Separation of Monovalent and Divalent Cations on a Pure Silica Gel Column with Dilute Oxalic Acid Containing 18-Crown-6 as Mobile Phase

Summary Pure silica gel (Pia Seed 5S-60-SIL) has been investigated as a cation-exchange stationary phase for ion chromatography of common monovalent and divalent cations (Li⁺, Na⁺, NH₄⁺, K⁺, Mg²⁺, and Ca²⁺) with conductimetric detection; dilute oxalic acid (0.05 mm oxalic acid, pH 4.1, to 1 mm oxalic acid, pH 3.0) was used as mobile phase. The Pia Seed 5S-60-SIL silica gel acted as a cation-exchange stationary phase for these cations when 0.2 mm oxalic acid at pH 3.6 was used as the mobile phase. Excellent simultaneous separation and highly sensitive indirect conductimetric detection of these cations were achieved in 20 min on a 150 mm × 4.6 mm i.d. Pia Seed 5S-60-SIL silica gel column with 0.2 mm oxalic acid containing 4 mm 18-crown-6 (1,4,7,10,13,16-hexaoxacycloctadecane), pH 3.7, as mobile phase (detection limits (signal-to-noise ratio, 3, injection volume, 20 L), were 0.15 m for Li⁺, 0.16 m for Na⁺, 0.21 m for NH₄⁺, 1.0 m for K⁺, 0.17 m for Mg²⁺, and 0.25 m for Ca²⁺). The proposed IC–CD method was successfully applied to the separation and detection of major cations (Na⁺, NH₄⁺, K⁺, Mg²⁺, and Ca²⁺) in rain and river water samples.     

Relation between stability constants of metal ion cryptates in two solvents and the transfer activity coefficients of the metal ions

The extrathermodynamic assumption of Lejaille and Bessière that _1,2 log K (LM ⁿ⁺ )=–G _tr (M ⁿ⁺ ) in which K is stability constant and L is cryptand 2.2.2, 2 _B 2 _B 2, 2.2.1, or 2.1.1 has been tested in dipolar aprotic solvents for M ⁿ⁺ being Li⁺, Na⁺, K⁺, Ag⁺, Tl⁺, and Ba²⁺. The relation has been found generally acceptable for the dipolar aprotic solvents propylene carbonate, acetonitrile, N,N-dimethylformamide and dimethylsulfoxide, provided the size of the ion is equal to or smaller than the cavity of the cryptand. The relation does not hold for the hydrogen bonded donating solvents, water, and methanol.     

Metal bioaccumulation by the freshwater algaScenedesmus quadricauda

Bioaccumulation of six metals (Cu²⁺, Cu⁺, Mo⁶⁺, Mn²⁺, V⁵⁺, Ni²⁺) and their combinations by algaScenedesmus quadricauda was determined by using radio nuclide X-ray fluorescence (RXFA). The metals were added into the cultivation medium in concentrations corresponding with EC₅₀ value for each metal. The obtained results indicate that Ni²⁺, Cu²⁺ and Cu⁺ were accumulated in high amounts (20%, 17.5% and 15.19%) the Mo⁶⁺ ion (<0.2%) was accumulated in the lowest amount. For metal-metal interactions in accumulation of metal ions by algaS. quadricauda three types of answers were determined: inhibition (MoCu²⁺, Ni, Mn, V; VNi, Mn; MnNi, Cu²⁺, Cu⁺; Cu⁺Ni; Cu²⁺Ni; NiMn, V), enhancement (VCu⁺; Cu²⁺Mn;Cu⁺V, Mn; MnV; NiCu²⁺, Cu⁺) and neutral effect (VMo; Cu²⁺Mo; Cu⁺Mo; MuMo; NiMo).     

