Univalent Anion Research Articles

The effect of Cl − depletion and X − reconstitution on the oxygen-evolution rate, the yield of the multiline managanese EPR signal and EPR Signal II in the isolated Photosystem-II complex

The role of Cl − in photosynthetic O 2 evolution has been investigated by measurement of the steady-state O 2 rate and EPR of the electron donors responsible for the S 2 multiline signal and Signal II s upon Cl − depletion and substitution in Photosystem II membranes. Cl − removal has three effects upon the donor side of Photosystem II. (1) It abolishes O 2 evolution reversibly, while decreasing the yield of the S 2 multiline signal indicative of the manganese site of the O 2-evolving complex in the S 2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S 1 centers having reduced primary acceptor Q A to form S 0 centers having a reduced Signal II s species. Reactivation of O 2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl − > Br − ∼ NO 3 − ⪢ OH − ∼ F −. Reactivation of the S 2 multiline signal follows Cl − ∼ Br − > NO 3 − ∼ OH − > F −, in near correspondence with reactivation of O 2-evolution rates. Cl − titrations of F −-inhibited samples reveal two binding sites for Cl − which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S 1 → S 2 light reaction, while the lower-affinity site reactivates the S 3 → S 0 light reaction. The high-affinity site is located within the O 2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O 2-evolving complex. The results are compared with Cl −/F − exchange equilibria for Mn 3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.

Electrochemical Reduction of Some Tris(β-diketonato)ruthenium(III) Complexes in Acetonitrile and Interaction of the Reduced Anions with Lithium and Sodium Ions

Abstract In tetraethylammonium perchlorate–acetonitrile solution, [Ru(R1–CO–CR2–CO–R3)3] (R1,R3=–CH3, –CF3, –C6H5, –C(CH3)3; R2=–H, –C6H5) was reversibly reduced at a dropping mercury electrode to the corresponding univalent anion. A linear relationship was found between the half-wave potential and the sum of the Hammett constants of the substituents of ligands. In some cases, the polarogram and the cyclic voltammogram were shifted to more positive potentials in the presence of lithium or sodium ions. This effect was explained quantitatively by the two-step association between the reduction product, [Ru(R1–CO–CR2–CO–R3)3]−, and alkali metal ions. The association constants were calculated. The K2 values were appreciable and the K1 values were much larger than expected for a simple electrostatic interaction. Furthermore, the K1 values were linearly related to the sum of the Hammett constants of the substituents of the ligands. These results suggest the importance of the local charge distribution on the complex anions. In the presence of lithium ion, [Ru(acac)3]− forms Li[Ru(acac)3] which is insoluble in acetonirile.

Cobalt(III) Complexes with N,N′-Ethylene-bis(salicylideneaminate) and a Related Quadridentate Ligand

Abstract Numerous six-coordinate cobalt(III) complexes with N,N′-ethylene-bis(salicylideneaminate) and N,N′-ethylene-bis [2-hydroxynaphthyl (1) -methyleneaminate], abbreviated as salen and nalen, respectively, have been synthesized and characterized. The complexes prepared are of the types [Co(salen)L2]X, MI [CoX2(salen)], [CoX(salen)H2O], [Co(nalen)L2] and [CoX(nalen)L], where X and L denote a univalent anion and a neutral unidentate li-gand, respectively. All these complexes are diamagne-tic and trans-six-coordinate.

ChemInform Abstract: A THEORETICAL STUDY OF THE ENERGIES OF SOLUTION, ASSOCIATION, AND MIGRATION FOR UNIVALENT SUBSTITUTIONAL ANION IMPURITIES IN ALKALI METAL CHLORIDE CRYSTALS

Theoretical calculations have been made of the energy change accompanying the substitution of a univalent anion, F−, Br−, or I−, into crystals of the alkali metal chlorides LiCl, NaCl, KCl, and RbC...

