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Resin-bound hexafluorophosphate is found to be a greener and more efficient catalyst for the title reaction than NaPF6 itself.

A simple in situ solvent formation microextraction (ISFME) method based on use of ionic liquid (IL) as extractant solvent and sodium hexafluorophosphate (NaPF6) as ion-pairing agent was proposed for the concentration of trace levels of zinc. In this method, zinc ion was complexed with 1-(2-hydroxynaphtalene-1-yl)ethane oxime (HNEO) and extracted into an ionic liquid phase. After phase separation, the enriched analyte in the final solution was determined by flame atomic absorption spectrometry (FAAS). ISFME is a fast, simple and suitable method for extraction and concentration of inorganic such as metal ions from sample solutions containing a high concentration of salts. The influences of the analytical parameters on the microextraction efficiency were investigated and optimized. Under the optimum conditions, the limit of detection and the enhancement factor were 0.05 µg L-1 and 81, respectively. The relative standard deviation (R.S.D.) was obtained 0.8%. The accuracy of the method was confirmed by analyzing certified reference materials. The presented method was successfully applied for the determination of zinc in water samples. Um método simples de microextração com formação de solvente in situ (ISFME) baseado no uso de líquido iônico (IL) como solvente extrator e hexafluorofosfato de sódio (NaPF6) como agente par-iônico foi proposto para a concentração de níveis de traço de zinco. Neste método, o íon zinco foi complexado com 1-(2-hidroxinaftaleno-1-il)etano oxime (HNEO) e extraído em uma fase líquida iônica. Após a separação, o analito enriquecido na fase final foi determinado por espectrometria de absorção atômica de chama (FAAS). ISFME é um método rápido, simples e adequado para extração e concentração de inorgânicos tais como íons metálicos em soluções contendo uma elevada concentração de sal. As influências dos parâmetros analíticos na eficiência da microextração foram investigadas e otimizadas. Sob condições otimizadas, o limite de detecção e o fator de enriquecimento foram 0,05 µg L-1 and 81, respectivamente. O desvio padrão relativo (R.S.D.) obtido foi 0,8%. A exatidão do método foi confirmada pela análise de materiais de referência certificados. O método apresentado foi aplicado com êxito na determinação de zinco em amostras de zinco.

The Na+PF6− salt changes the course of reactions between neutral or ionic substrates. Examples of reactions include superoxide radical chemistry, disproportionation, and C[sbnd]H and C[sbnd]O bond activation. This special salt effect is usually quantitative and sometimes catalytic. When compared to other salts, Na+PF6− by far gives the most spectacular results, due to the small size of Na+ as compared to large organometallic cations.

Reaction of the ligand α,α′-bis(N-1,4,7-triazacyclononane)-m-xylene (XYL-tacn) with copper(II) chloride and sodium hexafluorophosphate in acetonitrile/methanol leads to the assembly of a remarkable tetranuclear copper(II) complex. The crystal structure and magnetic properties of the novel tetranuclear Cu(II) complex are reported. The complex exhibits an unusual [(CuCl)4(μ-Cl)2] binding mode with a Cu··· Cu distance of 6.856(3) A.

Sodium hexafluorophosphate, perchlorate and trifluoroacetate were applied as ion-ion interaction reagents in reversed-phase liquid chromatography. The separation of chosen alkaloids was performed by changing the kind of the organic modifier (methanol, acetonitrile, tetrahydrofuran), concentration of the ion-ion-interaction reagents and the concentration of phosphate buffer at constant pH (2.7) in the mobile phase. Obtained results were analyzed in connection to a dynamic ion-exchange model of retention and ion-ion interaction effects. The perturbation method was applied to test proposed retention theories. The formation of ion-complexes controlling the retention in chaotropic systems was confirmed. On the basis of the relationships of capacity factors (k) versus salt concentrations derived experimentally, absolute increases in capacity factors, the desolvation parameters and the limiting retention factors were calculated and compared for all the investigated compounds in eluent systems studied. The selectivity of the proposed mobile phases was compared on the basis of the separation of alkaloid mixture.

