Tetraphenylborate Anion Research Articles

ChemInform Abstract: Metal‐Free Carbon—Carbon Cross‐Couplings Between the Ion Pairs in Sulfonium Tetraphenylborates.

Abstract A series of sulfonium tetraphenylborates can be readily prepared by the metathesis of sulfonium halides with sodium tetraphenylborates. After heating at 120–150 °C, the sulfonium tetraphenylborates can smoothly undergo the cross-couplings between the tetraphenylborate anions and the sulfonium cations in the absence of a metal catalyst. For carbonylmethyl-, benzyl-, and allylsulfoniums, the corresponding carbonylmethyl–phenyl, benzyl–phenyl, and allyl–phenyl cross-coupling products can be obtained in 22–76% yields. An interionic electron-transfer mechanism for this cross-coupling reaction is proposed.

Extraction of Lithium Using TBP and the Noncoordinating Cation Exchanger Tetraphenylborate: Principles of Selectivity from Sodium and Higher-Valent Cations

Extraction of lithium, calcium, and some other metal cations using tetraphenylborate/tributyl phosphate mixtures has been studied. The possibility of a qualitative change in the cation exchange extraction series towards the preferential recovery of lowly-charged (singly-charged) metal cations was shown for these systems. A change in the separation factors for singly- over multiply-charged cations in this system, compared to the known commercially available extractants such as alkylphosphoric, carboxylic, and other organic acids, is several orders of magnitude and increases when passing from doubly- to triply-charged metal cations, reaching, for example, values of 103 and more for the lithium/yttrium couple. It was assumed that the change in the extraction series was caused by the instability of the salts of the multiply-charged metal cations compared to that for the singly-charged cations due to the ionic character of the bond with the extracted metals and structural problems caused by the large volume of the tetraphenylborate anion. The investigated system can serve as a model for the development of a new class of extractants having a higher selectivity for singly-charged metal cations, in particular, for lithium.

Crystal structure of tri-phenyl(vinyl)-phospho-nium tetra-phenyl-borate.

The title ionic salt, C21H20P+·C24H20B−, crystallized with two independent vinyl­tri­phenyl­phospho­nium cations and two independent tetra­phenyl­borate anions per asymmetric unit. These four independent moieties contain nearly perfect tetra­hedral symmetry about their respective central C atoms. In the crystal, there are no π-stacking or other inter­molecular inter­actions present.

Metal-free carbon–carbon cross-couplings between the ion pairs in sulfonium tetraphenylborates

A series of sulfonium tetraphenylborates can be readily prepared by the metathesis of sulfonium halides with sodium tetraphenylborates. After heating at 120–150°C, the sulfonium tetraphenylborates can smoothly undergo the cross-couplings between the tetraphenylborate anions and the sulfonium cations in the absence of a metal catalyst. For carbonylmethyl-, benzyl-, and allylsulfoniums, the corresponding carbonylmethyl–phenyl, benzyl–phenyl, and allyl–phenyl cross-coupling products can be obtained in 22–76% yields. An interionic electron-transfer mechanism for this cross-coupling reaction is proposed.

(But-oxy-methyl-idene)di-methyl-aza-nium tetra-phenyl-borate aceto-nitrile monosolvate.

In the title solvated salt, C7H16NO+·C24H20B−·C2H3N, the C—N bond lengths in the cation are 1.2831 (19), 1.467 (2) and 1.465 (2) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2950 (18) Å shows a double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. The two C atoms of the n-butyl group are disordered over the two sites, with refined occupancy ratios of 0.890 (5):0.110 (5) and 0.888 (4):0.112 (4). In the crystal, C—H⋯π inter­actions occur between the methine H atom, H atoms of the –N(CH3)2 and –CH2 groups of the cation, and two of the phenyl rings of the tetra­phenyl­borate anion. The latter inter­action forms an aromatic pocket in which the cation is embedded. Thus, a two-dimensional pattern is created in the ac plane.

Analytical Methods for the Detection and Purification of ε-Poly-L-lysine for Studying Biopolymer Synthetases, and Bioelectroanalysis Methods for Its Functional Evaluation

This article describes new analytical methods for studying biopolymer ε-poly-L-lysine (εPL). The produced amount of εPL in culture broth can be determined based on the precipitation of polycationic εPL with a colored heteropolymolybdate anion and the color change of the supernatant. The product can be separated and purified by precipitation with the tetraphenylborate anion and reprecipitation in the form of the hydrochloride salt. These methods have been applied advantageously to the screening of εPL-synthetase. Also, pyrophosphate can be determined colorimetrically based on the formation of 18-molybdopyrophosphate species. The pyrophosphate determination has been successfully applied to the assay of adenylation enzyme, which plays important roles in the biosynthetic mechanism. Under certain conditions, εPL associates with a redox enzyme, glucose oxidase. The effect of the adduction on the stability and reaction rate of the enzyme can be evaluated by measuring the bioelectrocatalytic current, which is related to the enzyme activity. Electrochemical studies showed new applications of εPL as an enzyme stabilizer and a reaction enhancer.