A theoretical study of the energies of solution, association, and migration for univalent substitutional anion impurities in alkali metal chloride crystals

Theoretical calculations have been made of the energy change accompanying the substitution of a univalent anion, F−, Br−, or I−, into crystals of the alkali metal chlorides LiCl, NaCl, KCl, and RbCl. Association energies for the formation of nearest neighbour (nn) or next nn complexes with a vacancy in the anion sub-lattice and the activation energies for the four basic kinds of single vacancy jumps have also been calculated. The results of these calculations are discussed with respect to ion size and polarization effects and their relation to the activation energy (E′) for the diffusion of a univalent impurity in the host crystals. The availability of experimental values of E′ for some systems permits an assessment of the contribution to E′ from the temperature dependence of the correlation factor and from vacancy pair diffusion.

Addition of alcohols to phenyldicyandiamides metal complexes of 1-phenylamidino-o-alkylurea and related ligands

Abstract Copper(II), nickel(II), cobalt(II) and palladium(II) promote addition of alcohols to phenyldicyandiamide, o-chloro- and p-chlorophenyldicyandiamide. 1-Phenylamidino-O-alkylurea (1-PhAAUH), 1-o-chlorophenylamidino-O-alkylurea (1-o-ClPhAAUH) and 1-p-chlorophenylamidino-O-alkylurea (1-p-ClPhAAUH) metal complexes are thereby formed. Copper(II) gives two series of complexes: (1) [Cu(1-PhAAUH)2]X2 (X = univalent anion). These complexes are red-violet (η = 18.8 kK), bi-univalent electrolytes and paramagnetic with a square planar [CuN4]chromophore. (2) Cu(1-PhAAUH)X2 (X = Cl, 1 2 SO 4 or NO3). These are blue to green and absorb about 15.2 kK for X = Cl, at 14.4 kK for X = 1 2 SO 4 and at 14.5 kK for X = NO3. The sulfato complexes are obtained only in methanol while the only nitrato complex has been obtained in ethanol medium. The sulfato complex is considered to contain a bridging sulphate group while the nitrate complex has both coordinated and ionic nitrate. Nickel(II) forms orange yellow coloured bis(ligand) complexes. They are diamagnetic, absorb around 22.7 kK and hence possess square planar[NiN4] geometry. Both copper(II) and nickel(II) bis(ligand) complexes show tetragonality in donor solvents. No bis(ligand) copper(II) and nickel(II) complexes were obtained with higher alcohols than ethanol. Palladium(II) reacts with the substituted dicyandiamides in different alcohols to provide dichloro-mono(ligand) complexes. They are diamagnetic and show the Pd-Cl stretch around 340 and 350 cm−1. Methanol addition reactions are also initiated by cobalt(II) ultimately giving tris(ligand) cobalt(III) complexes. With p-chlorophenyldicyandiamide a mixed chelate, p-chlorophenyldicyandiamide bis((1-p-chlorophenylamidino-O-methylurea) cobalt(III), is obtained. The compounds show the 1 A 1g → 1 T 1g transitions and are diamagnetic. Characterisation of the above complexes have been made on the basis of elemental analyses, alkoxyl determinations, conductance, electronic absorption spectra, magnetic moments and IR spectra. The free ligands are too unstable to be isolated in the solid crystalline state.

Indicator dyes as probes of electrostatic potential changes on macromolecular surfaces

An indicator dye attached to an electrostatically charged macromolecular surface generally has a pK value (pKb') different from that of uncombined dye (pKf'). The question if changes in (pKb' - pKf'), designated as increment incrementpK, records changes in the electrostatic potential at the binding site has been examined in spectrophotometric and binding experiments, using the interaction of Chlorophenol Red and Phenol Red with human serum albumin and cationic micelles as examples. (1) In serum albumin solutions increment incrementpK is decreased by a reduction of pH. The decrease is correlated with the increase in positive charges on the protein molecule, and the response is attenuated by high ionic strength in accordance with electrostatic theory. (2) Opposite changes in binding affinity to serum albumin and increment incrementpK as a function of pH are observed; the binding of basic (bivalent anion) dye is more susceptible to a change in pH than in the acidic (univalent anion) form. (3) Preferential uptake of the basic as compared to the acidic form of dye is observed by binding to cetyltrimethylammonium chloride and cetylpyridinium chloride micelles (mu equals 0.033, [Cl-] equals 0.033 M). An increase in the ionic strength is accompanied by a positive value of increment incrementpK. The results are consonant with the view that the observed increment incrementpK values reflect changes in the electrostatic potential at the binding site with consequently little, if any, effect on the intrinsic pK. The extension of the method to measure changes in the electrostatic potential at binding sites on cell membranes is briefly discussed.

