The reaction of iodine oxide pentafluoride and rhenium oxide pentafluoride with graphite

IOF₅ intercalates into graphite accompanied by partial oxygenation of the graphite host. The intercalated species was identified by ¹⁹F nmr spectroscopy. Oxygenation of the graphite was established by analyses of the gaseous reaction products. Intercalation of ReOF₅ into graphite is accompanied by liberation of large amounts of ReF₆ and traces of COF₂ and COF₂. The oxygenation of the graphite was established by weight increase. The stoichiometry of the reactions and physical measurements indicated that the intercalated species is ReF₄ together with varying amounts of ReF₆. The formation of these fluorides from ReOF₅ can be explained in terms of an intermediate formation of ReF₅ followed by its disproportionation.     

Acetonitrile and triphenylphosphine oxide complexes of the uranium pentafluoride - antimony pentafluoride and uranium tetrafluoride oxide - antimony pentafluoride adducts

The new ternary adducts, UF₄O·SbF₅·2CH₃CN, UF₄O·2SbF₅·6L, UF₅·SbF₅· 2L (L = CH₃CN or (C₆H₅)₃PO) and UF₅·2SbF₅·5CH₃CN, have been prepared and studied by infrared, ¹⁹F n.m.r. and e.s.r. spectroscopy, mass spectrometry, X-ray powder diffraction and chemical analysis. The infrared spectra strongly suggest an ionic formulation with the uranium cationic species preferentially coordinated by the organic ligand.     

The reaction of arsenic pentafluoride with graphite fluorosulfate

The reaction of graphite fluorosulfate with an excess of arsenic(V) fluoride produces the new intercalation compound C₁₄⁺ [AsF₅(SO₃F)]^?. Identification as a first stage compound rests on the observed interlayer separation of 7.92 Å and the position of ν_E2g at 1636 cm^?1 in the Raman spectrum. Evidence for [AsF₅(SO₃F)]^? as intercalant is based on ¹⁹F NMR spectra of the solid material. C¹⁴⁺[AsF₅(SO₃F)]^? is found to exhibit high electrical conductivities in the basal plane.     

Thermal behaviour of graphite intercalation compounds with oxide of difluoride of phosphoryl

We present in this paper the thermal analysis (calorimetry, TG and DSC) of the first stage P₂O₃F₄ graphite intercalate compound in atmospheric pressure and high pressure. By heating we obtain always exfoliation phenomenon. The heating of exfoliated, graphite shows an important oxidation resistance in comparison with another exfoliated graphite. This oxidation resistance has been studied also by thermal analysis like TG, in oxygen atmosphere. Carbon foil rebuilding from exfolied graphite keeps these interesting antioxidation properties.     

Facile sonochemical synthesis of graphite intercalation compounds

[reaction: see text] Graphite intercalation compounds (GICs) are useful as powerful reducing agents in organic chemistry and are typically prepared by anaerobic solid-state reactions at high temperatures for 1-8 h. We have been able to prepare KC(8) in situ in toluene using ultrasound in less than 5 min. This allows for a convenient approach to reductive chemical syntheses involving GICs.     

X-ray photoelectron study of fluorinated graphite intercalation compounds

Intercalated compounds of fluorinated graphite C₂F·yR, where R is benzene, hexafluorobenzene, acetone, or germanium tetrachloride, are studied by X-ray photoelectron spectroscopy. The binding energies of the C1s and F1s inner levels indicate that the C-F chemical bond in fluorinated graphite differs dramatically from the covalent bond in graphite monofluoride. The binding energies of the inner levels in atoms of the graphite fluoride matrix and GeCl₄ are analyzed and it is concluded that there is no chemical binding between the host matrix and the guest molecule. Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 6, pp. 1127–1133, November–December, 1998.     

Reaction of carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride

Reaction of various carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride was investigated. Aromatic aldehyde, ketones, and α-ketoester react with xenon difluoride to give α,α-difluoroalkyl phenyl ethers. However, acid fluoride, ester, acid cyanide, α-ketocarboxylic acid, or thioester do not afford the corresponding products. In the case of cinnamaldehyde, fluorination was accompanied by intramolecular cyclization to afford fluorinated epoxide.     

