abstract The combustion of red phosphorus in fluorine under conditions of outside-diffusion inhibition at temperature range 300–623 K and total pressure up to 5.0 MPa was studied. At the present conditions the combustion has a quasi-heterogeneouse nature. The high temperature in the reaction surface layer of red phosphorus heats the deep phosphorus layers, where a red-to-white modification transition of phosphorus occurs because that there is no access of fluorine. The allotropic change of phosphorus modification in the deep layers results in the change of kinetic characteristics of the reaction: the fluorination rate sharply increases after achieving of certain degree of conversion, that is untypical for topochemical reactions. The product of phosphorus fluorination depending on the process conditions may be phosphorus pentafluoride or trifluoride or mixture of these substances. The kinetic characteristics of phosphorus fluorination by molecular fluorine in the wide range of temperatures and pressures under outside-diffusion inhibition conditions had been studied. The diffusion coefficients of reactants and gaseous reaction products and the optimal conditions of synthesis of phosphorus penta- and trifluorides had been determined.