Synthesis and binding studies ofN-(2-Hydroxy-l-phenoxyacetyl) glycylglycine

The synthesis ofN-(2-hydroxy-l-phenoxyacetyl)glycylglycine3 from 2-acetoxyphenoxyacetic acid is described. Compound3, a simple model for the carboxy-containing ionophore, Lasalocid, binds cations in methanol in the order: Ca²⁺ Ba²⁺ > Sr²⁺ 2>> Li⁺ > Na⁺, K⁺.     

Complexation properties of phosphonocarboxylic acids in aqueous solutions

The concentration formation constants of phosphonoacetic acid (PAA) complexes with the Ca²⁺ and Mg²⁺ ions were determined in aqueous solution at 25°C by potentiometric and coulometric titrations at different ionic strengths and were extrapolated to I=0 in order to obtain thermodynamic values of the formation constants. Complexes were formed by the completely deprotonated K _f (ML) and monoprotonated K _f (MHL) forms of the PAA anion. The respective values for the complexes are: log K _f (CaL)=4.68±0.03, log K _f (CaHL)=2.61±0.08; log K _f (MgL)=5.58±0.09, log K _f (MgHL)=3.0±0.3. The enthalpy and entropy of complexation for the deprotonated Ca²⁺ and Mg²⁺ PAA species, determined from the temperature dependence of the log K _f (ML), are: H⁰(Ca) =0.6±0.2 kcal-mol^–1, S⁰(Ca)=21.4±0.6 cal-mol^–1-K^–1, H⁰(Mg)=3.0±0.7 kcal-mol^–1, and S⁰(Mg)=35±2 cal-mol^–1-K^–1. It is seen there-fore, that the complexes are entropy stabilized but enthalpy destabilized. Formation constants were also determined for Ca²⁺ and Mg²⁺ complexes with PAA analogs, phosphonoformic and 3-phosphonopropionic acids and the complexation of PAA was also studied at a single ionic strength, with Na⁺, Ag⁺, Tl⁺, Sr²⁺, Ba²⁺, Cd²⁺, Cu²⁺, and Pb²⁺ ions.     

Der Nachweis des Bleis durch selektive Papierchromatographie

Zusammenfassung Eine mit dem Pinsel auf das Papier aufgetragene CdS-Zone fällt die Ionen Hg²⁺, Hg⁺, Ag⁺, Cu²⁺, Bi³⁺, jedoch nicht Pb²⁺. Das Blei wird nach Durchwandern der Zone mit Ammoniumsulfid nachgewiesen. Es können 20 g Blei neben 20 mg Hg²⁺, 3 mg Cu²⁺, 15 mg Ag⁺ und 0,6 mg Bi³⁺ erkannt werden, wenn man die Chromatographie im Reagensglas durchführt.Herrn Professor Dr. Glemser danke ich für die Unterstützung der Arbeit durch Institutsmittel.     

Ion-transfer polarographic study of the distribution of alkali and alkaline-earth metal complexes with 3m-crown-m ether derivatives (m = 6, 8) between water and nitrobenzene phases

Stability constants ( ₁ ^NB ) of the 1:1 cationic complexes of Li⁺ Na⁺, K⁺ Ca²⁺ Sr²⁺ and Ba²⁺ with benzo-18-crown-6 (B18C6), Ca²⁺ and Sr²⁺ with 18C6 and dibenzo-18C6 and Li⁺, Na⁺, Ca²⁺, Sr²⁺ and Ba²⁺ with dibenzo-24-crown-8 in a nitrobenzene (NB) solution saturated with water (w) were determined at 25°C by ion-transfer polarography. From these values, distribution constants (K _D,ML) of the 18C6-derivative complex cations between the w- and NB-phases were evaluated using the thermodynamic relation:K _D,ML =K ₁ ^NB , whereK (mol dm^–3) is an overall equilibrium constant of the processes related to the complexation in the w-phase. The data on the distribution of the 18C6-derivative complex cations between the two phases and the complexation in the NB-phase were examined on the basis of an increase in the number of water molecules hydrated to the species relevant to these processes. The 18C6 derivatives showed higher solubilities in the NB-phase than in the w-phase by complexing with the univalent-metal ions, while, for the divalent-metal ions, the derivatives showed lower solubilities in the NB-phase.     