Facile preparation of graphite intercalation compounds in alkali solution

Graphite intercalation compounds are often prepared by flake graphite, oxidants, inorganic acids, organic acids and intercalated ions which are usually hydrogen protons between the graphene planes. They are also known as the acid-treated graphite intercalation compounds. In this work, alkaline graphite intercalation compounds were prepared by flake graphite, K₂Cr₂O₇, concentrated H₂SO₄ and NaOH, and the morphology and structure were characterized by Electron microscopy and X-ray techniques. The results display that the combination of neutralisation heat and oxidation capability produced by K₂Cr₂O₇ can break the bonds to produce the spaces between the graphene planes and hydroxyl ions also intercalate into the graphene planes to form alkaline graphite intercalation compounds in alkali solution. The morphology and structure of alkaline graphite intercalation compounds are analogous to the ones of the acid-treated graphite intercalation compounds, but the intercalated ions and the expansion volume are different. The results show that the method is an innovation.     

Analogies and differences between calcium-based and europium-based graphite intercalation compounds

An original method using lithium-based liquid alloys has been developed, allowing studies on bulk graphite intercalation compounds with calcium and europium. We showed that binary and ternary compounds belonging to graphite-lithium-calcium and graphite-lithium-europium systems are synthesized in both cases for equivalent reaction conditions but amazingly with many different structural and physical properties. Concerning CaC₆ and EuC₆, even if their 2D unit cells are hexal, their c-axis stacking sequences lead to different symmetries. Regarding kinetical data, formation mechanisms of these graphite intercalation compounds appear comparable however different, with a first common step before differenciation in the intercalation mechanism. Obviously, their physical properties are strongly different due to the nature of the intercalated metallic element. So, the different ternary compounds from these systems also show very considerable differences concerning their electronic properties: complex magnetic ordering for Eu-based ternary GIC and superconducting behaviour for Ca-based ternary GIC. However, common points are highlighted.     

Determination of arsenic compounds by high-pressure liquid chromatography–graphite furnace atomic absorption spectrometry and thermospray mass spectrometry

Biologically important arsenic species such as arsenobetaine, arsenocholine iodide, tetramethylarsonium iodide, methylarsonic acid, and dimethylarsinic acid can be separated and quantitated by HPLC. The pH-sensitive separations on a weak anion-exchange column are described, as well as separations on a reverse-phase column with the aid of tetrabutylammonium nitrate or heptanesulfonic acid as ion-pairing agents. The thermospray mass spectra of these arsenicals in addition to those of sodium arsenate and an arsenosugar derivative are described. This technique is suitable for HPLC MS studies.     

Acceptor-type graphite intercalation compounds and new carbon materials based on them

The problems of synthesis and study of the physicochemical properties of graphite intercalation compounds (GIC) formed upon insertion of various molecules into the interplanar space of graphite are considered. Binary and ternary intercalation compounds with protonic acids (HNO₃, CH₃COOH, H₃PO₄, H₂SO₄, etc.) are described. The results of systematic research into graphite intercalation by potentiometry, calorimetry, powder X-ray diffraction, conductivity measurements, DTA, chemical analysis, and other methods are given. These results underlie elucidation of the characteristic and peculiar features of acid insertion into graphite. The physicochemical properties and practical applications of GIC and low-density carbon materials are analyzed. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1699–1716, August, 2005.     

Fe/膨胀石墨插层复合物的简易制备与电磁特性研究

以膨胀石墨和硫酸亚铁为前驱物,采用一步还原法得到Fe/膨胀石墨(Fe/EG)插层复合物.并用SEM、XRD、网络矢量分析仪等测试仪器分别研究了Fe含量(wFe)对Fe/EG插层复合物的形貌、结构、微波电磁和吸波性能的影响.结果表明:改变插层剂Fe的含量能有效地调控Fe/EG插层复合物的微波电磁与吸收特性.随wFe在27.5wt%～71.5wt%范围内增大,Fe/EG插层复合物的介电常数在wFe=27.5wt%时达到最大值,磁导率呈现多重共振现象,微波吸收性能逐渐增强.这种优异的微波吸收特性归功于Fe/EG插层复合物增强的电磁匹配和磁共振损耗.     