Kinetic and equilibrium studies on iron(II) and iron(III) pentacyanoferrates

The results of a kinetic investigation of the reaction of [FeII(CN)5(py)]3–(py = pyridine) with CN– and HCN are reported, together with a linear free-energy treatment of data obtained for aquation reactions of species of the type [FeII(CN)5X](X = an uncharged or univalent anion). Equilibrium studies of [FeII(CN)5OH2]3– and [FeIII(CN)5OH2]2– with a number of substituents have confirmed the class (b) or ‘soft’ character of the iron centre in these complexes.

1-Allyl-2-tetrazoline-5-thione as a reagent in inorganic qualitative analysis. Micro detection of iodate, iodide, and bismuth(III).

The sodium salt of 1-allyl-2-tetrazoline-5-thione (NaATT-5) is proposed as a new reagent for the detection of IO3−, I−, and Bi(III) ions. An aqueous solution of NaATT-5 reduces IO3− in acid medium to free iodine (formed via iodide) which is detected by reaction with starch. S2O32− is the only interfering species. I− and NO2− interfere only when both are present together. NaATT-5 also reacts with bismuth to form a canary yellow precipitate of [BiL2]+ X− (where X=a univalent anion other than I−; L=ATT-5). When the yellow precipitate is treated with iodide, X− is replaced by I− to form a complex [BiL2]+I−, which is orange in colour. This reaction provides the basis for the detection of bismuth as well as of I−. In the test for bismuth, Cu(II), Fe(III), S2O32−, IO3−, IO4−, and large quantities of NO2− interfere. The last four anions also interfere in the test for iodide. A method for the preparation of NaATT-5 is also reported.

Anion exchange resin selectivity as a function of resin composition, revisited

Abstract It is found that the Cl3CO2−Cl− and ReO4−Cl− (and presumably the ClO4−Cl−) Dowex 1 anion-exchange resin systems show no change or only a moderate increase in K B Cl with increasing Cl− mole fraction. This is in contradiction to a previous study with Dowex 2 resin that showed a very marked decrease in K B Cl . Thus, these systems show the same behavior as other univalent anion exchange systems, and there is no need to invoke a special ion-pair cluster mechanism.

Hexakisamine-and benzonitrilepentakisamine-complexes of ruthenium(II). The ruthenium induced activation of amines to oxidation

The synthesis is reported of a range of complexes of the type Ru IIL 6X 2· nH 2O and Ru IIL 5(NCPh)X 2 where L represents a primary amine of the type R· CH 2. NH 2 and X a univalent anion. The infra-red spectra are discussed and it is noted that the spectral frequencies are sensitive both to amine and the anion X, however for the higher amines ν(CN) for benzonitrile is on average 20 cm − lower than in the corresponding ammine complexes. The hexakisamine-complexes react with dioxygen to give products containing materials (cyanide or nitrile) derived from the oxidation of the co-ordinated amine. The stoicheiometry of the reaction is established in the methylamine case.

Synthesis and characterisation of rhodium(III) complexes containing nitrogen heterocyclic ligands

The synthesis and characterisation of complexes of the type trans-[RhL4X2]Y (L = 3 or 4-substituted pyridine, 3,5-disubstituted pyridine, isoquinoline, pyrimidine, pyrazole, thiazole, X = Cl, Br and for L = py I; Y = univalent anion) are described. Using the same catalytic method, N-methylimidazole and ammonia give complexes of the type [RhL5X]2+(X = Cl or Br), whereas 5-chloro- and 5-nitro-N-methylimidazole give complexes of the type trans-[RhL5X2]2+. All the complexes of the type trans-[RhL4X2]+ and also [RhL5Cl]2+(L =N-methylimidazole) undergo catalytic substitutions, and the nature of the products is discussed.