Role of stannic phosphate in the uptake of cations. Separation of zirconium from thorium and cadmium from indium at tracer concentrations

The uptake of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Ca²⁺, Cu²⁺, Sr²⁺, Cd²⁺, Ba²⁺, Pb²⁺, Sc³⁺, Co³⁺, Y³⁺, Sb³⁺, Tb³⁺, Zr⁴⁺ and Th⁴⁺ cations at very small concentrations has been studied over a column of stannic phosphate. The exchanger was prepared by mixing H₃PO₄, NaCl and SnCl₄ in suitable proportions and the ratio of PSn, in the product was obtained to be 1.96. Radiochemical separations of carrier free⁹⁵Zr from²³⁴Th and^115mIn, from¹¹⁵Cd have been carried out by adopting a simple chemical procedure over a column of stannic phosphate. The -spectrum analysis showed that the separated products are of high radionuclidic purity. The separation procedures took less than half an hour with quantitative yield.     

Mesitylene based azo-coupled chromogenic tripodal receptors—a visual detection of Ag(I) in aqueous medium

A series of novel tripodal ligands 3a-d, based on a mesitylene anchor, containing aza-thioethers as donor atoms and coupled with 4-(4/3/2-nitrophenyl)azophenol or 4-(2-chlorophenyl)azophenol have been synthesized as chromogenic receptors, which are highly selective for silver(I). The complexation behavior of 3a-d with various metal ions has been evaluated by UV-vis spectrometry in dioxane/water (1:9/v:v) solution at 25 °C. The UV-vis spectra show that the complexation of 3a-c with Ag⁺ have pronounced bathochromic shifts accompanied by a unique color change in the solution from yellow to red, which is visible with the naked eye. The ligands do not show any significant change on addition of other metal ions like Li⁺, Na⁺, K⁺, Sr²⁺, Ca²⁺, Cd²⁺, Zn²⁺, Hg²⁺, Pb²⁺, Ni²⁺, and Cu²⁺ and thus are highly specific and selective for Ag⁺ in the aqueous medium.     

Amphotere Ionenaustauscherharze

Zusammenfassung N-Methyl--aminopropionsäure-Harz bindet infolge Komplexbildung Cu²⁺, UO₂ ²⁺, Bi³⁺, Cr³⁺ und Fe³⁺, während Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺, Pb²⁺, Be²⁺, Tl⁺, NH₄ ⁺, Alkali-, Erdalkali- und Seltenerdionen keine Kapazität zeigen. Durch Variation des pH-Wertes, der Temperatur und Neutralsalzzusatz kann die Selektivität noch erhöht werden. Die analytische Anwendbarkeit wird an Hand von Trennungen binärer Gemische belegt, die oft als Filtrationsverfahren mit geringem Arbeits- und Zeitaufwand durchgeführt werden können.

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Summary N-Methyl--aminopropionic acid (MAP) containing resin binds Cu²⁺, UO₂ ²⁺, Bi³⁺, Cr³⁺ and Fe³⁺ due to its coordinating tendencies, whereas Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺, Pb²⁺, Be²⁺, Tl⁺, NH₄ ⁺, alkalines, alkaline earths and rare earths are not retained. The selectivity can be increased by variation of pH, temperature and inert-salt background. Analytical applications have been shown by separations of binary mixtures. Sometimes these separations are simple and rapid filtration operations.

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1. Mitteilung: Kühn, G., u. E. Hoyer: J. prakt. Chem. (im Druck).

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Dem Direktor des Instituts für Anorganische Chemie, Herrn Prof. Dr. H. Holzapfel, gilt unser Dank für das entgegengebrachte Interesse und die Überlassung von Institutsmitteln.

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Herrn Doz. Dr. R. Hering, Güstrow, danken wir für wertvolle Hinweise.     