Actuation of polypyrrole in aqueous sodium hexafluorophosphate solution has been shown to produce relatively large strains. However little has been published on appropriate potential range of actuation in this electrolyte. This information is clearly crucial for applications. Our particular interest is in disposable applications where a relatively small number of cycles are needed, and maximum strain is desired. The electrochemical degradation as a function of voltage is investigated by cycling the film between fixed voltages and measuring the charge transfer. The experiment was done on a glassy carbon substrate in order to reduce effects of change in resistance with oxidation state, preventing actuation. The dependence of charging on voltage and the rate of reduction in the extent of charging are measured. The voltage range for effective operation of the device was found to be -0.4 V to 0.8 V versus a Ag/AgCl reference electrode in order to achieve stable performance over at least 30 minutes. The mechanisms of degradation at potentials beyond 0.8 V appear to be the substitution of hydroxyl ions in the polymer backbone, as suggested in reports on degradation of polypyrrole in other electrolytes. An observed reduction in charge transfer rate at potentials lower than -0.4 V is consistent with a reduction in ionic conductivity at highly reduced states, as has also been suggested in the literature. Copyright 2007 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

The reaction of 1-n-butyl-3-methylimidazolium chloride (BMIC) with sodium tetrafluoroborate or sodium hexafluorophosphate produced the room temperature-, air- and water-stable molten salts (BMI+)(BF4−) (1) and (BMI+)(PF6−) (2), respectively, in almost quantitative yield. The rhodium complexes RhCl(PPh3)3 and [Rh(cod)2][BF4] are completely soluble in these ionic liquids and they are able to catalyse the hydrogenation of cyclohexene at 10 atm and 25°C in a typical two-phase catalysis with turnovers up to 6000.

The structure of sodium hexafluorophosphate monohydrate, NaPF(6) x H(2)O, has been inadvertently redetermined, revealing that the previously reported space group, Imma, was assigned incorrectly, with the a and b axes interchanged. The correct space group is Pnna. The program PLATON [Spek (2003). J. Appl. Cryst. 36, 7-13] suggested both Imma and Pmma as possible space groups, but only Pnna is consistent with the systematic absences. The inter-ionic and hydrogen-bonding interactions in the lattice form a three-dimensional network.

Alkali ketal salts of perfluorinated complex anions were used to effect halogen-exchange fluorination in organohalosilanes both in the presence and absence of solvent. By the use of salts of perfluorinated «non-nucleophilic» anions in a high-boiling multifunctional etheral solvent, organofluorosilanes have been conveniently prepared in high yields

cis-[(dppm)2Cl2Ru], 1 (dppm  Ph2PCH2PPh2) reacts with HCCCH(OH)R and NaPF6 to give secondary allenylidene complexes trans-[(dppm)2ClRuCCCHR][PF6], 3 [R  Ph (a), p-Ph Cl (b), p-PhOMe (c), or trans-CHCHPh (d)]. Complex 3a treated with NaBH4 gives trans-[(dppm) 2ClRuCCCH2Ph], 6a and the reaction of 3a–c with MeONa in MeOH affords trans-[(dppm)2(H) RuCCCH(OMe)R], 7a–c.

In this paper, miniaturized achiral and chiral high-performance liquid chromatographic procedures for the determination of methamphetamine and amphetamine in human urine are described. After a simple pretreatment of human urine (i.e., 10 microL of urine or diluted urine were acidified and dried-up under N2 at room temperature) and fluorescence derivatization with 4-(4,5-diphenyl-1H-imidazol-2-yl)-benzoyl chloride under mild conditions (pH 9.0, 10 min at room temperature), the derivatives were isocratically separated on a semi-micro ODS column with Tris-HCl buffer (0.1 M, pH 7.0): acetonitrile (45 + 55 v/v) at a flow rate of 0.2 mL/min or their enantiomers were separated on a semi-micro OD-RH column with sodium hexafluorophosphate (0.3 M aq.): acetonitrile (44 + 56 v/v) at a flow rate of 0.1 mL/min as the mobile phase. Wide-ranged calibration curves were obtained with detection limits for the achiral and chiral analyses in the atto and femtomol levels, respectively, per injected volume. Satisfactory within- and between-day reproducibility data were obtained with both the methods with the highest relative standard deviation being 9.6%. The methods were applied to the determination of methamphetamine and amphetamine in human urine samples and the concentrations determined by the two methods were well correlated (r = 0.994).