The5T2–1A1crossover in some iron(II)–amidine complexes: magnetic properties and Mössbauer spectra

The preparations of the new amidine, N′-(2-pyridylmethyl)picolinamidine (ppa), and two methyl-substituted derivatives (Meppa and Me2ppa) are described and their bischelate complexes with iron- and nickel-(II). Physical properties characterise the metal compounds as the hydrated salts of six-co-ordinate complex ions in which the ligands are terdentate, [M(ligand)2]X2,nH2O (X = univalent anion). Magnetic and Mossbauer measurements show that the ppa complexes of iron(II) exist in a temperature-dependent high-spin ⇌ low-spin equilibrium in accordance with a prediction based on the ligand-field spectra of the nickel(II) complexes. The iron(II) complexes of the substituted ligands are fully high-spin over the temperature range investigated.Electronic and Mossbauer spectra suggest that in the complexes the ligands are stabilised in the tautomeric form which provides for chelate ring conjugation, and that the local symmetry about the metal ion is approximately D2d

Silver(III) biguanides

A series of quadricovalent cationic complexes of silver(III) with biguanide and with methylbiguanide having the composition [AgIIIL2]X3, where L is a bidentate ligand and X a univalent anion, has been prepared and characterised. In alkaline, neutral, and feebly acidic medium (pH > 5), the biguanide molecule possesses filled π-type delocalised orbitals. Some of the d electrons in the hypothetical AgI complex are forced to occupy higher-energy antibonding orbitals from which they can be removed by oxidation to give an AgIII complex. All the compounds were found to be diamagnetic, indicating dsp2 hybridisation.

Changes of total water and sucrose space accompanying induced ion uptake or phosphate swelling of rat liver mitochondria.

1. Total water exchangeable with tritiated water and sucrose space were measured in rat liver mitochondria during the uptake of K(+) induced by valinomycin and the release caused by nigericin. The K(+) content and the sucrose-inaccessible water rose and fell together. 2. Swelling resulting from phosphate addition in a medium of high K(+) concentration was associated mainly with increased sucrose-accessible water, which carried dissolved K(+). This change was reversed by addition of ATP. 3. The response of the sucrose-inaccessible space to changed osmolarity was qualitatively that expected if the mitochondrial K(+) is assumed to be present in this space with a univalent anion. 4. It is brought out that the light-scattering method fails to distinguish between changes in sucrose space and in sucrose-inaccessible space, which in the present experiments could be altered respectively by phosphate (in high K(+) solution) and by cation uptake induced by antibiotic.

A new application of atomic absorption spectrophotometry : Determination of phthalic acid by solvent extraction with neocuproine-copper(I) chelate

A new application of atomic absorption spectrophotometry is reported for the determination of phthalic acid. Phthalic acid is extracted as the ion-pair formed between bis(neocuproine)-copper(I) and the univalent anion of phthalic acid with MIBK; the copper concentration in the extract is then determined by atomic ab sorption in an air-acetylene flame at the 3247 Å copper line. Optimal conditions are described. The absorbance of the extract showed a linear relationship to the concentration of phthalic acid initially present in the aqueous solution over the range of 4·10 -6 to 4·10 -5 M. The effect of some analogous aromatic carboxylic acids on the phthalate extraction and the composition of the extracted species were also investigated.

Pople-like SCF—LCAO—MO Treatment of 77′,88′-Tetracyanoquinodimethan and Its Univalent Anion