Thermodynamic characteristics of thermal dissociation of inclusion compounds based on graphite fluorides

Thermal dissociation processes for acetonitrile inclusion compounds based on the polymer fluorographite host matrix C₂F _x Br_0.01·yCH₃CN, where x = 0.49?C0.92, y = 0.174?C0.285, are investigated. Thermodynamic parameters (??H°_av, ??S°_av, ??G°₂₉₈) for deintercalation of the compounds of the first filling step into the compounds of the second step and gaseous guest within temperature range 294?C352 K were determined. The effect of the host matrix fluorination degree on the thermodynamic characteristics of the studied processes is demonstrated.     

Thermodynamics of graphite intercalation binary alloys of Li-Na,Na-K,and Li-K from van der Waals density functionals

Journal of Solid State Electrochemistry - Graphite may store lithium or potassium, but not sodium, in its interlayer space under ambient conditions. It is, however, unclear whether binary alkali...     

Mass spectrometry studies of organolead compounds

The mass spectra of alkyl‐, aryl‐ and chlorinated ‐alkyl, aryl organolead compounds were investigated. Positive and negative ion mass spectra of these compounds were recorded using conventional electron impact conditions. In common with the analogous tetraalkyltin and tetraalkylgermanium compounds, tetrabutyllead produced no negative ion spectra under these conditions. The spectra were also examined by tandem mass spectrometry in order to establish reaction mechanisms for these compounds. Fragmentation patterns of seven organolead compounds, based on precursor–product ion relationships, are proposed. Copyright © 2001 John Wiley & Sons, Ltd.     

Synthesis of ternary and quaternary graphite intercalation compounds containing alkali metal cations and diamines

A series of ternary graphite intercalation compounds (GICs) of alkali metal cations (M = Li, Na, K) and diamines [EN (ethylenediamine), 12DAP (1,2-diaminopropane), and DMEDA (N,N-dimethylethylenediamine)] are reported. These include stage 1 and 2 M-EN-GIC (M = Li, d(i) = 0.68-0.84 nm; M = Na, d(i) = 0.68 nm), stage 2 Li-12DAP-GIC (d(i) = 0.83 nm), and stage 1 and 2 Li-DMEDA-GIC (d(i) = 0.91 nm), where d(i) is the gallery height. For M = Li, a perpendicular-to-parallel transition of EN is observed upon evacuation, whereas for M = Na, the EN remains in parallel orientation. Li-12DAP-GIC and Li-DMEDA-GIC contain chelated Li(+) and do not show the perpendicular-to-parallel transition. We also report the quaternary compounds of mixed cations (Li,Na)-12DAP-GIC and mixed amines Na-(EN,12DAP)-GIC, with d(i) values in both cases between those of the ternary end members. (Li,Na)-12DAP-GIC is a solid solution with lattice dimensions dependent on composition, whereas for Na-(EN,12DAP)-GIC, the lattice dimension does not vary with amine content.     

Synthesis,properties, and structure of intercalated graphite fluosulfonate fluorides

Graphite fluosulfonate fluorides of the composition C₂F_x−y(SO₃F)_y (x+y≈1) have been synthesized. The new compounds can be treated as derivatives of graphite fluorides C₂F_x(x≈1) in which approximately 1/50 of the F atoms have been replaced by SO₃F groups. The intercalates based on the new matrices have been studied by X-ray phase analysis, IR spectroscopy, mass spectrometry, and thermography. The ability of the intercalates to absorb various substances is investigated. It is shown that the introduction of a few SO₃F groups into the C₂F_x matrices significantly changes the physicochemical properties and the structure of intercalates; in particular, for intercalates of stage II structure this expands the scope of substances that can penetrate into interlayer spacings. The dependence of the penetration ability of the substances on the van der Waals sizes of their molecules makes intercalates resemble zeolites in properties. Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Novosibirsk. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No, 1, pp. 144–151, January–February, 1995 Translated by I. Izvekova     

Reactions of xenon difluoride. Part 6. Some reactions of phosphorus,arsenic and iodine compounds

The reaction of XeF₂ with some organo-phosphorus, -arsenic and-iodine compounds is described. The products were identified by fluorine nmr spectroscopy and the conditions under which fluorine exchange occurs were briefly investigated. Organoiodine (III) difluorides are suitable for the conversion of Ph₂Te to Ph₂TeF₂; the decomposition of RIF₂liberates IF and fluoroalkane.