Crown ether complexes formed by sodium hexafluorophosphate with dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8) were synthesized and their crystal structures determined by single crystal X-ray analyses. The complex with DB18C6 consists of [Na(DB18C6)(H2O)]+ cations, free DB18C6 ligand and PF6− anions (compound 1). The sodium cation interacts with the six oxygen atoms of the crown ether and with the oxygen atom of the water molecule, which forms short contacts also with the free DB18C6 molecule. The compound with DB24C8 (compound 2) consists of [Na(DB24C8)]+ cations and PF6− anions. The sodium atom is linked to the eight oxygen atoms of the DB24C8 macrocycle, whereas the fluorine atoms of the hexafluorophosphate anions do not interact with the sodium atom.

Continuing systematic study on the alkali metal complexes with the different dibenzo crown ethers in order to determine the conformation of the ligand ring and also the coordination of the different metal cations, crystal structure of sodium hexafluorophosphate complexes with dibenzo-18-crown-6 (1) and dibenzo-24-crown-8 (2) has been described. Structure of (1) consists of the ion-pair complex with the Na atom coordinated to the six O atoms of the dibenzo-18-crown-6 ring and also to the water molecule in the apical position. The H atoms of the water molecule could not be located accurately but there are short contacts with the O atoms from the second uncomplexed crown molecule which indicate the hydrogen bonding. In (2) the Na ion is completely encapsulated by the crown molecule and coordinated to the eight oxygen atoms forming nesting complex.

In the present work, a novel microextraction method named in situ solvent formation microextraction (ISFME) using ionic liquids (ILs) for preconcentration of carbaryl and carbofuran in water samples is introduced. In this method, a small amount of sodium hexafluorophosphate (NaPF6), as an ion pairing agent, was added to a sample solution containing a small quantity of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4] as a hydrophobic ionic liquid. A cloudy solution formed as a result of formation of fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6]. After centrifugation, the fine droplets of the extractant phase settled to the bottom of the conical-bottom glass centrifuge tube. Analysis was carried out using HPLC-UV. To obtain the best extraction results, some experimental parameters affecting the extraction efficiency were optimized. Under optimum conditions, the calibration curve was linear in the concentration range of 0.05–50 ng mL−1 for two pesticides, with the square correlation coefficients (r2) equal to 0.998 for carbaryl and 0.997 for carbofuran. Good enrichment factors of 85 and 100 were achieved for carbaryl and carbofuran, respectively. The limits of detection (LODs) (S/N = 3) were 0.09 ng mL−1 and 0.1 ng mL−1 for carbaryl and carbofuran, respectively. The method was successfully applied to analysis of pesticide residues in water samples.

The structure of sodium hexafluorophosphate monohydrate, NaPF(6) x H(2)O, has been inadvertently redetermined, revealing that the previously reported space group, Imma, was assigned incorrectly, with the a and b axes interchanged. The correct space group is Pnna. The program PLATON [Spek (2003). J. Appl. Cryst. 36, 7-13] suggested both Imma and Pmma as possible space groups, but only Pnna is consistent with the systematic absences. The inter-ionic and hydrogen-bonding interactions in the lattice form a three-dimensional network.

