Addition Of KPF6 Research Articles

Determination of four pyrethroid insecticides in water samples through membrane emulsification-assisted liquid–liquid microextraction based on solidification of floating organic droplets

A novel membrane emulsification-assisted liquid–liquid microextraction method based on the solidification of floating organic drops was used to detect four pyrethroid pesticides (deltamethrin, etofenprox, fenpropathrin, and bifenthrin). In this method, [P44412]Br was used as a surfactant that could be removed from water via the addition of KPF6. The extraction solvent was separated after centrifugation and solidification on the water surface. The parameters affecting the recovery of the target compounds, including the surfactant amount, [P44412]Br-to-KPF6 molar ratio, addition of salt, extraction solvent volume, and temperature, were individually optimized and further analyzed through an orthogonal array design (OAD) experiment. The optimized conditions were based on the results of the OAD experiment and single-factor analysis. Using these experimental conditions, the recovery of the four pyrethroids ranged from 91.3% to 98.1% with relative standard deviation (RSD) values ranging from 1.7 to 2.2%. Good linearity was observed, with values from 0.9982 to 0.9997, and the linear range was between 1 and 500μg/L (5–500μg/L for fenpropathrin). The limit of detection (LOD) values based on a signal-to-noise ratio (S/N) of 3:1 were 0.37–0.75μg/L. The enrichment factor ranged from 90 to 96. Therefore, this method is suitable for the determination of pyrethroid pesticides in environmental water samples.

2.2]Paracyclophanes with N-Heterocycles as Ligands for Mono- and Dinuclear Ruthenium(II) Complexes.

[2.2]Paracyclophane, with its unique structure, allows the design of unusual 3D structures by functionalization of this rigid and stable hydrocarbon scaffold. Therefore different mono- and homodisubstituted [2.2]paracyclophanes with pyridyl, pyrimidyl and oxazolinyl substituents were developed in order to evaluate their ability as bridging ligands for two ruthenium centres. With the successfully synthesized [2.2]paracyclophane-based N-donor functions, the cycloruthenation reaction using [RuCl2 (p-cymene)]2 as precursor was explored. Compared to 2-phenylpyridine, the [2.2]paracyclophane derivative is clearly inferior in the cycloruthenation reaction, resulting in poor yields for the neutral complexes. By addition of KPF6 , the cationic complexes can be obtained in good yields and are formed diastereoselectively in case of a pyridyl substituent, resulting in only one diastereomer for dinuclear ruthenium complexes of bispyridyl-substituted [2.2]paracyclophanes as bridging ligands.

Effects of KPF6 on the electrochemical performance of natural graphite/Li

Lithium hexafluorophosphate (LiPF6) is the best electrolyte for lithium-ion batteries because of its excellent performance. The conversion of KPF6 into LiPF6 is a green chemical process. However, KPF6 residues are introduced into the electrolyte during the preparation process. In this study, we evaluated the effects of KPF6 on the electrochemical performance of natural graphite/Li. The results of a cycling test showed that as the KPF6 content increased in the electrolyte, the specific capacity of the graphite electrode also increased gradually. The impedance of a solid electrolyte interphase (SEI) film was decreased by the addition of KPF6. Cyclic voltammograms showed that the addition of KPF6 had no effects on the insertion and extraction reactions of lithium ions on the graphite electrode. Analyses of the graphite electrodes using scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the addition of 0.09 and 0.2 wt% KPF6 did not change the main components of the SEI film, but the ROCO2Li content decreased and the Li2CO3 content increased. Therefore, the electrochemical performance of the graphite electrode was improved by lithium-ion migration on the SEI film, which protected the graphite layer.

Dinuclear iridium complexes with unsupported Ir–Cl–Ir bridges

Two unusual dinuclear iridium complexes are reported with unsupported bridging chloride ligands. The first comes from an aqueous solution of H2ClIr(PMe3)3 by the addition of KPF6.▪The second is formed in the reaction between H(C6H5)ClIr(PMe3)3 and TlPF6 in dichloromethane.▪Single crystal X-ray structures are provided for both μ-chlorodiiridium complexes.

Cationic tris(pyrazolyl)borate bipyrimidine complexes

The cationic complexes, [TpRNi(bpym)]+ {TpR = tris(3,5-diphenylpyrazolyl)borate, R = Ph21; tris(3-phenyl-5-methylpyrazolyl)borate, R = Ph,Me 2} were synthesized by reacting [TpRNiBr] (R = Ph2; Ph,Me) with bipyrimidine followed by subsequent addition of KPF6 in CH2Cl2. The green solids have been characterized by IR, UV–Vis and 1H NMR spectroscopy. Crystallographic studies of [TpPh,MeNi(bpym)]PF6 reveal a five-coordinate square pyramidal nickel centre with a κ3-coordinated TpPh,Me ligand and a chelating bipyrimidine ligand. Cyclic voltammetric studies show irreversible reduction with the degree of reversibility dependent on the type of TpR ligand.