English

A simple, precise and low cost conductometric method for the determination of alfuzosin hydrochloride and fexofenadine hydrochloride in pure form and pharmaceutical formulations using sodium tetraphenylborate has been described. The method is based on the formation of ion association complex of cations coming from the cited drugs with tetraphenylborate anions and the conductance of the solution is measured as a function of the volume of titrant. Various experimental conditions were evaluated. The described procedures allowed the determination of the studied drugs in double distilled water in the range of 2.13 - 10.65 and 2.50 - 13.45 mg of alfuzosin hydrochloride and fexofenadine hydrochloride, respectively. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method is indicated by the excellent recovery 99.85-102.49 and 99.80-100.48% for alfuzosin hydrochloride and fexofenadine hydrochloride, respectively, and the precision is supported by the low relative standard deviation < 3.04%. The method was further applied successively to pharmaceutical formulations, the proposed method offering a high degree of accuracy and precision when compared to potentiometric pharmacopoeial methods.

Separation and Purification of ε-Poly-L-lysine from the Culture Broth Based on Precipitation with the Tetraphenylborate Anion

A biopolymer ε-poly-L-lysine (εPL) exists as a fully protonated form (εPLH(n+)) in solutions at pH < 4. Around pH 3.5, at which the tetraphenylborate (TPB(-)) anion is not decomposed immediately, the εPLH(n+) cation associates with the TPB(-) anion to form a precipitate of 1:n stoichiometry, εPLH(TPB)(n). By the addition of NaTPB to a culture broth containing εPL and NH(4)(+) and K(+) ions, not only the polycationic εPLH(n+) but also the monovalent cations would be precipitated with the TPB(-) anion. However, εPLH(TPB)(n) was purified by washing the mixed precipitate with acetone, in which NH(4)TPB and KTPB are soluble. By mixing the εPLH(TPB)(n) precipitate and a high-concentration HCl solution, the TPB(-) anion was decomposed immediately to hydrophobic molecules. By the addition of a much larger volume of acetone to the reaction mixture, the decomposition products dissolved in the solvent. Simultaneously, εPL was precipitated as the hydrochloride salt. Thus, εPL has been separated and purified from the culture broth. Also, the method has been successfully applied to the separation of oligomeric εPL species. The present chemical separation method is rapid, simple, and easy to carry out, and can be utilized in bioengineering studies of such basic peptides or polyamines.

Achieving organic nanoparticles with redox-active capabilities: synthesis of gold nanoparticles in water as a proof-of-principle

Herein, we present a unique approach to easily achieve redox-active nanosized organic particles in aqueous environment using a strategy based on ion association between large organic ions, namely tetraphenylborate anions and thiazole orange cations. The anionic tetraphenylborate associates tightly with the cationic redox-active thiazole orange producing a well-defined meta-stable organic nanoscale particle (73 ± 20 nm). These redox-active nanosized organic particles can act as seed sites for metal reductions and as a proof-of-concept, they were used to reduce gold(III) to gold nanoparticles in a neutral, aqueous environment at room temperature.

2,3,5-Triphenyl-2H-tetrazol-3-ium tetraphenylborate

In the title salt, C19H15N4 +·C24H20B−, the tetra­phenyl­borate anion is in a tetra­hedral geometry around the B atom [C—B—C angles of 107.10 (9)–111.79 (9)°]. In the cation, the tetra­zole ring makes dihedral angles of 3.04 (7), 51.75 (7) and 51.13 (7)° with the attached phenyl rings. In the crystal, C—H⋯π inter­actions link the cations and anions into ion pairs.

Solid-State Structures of Base-Free Lithium and Sodium Tetraphenylborates at Room and Low Temperature: Comparison with the Higher Homologues MB(C6H5)4 (M = K, Rb, Cs)

Lithium and sodium tetraphenylborate were subjected to an X-ray diffraction analysis to elucidate the solid-state structures at room (RT) and low temperature (LT). As in the potassium, rubidium, and cesium tetraphenylborates the lithium tetraphenylborate forms polymeric columns consisting of alternating Li+ and [B(C6H5)4]− ions. The lithium cations are coordinated by four η1-bonded phenyl rings of two tetraphenylborate anions. Each polymeric column is surrounded by six adjacent columns. The RT structure of sodium tetraphenylborate is almost identical with those of the heavier salts KB(C6H5)4, RbB(C6H5)4, and CsB(C6H5)4 (columns of alternating M+ and [B(C6H5)4]− ions; each column is surrounded by four adjacent columns). The LT structure of NaB(C6H5)4 is different and resembles the solid-state structure of the lithium salt. In addition, single-crystal structures of RbB(C6H5)4 (LT) and CsB(C6H5)4 (RT) have been determined for the first time at the temperature specified.