Gold(III) Macrocyclic Complexes in Aqueous Solution

Synthesis of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraenatogold(III) perchlorate is described. The behavior of complex cations of gold(III) with macrocyclic ligands—N,N"-bis(2-aminoethyl)-2,4-pentanediiminatogold(III) (A²⁺) and 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraenatogold(III) (B⁺)—is studied in aqueous solutions. The formation of A²⁺and B⁺complexes and the protonation of a B⁺complex are investigated, and the solubility products are determined for perchlorate salts of A²⁺and B⁺cations. The six-membered -diiminate rings of the complex cation B⁺are suggested to be nonequivalent in aqueous solutions: one of them either undergoes intramolecular rearrangement or becomes entirely open.     

Comparison of the Complexation of Open-Chain and Cyclic N2S2 Ligands with Cu+ and Cu2+

The complexation properties of the open-chain N₂S₂ ligands 1–4 are described and compared to those of analogous N₂S₂ macrocycles 5–7 . With Cu²⁺, the open-chain ligands give complexes with the stoichiometry CuL²⁺ and CuLOH⁺, the stabilities and absorption spectra of which have been determined. The ligand field exerted by these ligands is relatively constant and independent of the length of the chain. With Cu⁺, the species CuLH, CuLH²⁺, and CuL⁺ were identified and their stabilities measured. The redox potentials calculated from the equilibrium constants and measured by cyclic voltammetry agree and lie between 250 and 280 mV against SHE. The comparison between open-chain and cyclic ligands shows that (1) a macrocyclic effect is found for Cu²⁺ but not for Cu⁺, (2) the ligand-field strength is very different for the two types of ligands, and (3) the redox potentials span a larger interval for the macrocyclic than for the open-chain complexes.     

p-tert-Butyldihomooxacalix[4]arene/p-tert-Butylcalix[4]arene: Transition and Heavy Metal Cation Extraction and Transport Studies by Ketone and Ester Derivatives

The binding properties of two phenylketones (2a and 3a) and two ethylesters (2b and {3b) derived from p-tert-butyldihomooxacalix[4]arene or from p-tert-butylcalix[4]arene, in the cone conformation, towards transition (Ag⁺, Ni²⁺, Cu²⁺, Co²⁺, Zn²⁺, Fe²⁺ and Mn²⁺) and heavy (Cd²⁺, Hg²⁺ and Pb²⁺) metal cations have been determined by extraction studies with metal picrates and liquid membrane transport experiments with the same salts. The affinity of these ligands for Ag⁺ has also been investigated by ¹H NMR spectroscopy. Both ketones are better extractants than the esters, and show a strong preference for Ag⁺, while Cu²⁺ is the most extracted cation with the esters. ¹H NMR titrations with AgSO₃CF₃ indicate 1 : 1 complexes for all ligands, those with ketones are more stable, on the NMR time scale, than those with esters. Both esters are good carriers for Ag⁺, and 2b exhibits the highest transport rate (4.7 mol h^-1) found until now with dihomooxacalix[4]arene derivatives.     

Solvation of ions. Part XXIX. Ionic conductances in acetonitrile-water and pyridine-water mixtures

The limiting conductance of various salts of Na⁺, Ag⁺, Cu⁺, Cu²⁺ and Ph₄As⁺ in acetonitrile-water (AN-H₂O) and pyridine-water (Py–H₂O) mixtures are reported. Single ion values are calculated for AN-H₂O mixtures using the TATB assumption [_o(Ph ₄ As ⁺) = _o(Ph ₄ B ^–)]. The trends observed for the limiting Walden products (_o) of the electrolytes and individual ions are discussed in terms of specific ion-solvent interactions and the structural effects of the solvent mixtures.Deceased, August 30, 1982.     