The redox switching of poly(vinylferrocene) (PVF) films was investigated using the electrochemical quartz crystal microbalance in conjunction with cyclic voltammetry (at different voltage scan rates) and reverse potential steps. The mechanism of the redox process was determined using PVF films supported on Au electrodes and exposed to aqueous bathing solutions of 0.1 M sodium hexafluorophosphate. PVF electro-oxidation proceeds via coupled oxidation of uncharged ferrocene sites and entry of counterion and is followed by the entry of water into the film. Structural changes within the polymer may also accompany the latter two steps. Any of these three steps may be the slowest for particular redox conditions. The controlling kinetic step depends on the film's instantaneous water content, its instantaneous oxidation state, the electrochemical control function, the direction of redox switching, and the associated time scale of the experiment. We describe a new general quantitative approach based upon comparison of the instantaneous fluxes of solvent (water) and counterion during the redox cycle to characterize the rate-controlling process as a function of the extent of film oxidation. This new methodology has the capability to resolve time scale- and potential- (charge-) dependent mechanistic shifts and film relaxation phenomena as they are reflected through the ratio of fluxes of solvent and counterions.

Formal potentials and diffusion coefficients of the alkali metal couples of lithium, sodium, and potassium hexafluorophosphate salts dissolved in 1-butyl-3-methylimidazolium hexafluorophosphate were determined using a hanging mercury drop electrode as the working electrode. Chronoamperometry was used to determine the diffusion coefficients, which ranged from 1.4 X 10 -8 to 4.5 × 10 -8 cm 2 /s for the Na and K cations, respectively. Formal reduction potentials of -2.96 ± 0.01 V and -3.35 ± 0.01 V vs. the ferrocene/ferrocenium couple were obtained for sodium and potassium using normal pulse voltammetry. The presence of adsorption maxima in the lithium normal pulse voltammograms necessitated the use of chronopotentiometry to determine a lithium formal potential of -2.45 ± 0.02 V.

The i.r. and Raman spectra of NaPF6·H2O and partially deuterated NaPF6·H2O have been obtained. All of the fundamental modes of the PF−6-ion have been located and the rule of mutual exclusion applies for these modes. In the Raman spectra, the number of components observed for each fundamental PF−6-mode is consistent with the number of site group components predicted. The hydrogen bonds in NaPF6·H2O are very weak and the hydrogen bond energy is of the order of 1.7 kcal/mole. The frequencies of the nine fundamental modes of the H2O, D2O and HDO molecules have been converted to harmonic values. It is shown that if the HOH valence angle is varied, and the effective harmonic force field of the water molecules calculated for each assumed value, an estimated value of this angle in NaPF6·H2O can be obtained. The librational modes of the water molecules have been located and are assigned to rocking and wagging modes.

Fluorine-19 and sodium-23 NMR measurements were carried out on sodium hexafluorophosphate solutions in a number of solvents. In solvents of medium polarity and donicity (e.g., propylene carbonate, acetone, acetonitrile) the19F chemical shift moved upfield with increasing concentration of the salt. This behavior is indicative of anion-cation interactions which may be of long-range type, i.e., formation of solvent-separated ion pairs; the possibility of contact ion pair formation, however, cannot be excluded. In solvents of low polarity and donicity (acetic acid, tetrahydrofuran), the salt is essentially completely associated in the 0.1–1.0M concentration range. On the other hand, in solvating solvents with high dielectric constants, such as dimethyl-formamide, dimethylsulfoxide, and formamide, there is very little ionic association in the same concentration range. The above conclusions are supported by23Na chemical shift measurements. Potassium hexafluorophosphate solutions do not show any concentration dependence of the19F chemical shifts, while for tetra-n-butylammonium solutions the19F resonance moves downfield with increasing concentration of the salt.

The crystal structure of 2NaPF6·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P21/n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) A, and β = 108.98(1)°. The two NaPF6 units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner.

The OH and OD stretching modes in partially deuterated NaPF 6 ·H 2 O occur at what seem to be the highest frequencies so far recorded for HDO groups in crystalline hydrates, showing that the hydrogen bonds in this compound are very weak.