Roothaan closed- and open-shell SCF—LCAO—MO calculations were carried out for 77′,88′-tetracyanoquinodimethan (TCNQ) and its univalent anion (TCNQ−), respectively. The dominant integrals were evaluated semiempirically in the manner of Pariser, Parr, McWeeny, and Peacock, including the approximation of total zero-differential overlap (TZDO). Singlet and triplet spectra for TCNQ0 and doublet and quartet spectra for TCNQ− were calculated by means of a configuration-interaction treatment involving singly excited states. Good correspondence was obtained with the experimental spectra. In addition, also in the TZDO approximation, we calculated the same spectra based on a semiempirical evaluation of the dominant integrals in the manner of Mataga, Nishimoto, Popkie, and Moffat. The two sets of theoretical spectra can be taken to correspond equally well with experiment. Charge density and spin density in TCNQ− based on an approximation to a projected UHF wavefunction following Amos and Snyder were obtained. Comparisons made with SCF, Hückel, and McLachlan spin-density values show the usual correspondence, and there is reasonable agreement with an experimental value of the spin density at the unsubstituted ring carbon. Bond lengths obtained from bond orders agree very well with the x-ray results of Fritchie and Arthur on Cs TCNQ, where they observed two species of TCNQ and assigned one as TCNQ0 and the other as TCNQ−.

Nitrogenous chelate complexes of transition metals—III: bis-chelate complexes of nickel (II) with 1,10-phenanthroline, 2,2′-bipyridyl and analogous ligands

The preparation and properties of an extensive series of bischelated nickel(II) compounds of the type Ni chelate 2X 2. n solvent (where chelate = 1,10-phenanthroline, 2,2-bipyridyl, 8-aminoquinoline, and Schiff base ligands derived from biacetyl, and X = a univalent anion) are described. Available evidence (visible and i.r. spectra, conductometric and magnetic measurements) points to a cis-octahedral structure of such compounds, in contrast to the copper(II) compounds of the same empirical formula, which have a five co-ordinate structure. Structural isomerism has been observed in the pairs [Ni bipy 2I 2], [Ni bipy 3][Ni bipy I 4], and [Ni bipy 2(NCS) 2], [Ni 2 bipy 4(NCS) 2](SCN) 2; and, while compounds of the type [Ni chelate 3][Ni X 4] (where X = Cl, Br, I) are readily prepared, the corresponding isothiocyanato compounds are unstable with respect to brown polymeric species with the same empirical molecular formula. Perchlorate co-ordination has been demonstrated for the compounds Ni chelate 2(ClO 4) 2, both in the solid state and in nitrobenzene solution.

A new application of atomic absorption spectrophotometry: determination of phthalic acid by solvent extraction with neocuproine-copper(I) chelate

Abstract A new application of atomic absorption spectrophotometry is reported for the determination of phthalic acid. Phthalic acid is extracted as the ion-pair formed between bis(neocuproine)-copper(I) and the univalent anion of phthalic acid with MIBK; the copper concentration in the extract is then determined by atomic ab sorption in an air-acetylene flame at the 3247 A copper line. Optimal conditions are described. The absorbance of the extract showed a linear relationship to the concentration of phthalic acid initially present in the aqueous solution over the range of 4·10 -6 to 4·10 -5 M . The effect of some analogous aromatic carboxylic acids on the phthalate extraction and the composition of the extracted species were also investigated.

EFFECT OF ELECTROLYTE ENVIRONMENT ON DIVALENT TARTRATE ION MOBILITY

The variation of the electrophoretic mobility, uT, of divalent tartrate ion with changing electrolyte environment has been studied. Mobilities were determined from boundary velocity measurements at 1.00 °C in the Tiselius electrophoresis apparatus. The solutions used, which were adjusted to pH 8.3–8.5, were principally either 0.04667 M C2T or 0.01 M C2T–0.11 M CA, where C+, T=, and A− are, respectively, a univalent cation, divalent tartrate ion, and a univalent anion. Relative viscosities, ηrcl, of a number of these solutions were also obtained. For a given anion environment, the variation of uT with changing cation is characterized by a minimum at sodium and a maximum at tetramethylammonium for a series of six alkali metal and tetraalkylammonium ions. For the alkali metal cations and for tetrapropylammonium ion, uT undergoes a distinct decrease when the solution is changed from 0.04667 M C2T to 0.01 M C2T–0.11 M CCl. For all solutions containing an anion A−, uT decreases with increasing hydrocarbon content of A− for a given cation. Possible ion association, obstruction, and ion–solvent interaction effects are considered.