Stepwise acetylide ligand substitution for the assembly of ethynylbenzene-linked Co(III) complexes

We describe the preparation and structural characterization of a family of chloro-ethynylbenzene complexes containing [(cyclam)Co]3+ units: [(cyclam)CoCl(CCPh)]X (X=Cl (1a), BPh4 (1b)), [(cyclam)2Co2Cl2(p-DEB)]X2 (X=Cl (2a), BPh4 (2b)), [(cyclam)3Co3Cl3(1,3,5-TEB)]X3 (X=Cl (3a), BPh4 (3b)), [(cyclam)2Co2Cl2(1,3,5-TEBH)]X2 (X=Cl (4a), BPh4 (4b)), where the bridging ligands p-DEB and TEB are the bis- and tris-deprotonated anions of 1,4-diethynylbenzene and 1,3,5-triethynylbenzene, respectively. Cyclic voltammetry of [(cyclam)3Co3Cl3(1,3,5-TEB)]Cl3 (3a) suggests that electrochemical reduction of the Co(III) centers to Co(II) is accompanied by complex dissociation resulting from the increased lability of the Co(II) ions. Inclusion of the tetraphenylborate anions in 1b–4b allows for the possibility of stepwise acetylide substitution by imparting complex cation solubility in tetrahydrofuran: trans-[(cyclam)Co(CCPh)2](BPh4) (5) is prepared by mixing LiCCPh with 1b. Isolation of 5 demonstrates the feasibility of metallodendrimer synthesis using octahedral first-row transition metal nodes, which awaits demonstration.

Photocurrents from the Direct Irradiation of a Donor–Acceptor Complex Contained in a Thin Film on Indium Tin Oxide

We describe the performance of a photoelectrochemical cell based on an electron donor–acceptor (EDA) complex formed by the association of tetraphenylborate anion with a viologen dication siloxane film immobilized on an indium tin oxide (ITO) electrode. Visible irradiation of a weak absorbance band of the EDA complex leads to simultaneous photoreduction of the viologen and photooxidation of the tetraphenylborate, forming a viologen monocation radical and tetraphenylborate radical. Spontaneous decomposition of the latter to products incapable of further reaction inhibits reverse electron transfer, permitting harvesting of the redox equivalents stored as the viologen monocation radical at the electrode. Results of statistically designed two-level factorial experiments indicate that the photocurrent increases with light intensity (L) and viologen coverage (P), but decreases with viologen siloxane film age (A). Although the solution BPh4– concentration (F) does not significantly affect the photocurrent response under our experimental conditions, the nature of the electrolyte anion (C) does. Although significant interactions among the L, P, A, and C variables exist, our analyses provide a model that (1) describes the viologen film aging; (2) adequately predicts cell photocurrent responses as functions of levels of the L, P, and, to a somewhat lesser extent, A variables; and (3) identifies areas for improvement and optimization of cell performance.

Carbon Nanoparticle Surface Electrochemistry: High‐Density Covalent Immobilisation and Pore‐Reactivity of 9,10‐Anthraquinone

Abstract2‐Bromomethyl‐9,10‐anthraquinone is covalently bound to carbon nanoparticle surfaces (Emperor 2000, Cabot Corp., with sulphonamide groups, ca. 9 to 18 nm diameter) with a coverage of ca. 250 anthraquinone molecules per particle (ca. 180 Å2 per anthraquinone). The resulting hydrophobic carbon particles are dispersed in ethanol and coated onto glassy carbon electrodes. Electrochemical experiments are reported demonstrating the effect of surface coverage, scan rate, and pH. A linear shift in reversible potential of ca. 59 mV per pH unit from pH 2 to 12 is observed consistent with the reversible 2‐electron 2‐proton reduction of anthraquinone. High density of anthraquinone in carbon nanoparticle aggregates causes buffer capacity effects. Binding of hydrophobic tetraphenylborate anions into carbon nanoparticle aggregate pores is demonstrated. Applications in buffer characterisation and pH‐sensing are discussed.

Electrogenerated chemiluminescence in systems with tetraphenylborate anion as a co-reactant

The study of electrogenerated chemiluminescence (ECL) in aqueous and non-aqueous media with tetraphenylborate anion as a co-reactant is reported. The obtained results indicate that tetraphenylborate acts according to an oxidative reduction scheme and forms a strong reducer after being homogeneously oxidized by a radical cation or dication of luminophore. Spectral measurements prove that light emission originates from the luminophore present in solution and practically no emission occurs when only tetraphenylborate ion is oxidized at the electrode. Since the tetraphenylborate ion is a well known analytical reactant and precipitates a number of metal and organic cations its electrochemiluminescent detection can be used for their assay. It can also be applied as an efficient co-reactant for electrogenerated chemiluminescence excitation both in aqueous and non-aqueous media.