The spin‐lattice relaxation times of fluorine, phosphorus, protons, and deuterons in solutions of sodium hexafluorophosphate and sodium monofluorophosphate in water and deuterium oxide have been measured at 25 MHz by pulsed techniques over the temperature range 250–363°K. The fluorine and phosphorus spin‐lattice relaxation times in both salt solutions have been found to be the sum of interactions due to spin‐rotation and dipole‐dipole contributions. The spin‐rotation constants for fluorine and phosphorus in PF6− are 3.56 and 3.86 kHz, respectively. The spin‐rotation constants for fluorine and phosphorus in PO3F2− are 23.6 and 21.4 kHz. Spin‐rotation constants were also calculated from chemical shielding data. The results for the nearly spherical PF6− anion are in accord with rotation diffusion theory. The 31P relaxation data seem to indicate that the PF6− anion follows the J‐diffusion model of McClung whereas the 19F relaxation data indicate that the M‐diffusion model is followed. The reorientation correl...

Trimethyl phosphite reacts with (((C/sub 6/Me/sub 6/)RuCl/sub 2/)/sub 2/) in methanol to yield the cation ((C/sub 6/Me/sub 6/)RuCl(P(OCH/sub 3/)/sub 3/)/sub 2/)/sup +/, which has been isolated as a chloride or hexafluorophosphate salt. This cation undergoes a sequence of two Michaelis-Arbuzov type reactions to give the neutral complex and the L/sup -/ anion ((C/sub 6/Me/sub 6/)RuCl(P(O)(OCH/sub 3/)/sub 2/)/sub 2/)/sup -/. Attempts to isolate the anion in the form of its sodium salt NaL have led to products that always contain additional sodium iodide or sodium hexafluorophosphate. The free acid HL can be prepared by protonation from NaL or directly from the reaction of (((C/sub 6/Me/sub 6/)RuCl/sub 2/)/sub 2/) with dimethyl phosphonate, HP(O)(OCH/sub 3/)/sub 2/. L/sup -/ is a uninegative, potentially bidentate or tridentate ligand with an O,O,Cl donor set. It reacts with many transition-metal and main-group-metal ions, e.g. M/sup n+/ = Mg/sup 2 +/, Mn/sup 2 +/, Co/sup 2 +/, Ni/sup 2 +/, Cu/sup 2 +/, Zn/sup 2 +/, Cd/sup 2 +/, Pb/sup 2 +/, Al/sup 3 +/, or Fe/sup 3 +/, to give 2:1 complexes of the composition (ML/sub 2/)/sup (n-2)+/. The reactions of the complexes (((ring)MCl/sub 2/)/sub 2/), (ring)M = (C/sub 5/Me/sub 5/)Rh, (C/sub 6/Me/sub 6/)Ru, and (p-cymene)Ru, withmore » L/sup -/ lead to the cationic complexes ((C/sub 5/Me/sub 5/)RhL)/sup +/, ((C/sub 6/Me/sub 6/)RuL)/sup +/, and ((p-cymene)RuL)/sup +/, which have been isolated as hexafluorophosphate salts. HL oxidatively adds to the metal(0) complexes (Mo(CH/sub 3/CN)/sub 3/(CO)/sub 3/) and (W(DMF)/sub 3/(CO)/sub 3/) to yield metal hydride complexes of the composition (LM(CO)/sub 3/H). The molybdenum hydride is labile and rapidly gives HL and Mo(CO)/sub 6/ under an atmosphere of CO gas.« less

The reaction of 1-n-butyl-3-methylimidazolium chloride (BMI.Cl) with sodium tetrafluoroborate or sodium hexafluorophosphate affords the molten salts BMI.X ( 1 , X= BF 4 and 2 , X= PF 6 ). Compounds 1 and 2 are viscous liquids within a wide range of temperature (down to 192 K). IR, NMR, density, viscosity and conductivity measurements suggest that compound 2 behaves quasi-molecular. Compound 1 is quasi-molecular below 279 K, but at higher temperatures is probably composed of imidazolium and tetrafluoroborate ions in an extended hydrogen-bonded network.

Etude de la reduction electrochimique de sels de tetrabutylammonium sur une electrode de platine recouverte de mercure. Formation de l'amalgame de tetrabutylammonium(I). Par reaction de (I) avec des sels de sodium, obtention des sels de tetrabutyl ammonium correspondants

The first electron transfer in an organometallic reaction induced by the addition of a salt to a solution is reported.