Diffusion and NOE NMR studies on the interactions of neutral amino-acidate arene ruthenium(II) supramolecular aggregates with ions and ion pairs

The interaction between [RuCl(AA)(cymene)]n supramolecular aggregates (1, AA = alpha-amino-acidate = alpha-aminoisobutyrate; 2, AA = N,N-dimethyl-Gly; 3, AA = Ala; 4, AA = Pro; cymene = 4-isopropyltoluene) and ionic species derived from NBu4PF6 and KPF6 is investigated through diffusion NMR measurements and 19F,1H-hetero-nuclear Overhauser effect spectroscopy experiments in CDCl3 and CD2Cl2. Aggregates containing the -NH2 functionality (1 and 3) interact strongly with NBu4PF6 as demonstrated by the observation of intense nuclear Overhauser effects between the fluorine atoms of PF6(-) and the protons of [RuCl(AA)(cymene)]n. Unexpectedly, diffusion NMR measurements indicate that the average size of the aggregates increases when a small amount of NBu4PF6 is added (Csalt/CRu < 0.1) in CD2Cl2. At higher concentration levels of NBu4PF6 or in CDCl3, NBu4PF6 exerts a destructive effect that reduces the average size of the aggregates. [RuCl(AA)(cymene)]n aggregates with NR-H (4) and NR2 (2) functionalities are little affected by the addition of NBu4PF6. KPF6 also interacts with [RuCl(AA)(cymene)]n aggregates as demonstrated by the fact that it becomes noticeably soluble in CDCl3 and CD2Cl2. Diffusion1H-NMR experiments show that the addition of KPF6 does not markedly alter the average size of [RuCl(AA)(cymene)]n supramolecular aggregates. Interestingly, the average size of PF6(-)-containing supramolecular aggregates is, in some cases, slightly higher than that of the ones that do not contain PF6(-). This was deduced by independent measurements of the hydrodynamic volume of the anion and of the ruthenium complexes by diffusion 19F- and 1H-NMR experiments, respectively.

Carben‐analoge Amidoosmium‐Komplexe mit OsN‐Doppelbindung: Synthese, Struktur und Reaktivität von [(Mes)Os(=NHR)(PiPr3)]PF6

Carbene‐Type Amidoosmium Complexes with an OsN Double Bond: Synthesis, Structure and Reactivity of [(Mes)Os(=NHR)(PiPr3)]PF6*The reaction of [(Mes)Os(PiPr3)Cl2] (1) (Mes1,3,5‐C6H3Me3) with primary amines RNH2 (RPh, Me, Et) in acetone/water (1:1) gives, after addition of KPF6, the amidoosmium(II) complexes [(Mes)Os(=NHR)(PiPr3)]PF6 (2–4) in 60–80% yield. From 1 and Et2NH, the chloro(hydrido)compound [(Mes)1‐OsH(PiPr3)Cl] (5) is formed. The X‐ray structural analysis of 2 reveals that the geometry around the osmium atom is trigonalplanar (with the midpoint of the mesitylene ring as one coordination site) and that the OsN distance of 1.923(4) Å is in agreement with an OsN double bond. Thermolysis of 4 (REt) at 165°C leads to the formation of the aldimino(hydrido)osmium complex [(Mes)OsH(NHCHMe)(PiPr3)]PF6 (6) by β1‐hydride migration from the NCH2 carbon atom to the metal atom. Protonation of 3 (RMe) with HCl gives the amine complex [(Mes)Os(NH2Me)(PiPr3)Cl]PF6 (7), whereas on treatment of 3 and 4 with CD3NO2 the deuterated derivatives [(Mes)Os(=NDR)(PiPr3)]PF6 ([D1]‐3, [D1]‐4) are almost quantitatively formed. Compound 2 (RPh) reacts with KOtBu by proton abstraction and phosphane elimination to give the dinuclear imidoosmium complex [(Mes)2Os2(μ1‐NPh)2] (8).

Reactions of cis-[PtCl2(PEt3)2] with silver salts in aqueous solution, in the presence or absence of PEt3

Reaction of AgX(X = NO3 or ½SO4) with cis-[PtCl2(PEt3)2] in neutral water affords [Pt2(OH)2(PEt3)4]2+ or [Pt(SO4)(PEt3)2] the latter of which can be isolated from dilute sulphuric acid solutions. In water in the presence of PEt3(2 mol equivalents), [Pt(PEt3)4][PtCl4] gives a mixture of [PtCl(PEt3)3]+ and [Pt(PEt3)4]2+ although the latter gives [PtCl(PEt3)3]+ and [PHEt3]+ on acidification. Addition of 2AgX (X = NO3, O2CMe, ClO4, or ½SO4) to these acidified solutions gives [PtX(PEt3)3]+, although, in aqueous solution, complex equilibria apparently exist between the co-ordinated anion and water. The ions [PtX(PEt3)3]+(X = NO3, ClO4, or O2CMe) can be isolated as their [PF6]– or [ClO4]–(X = ClO4) salts. For X =½SO4, attempts to isolate a product by addition of KPF6 generally led to [PtCl(PEt3)3]+ although on one occasion [Pt(H2O)(PEt3)3]2+ was recovered. Reaction of H2 with [PtY(PEt3)3]n+(Y = HSO4, n= 1; Y = H2O, n= 2) gives [PtH(PEt3)3]2+ which with K2S2O8 gives [PtY(PEt3)3]n+. The isolated complexes have been fully characterised by spectroscopic means and their relevance to systems employed in the photochemical decomposition of water is discussed.