Tetraphenylborate complexes

Moody and coworkers and Buschmarm and coworkers were leaders in constructing efficient surfactant sensors. ISEs containing PVC membranes with ortho-nitrophenyloctyl ether (p-NPOE) as a plasticizer were suitable for the determination of amphoteric (ZS) and catirmic (CS) surfactants. At pH < 1.5, the ZS reacts as a CS and can be titrated by a bulky counter ion such as tetraphenylborate. Complexation of the ethoxylated part of nonirmic surfactants with a bivalent cation such as Ba " allows potentiometric titratirMi with tetraphenyl borate. Jones et al. " report a detection limit of 1 x 10 mol for Antarox 880. 

Bis(l-methylimidazol-2-yl)methane and -ketone with the dimer [Rh(CO)2Cl]2 in the presence of sodium tetraphenylborate give the dicarbonyl complexes 68 (X CHj, CO L = CO) where the carbonyl ligands may easily be substituted by the triphenyl phosphine ligands to yield 68 (X = CH, CO L = PPh ) (99JOM(588)69). The bis(l-methylbenzimidazol-2-yl)methane analogs of 68 (X=CH2 L=C0, PPhj) can be prepared similarly. 

Discussion. Potassium may be precipitated with excess of sodium tetraphenyl-borate solution as potassium tetraphenylborate. The excess of reagent is determined by titration with mercury(II) nitrate solution. The indicator consists of a mixture of iron(III) nitrate and dilute sodium thiocyanate solution. The end-point is revealed by the decolorisation of the iron(III)-thiocyanate complex due to the formation of the colourless mercury(II) thiocyanate. The reaction between mercury( II) nitrate and sodium tetraphenylborate under the experimental conditions used is not quite stoichiometric hence it is necessary to determine the volume in mL of Hg(N03)2 solution equivalent to 1 mL of a NaB(C6H5)4 solution. Halides must be absent. 

However, the energy difference between N- and S-bonded thiocyanate is very small and is influenced by an interplay of several factors steric effects, solvent and the counter-ion in ionic complexes. To illustrate the last point, in complexes [Pd[Et2N(CH2)2NH(CH2)2NH2]NCS]+, the PFg salt is N-bonded, as it is in the unsolvated BPhg salt. However, though the acetone solvate of the tetraphenylborate is N-bonded, the methanol solvate is S-bonded [126],... 

In the Me2dtc complex, a unique, 15-line, epr spectrum was reported (69) that was peculiar only to the tetraphenylborate salt. This suggests a V-V interaction in the lattice. Electrochemical studies on these [CpjVLJ complexes (L = dithiocarboxylato ligand) shows two well defined, polarographic, reduction waves, and, for the process at most positive potential, the reversible formation of a V(III) species was postulated (72-74). 

Xia and co-workers synthesised a number of Pd-NHC complexes (33, 34, 36) for carbonylative Suzuki reactions (Fig. 9.6) [41], Various aryl iodides were carbonylatively coupled (P = 1 atm) with either phenylboronic acid or sodium tetraphenylborate. All the complexes were highly active, but 33 provided the best results with >76% selectivity for ketone in all the reactions. Xia followed this work with the double carbonylation of various aryl iodides with several secondary amines using the catalysts [CuX(Mes)] (37-X) and [Cu(IPr)X] (38-X) (X = I, Br, Cl) (3 MPa, 100°C, 10 h) (Scheme 9.7) [42],... 

Sladek, A., Hofreiter, S., Paul, M. and Schmidbaur, H. (1995) Sodium tetraphenylborate as a phenylating agent for gold(I) complexes. Journal... 

Especially sensitive and selective potassium and some other ion-selective electrodes employ special complexing agents in their membranes, termed ionophores (discussed in detail on page 445). These substances, which often have cyclic structures, bind alkali metal ions and some other cations in complexes with widely varying stability constants. The membrane of an ion-selective electrode contains the salt of the determined cation with a hydrophobic anion (usually tetraphenylborate) and excess ionophore, so that the cation is mostly bound in the complex in the membrane. It can readily be demonstrated that the membrane potential obeys Eq. (6.3.3). In the presence of interferents, the selectivity coefficient is given approximately by the ratio of the stability constants of the complexes of the two ions with the ionophore. For the determination of potassium ions in the presence of interfering sodium ions, where the ionophore is the cyclic depsipeptide, valinomycin, the selectivity coefficient is Na+ 10"4, so that this electrode can be used to determine potassium ions in the presence of a 104-fold excess of sodium ions. 

Pneumaticakis 151) has reported the synthesis of complexes of the type [Ln(Py0)4(N03)]2+ which could be precipitated either as nitrate from very concentrated solutions or as perchlorate and tetraphenylborate from dilute solutions. 

It is generally observed that complexes with a maximum number of neutral ligands are obtained when anions such as perchlorate, tetraphenylborate, and hexa-... 

Through the presence of aromatic or pseudoaromatic groups in the molecule (tetraphenylborate and related derivatives, the tetraphenyl-arsonium ion, cationic triphenylmethane dyes, complexes of o-phenanthroline with divalent nickel or ion, where the hydrophobicity is increased by further substitution by a hydrophobic group on the pseudoaromatic nucleus). 

Phosphorus, arsenic, and antimony donor ligands. A general synthesis has been reported for trialkyl phosphite complexes of noble metals, including [RuLeJ, [RuXLsl, and [RuHLs]+ [L = P(OMe)3 or P(OEt)3 X = Cl or Br]. The complexes were isolated as their tetraphenylborate salts from reaction of the phosphite with methanolic solutions of suitable labile olefin... 

BAs we have shown above, interpretation of weak interactions is difficult even in the case of the complex CH4 HX, where HX is a pronounced proton donor. It is obvious that interactions C-H- H-C are more questionable in this sense. Nevertheless, a number of intermolecular C-H- H-C contacts, which are smaller than 3 A, have been observed for example, in the crystal structures of the organoammonium tetraphenylborate system [40], Primarily, these H H contacts are observed between hydrogen atoms in the phenyl rings located in neighboring... 

The drug substance has been determined by direct potentiometric titration using chlorpromazine-sensitive electrodes [78. These consisted of an electroactive material in the membrane being either the chlorpromazine complex with either tetraphenylborate or dinonyinaphthalene sulfonate set in a PVC matrix. 2-nitrophenyl octyl ether was used as the plasticizer. 

Liu et al. have reported the development and applications of the commonly used local anaesthetic sensitive field-effect transistor(FET) [56]. The ion-pair complexes of procaine with silicotungstate, tetraphenylborate, or reineckate were prepared as electroactive materials for a drug sensor. These active materials were coated onto the platinum draw wire of a MOSFET to make a local anaesthetic-sensitive FET that... 

Shen et al. have reported studies on procaine-selective electrodes embodying PVC membranes [57]. Various ion-pair complexes (procaine derivatives with tetraphenylborate, dipicrylamine, tetraiodomecurate, and reineckate) were incorporated into platinized PVC membranes, and with dinonyl phthalate as the solvent mediator, formed procaine selective electrodes. The efficiency and performance of these were compared, and it was found that procaine picrylamine and procaine tetraphenylborate were the best electroactive materials. The procaine picrylamine electrode exhibited a Nemstian response over the range 10 pM to 0.1 M, and was used as the indicator electrode for the potentiometric determination of procaine. The method recovery was found to be 99.8%, with a standard deviation of 0.9%. 

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