Ion-selective electrode for the determination of dimethylbenzylammonium ions

A sensor is proposed for the direct potentiometric determination of dimethylbenzylammonium in acid and neutral aqueous solutions. The sensor membrane is made of a polymeric composition on the basis of polyvinylchloride containing an ion associate and a solvent as a plasticizer. Salts of the tetraphenylborate anion and its derivatives served as ionophores. Basic electroanalytical parameters of the developed potentiometric sensors are studied and the pH range of their possible application is determined. The developed sensor is used as a reference electrode in the potentiometric titration of dimethylbenzylammonium with tetraphenylborate anions.

A Low-Cost Portable Microcontrolled Nephelometer for Potassium Determination

A low-cost portable microcontrolled nephelometer for the determination of potassium in coconut water and energy beverages is proposed. The nephelometer was constructed using two LEDs (light emitting diodes) as radiation sources at 465 nm and 880 nm, two photodiodes as photodetectors, and a peripheral interface controller (PIC) to acquisition and processing data of the nephelometer. The nephelometer was used to determine potassium ions by monitoring the precipitate formed from the reaction between K+ and tetraphenylborate anion in a basic medium in the presence of polyvinyl alcohol. The analytical curve was linear in the potassium concentration range from 5.0×10"6 to 5.0×10"4 mol L"1, with a limit of detection of 4.0×10"7 mol L"1. A relative standard deviation of 0.2 % for 1.6 × 10"4 mol L"1 potassium solution (n = 10) was obtained. Fast and reliable responses, low power consumption are other attractive features of the proposed nephelometer.

CRYSTAL STRUCTURE OF [Bis(DIMETHYLFORMAMIDE) Bis(2,2’-PYRIDYL)QUINOLINE)IRON(II)]Bis-(TETRAPHENYLBORATE)

The goal of this research is to obtain single crystal and structural information of iron(II) complex with 2,(2’pyridyl)quinoline(pq) ligands. The reaction of iron(II) salt with 2,(2’-pyridyl)quinoline ligand and sodium tetraphenylborate in the molar ratio of 1:3:2 in methanol-N,N-dimethylformamide(dmf) solution results in an iron(II) complex. The formula of the [Fe(pq)2(dmf)2](BPh4)2 complex has been obtained from the iron(II) and C, H, N contents. Single crystal of [Fe(pq)2(dmf)2](BPh4)2 suitable for X-ray investigation was obtained by evaporation of the complex solution in N,N-dimethylformamide at room temperature after 24 hours. This compound crystallizes in monoclinic system with C2/c space group, a = 27.950(4), b = 14.169(7), c = 17.717(9) A and β = 105.669(11)°. The structure consist of iron(II) is chelated by two pq ligands through the N atoms and two dmf molecules in a six-coordination environment. The charge of the [Fe(pq)2(dmf)2] cation is balanced by two tetraphenylborate (BPh4) anions.

ChemInform Abstract: Palladium-Catalyzed Phenylation of Allylic Acetates by Tetraphenylborate Anion.

Abstract Commercial sodium tetraphenylborate is a convenient phenylating reagent in the palladium(0)-catalyzed substitution of allylic acetates. Two phenyl groups of NaBPh 4 are available for transfer. Triphenylboron is also a phenylating agent in this reaction.

Synthesis, Structure, and Density Functional Theory Analysis of a Scandium Dinitrogen Complex, [(C5Me4H)2Sc]2(μ-η2:η2-N2)

Investigation of the bis(tetramethylcyclopentadienyl) metallocene chemistry of scandium has revealed that the method involving reduction of trivalent salts with alkali metals used with lanthanides can also be applied to scandium to make a dinitrogen complex of the first member of the transition metal series. ScCl(3) reacts with 2 equiv of KC(5)Me(4)H to form (C(5)Me(4)H)(2)ScCl(THF), 1, which reacts with allylmagnesium chloride to make (C(5)Me(4)H)(2)Sc(eta(3)-C(3)H(5)), 2. Complex 2 reacts with [HNEt(3)][BPh(4)] to yield [(C(5)Me(4)H)(2)Sc][(mu-Ph)BPh(3)], 3, which has just one primary Sc-C(phenyl) contact connecting the tetraphenylborate anion and the metallocene cation. Treatment of 3 with KC(8) in THF under N(2) generates [(C(5)Me(4)H)(2)Sc](2)(mu-eta(2):eta(2)-N(2)), which has a coplanar arrangement of scandium and nitrogen atoms within a square planar array of tetramethylcyclopentadienyl rings. Density functional calculations explain the bonding that results in the 1.239(3) A N-N bond distance in the (N=N)(2-) moiety.