Kinetics of uncatalysed and Mn2+ -catalysed oxidation of hydrazine by [MnIV 3 (μ-O)4(bipy)4(H2O)2]4+ ion in aqueous acid

In aqueous acid, hydrazine reduces [Mn^IV ₃(-O)₄(bipy)₄(H₂O)₂]⁴⁺, (1), quantitatively to [Mn^III,IV ₂(-O)₂(bipy)₄]³⁺, (2), and Mn²⁺ if [N₂H⁺ ₅] 2 × (stoichiometric amount). At higher [N₂H⁺ ₅], reduction proceeds up to Mn²⁺. The reduction of (1) to (2) is strongly catalysed by Mn²⁺ and the absorbance (A _t ) versus time (t) graphs have sigmoidal shapes. The graphs become steeper with increasing amounts of added Mn²⁺ and N₂H⁺ ₅, but remain unchanged when [H⁺] is changed. The A _t – t graphs, under various experimental conditions, can all be simulated with a single set of second order rate constants, estimated for the individual steps in a proposed reaction scheme, in which the catalytic action of Mn²⁺ involves a one-electron and a two-electron reduced form of (1), but not (1) itself. The absence of any proton-dependence of the reaction rate refutes an electroprotic mechanism and an inner-sphere mechanism appears to be most likely for the reduction of (1) by N₂H⁺ ₅     

Quantitative chemical analysis on paper: Micro-determination of copper and a mixture of copper and silver

Summary A method has been suggested for the determination of small amounts of copper and of mixtures of copper and silver using filter paper impregnated with silver chloride and sodium carbonate. The method depends on competition between copper and silver ions to form complexes with cyanide added to the paper. The area of the spot produced by conversion of AgCl into Ag(CN)₂ ^– is measured by weight, and is inversely proportional to the amount of copper present, since the Cu(CN)₄ ^3– complex is preferentially formed. The silver present is determined separately, and the amount of copper calculated.The determination is possible in the presence of Bi³⁺, C³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, Al³⁺, Sn²⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^–, and SCN^–.The determination is impossible in the presence of I^–, I₂, Zn²⁺, Cd²⁺, Hg₂ ²⁺, Co²⁺, or Ni²⁺.The method permits the determination of 4–30g of copper and 8–60g of silver with an accuracy of 2%.

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Zusammenfassung Eine Methode zur Bestimmung kleiner Kupfermengen und von Kupfer-Silber-Gemischen mit Hilfe von Filtrierpapier wird vorgeschlagen, das mit Silberchlorid und Natriumcarbonat imprägniert ist. Sie beruht auf der Konkurrenz zwischen Kupfer und Silber bei der Komplexbildung mit Cyanid, das man auf das Papier aufbringt. Das Flächenausmaß des durch Komplexierung des Silbers gebildeten Fleckens wird gravimetrisch bestimmt. Es ist umgekehrt proportional zur Menge anwesenden Kupfers, da [Cu(CN)₄]^3– bevorzugt gebildet wird. Das Silber wird getrennt bestimmt und so die Kupfermenge berechnet.Die Bestimmung ist möglich in Gegenwart von Bi³⁺, Cr³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, A1³⁺, Sn²⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^– und SCN^– und nicht möglich in Gegenwart von J^–, J₂, Zn²⁺, Cd²⁺, Hg₂ ²⁺, Co²⁺ oder Ni²⁺.4 bis 30g Kupfer sowie 8 bis 60g Silber können mit einer Genauigkeit von 2% bestimmt werden.

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Résumé On propose une méthode pour doser de petites quantités de cuivre et de mélanges de cuivre et d'argent, à l'aide de papier-filtre imprégné de chlorure d'argent et de carbonate de sodium. La méthode dépend de l'effet compétitif entre les ions cuivre et argent pour former les complexes avec le cyanure déposé sur le papier. La surface de la tache formée en transformant le chlorure d'argent en Ag(CN)₂ ^– est mesurée par pesée et est inversement proportionnelle à la quantité de cuivre présent, puisque le complexe Cu(CN)₄ ^3– se forme préférentiellement. L'argent présent est dosé séparément et la quantité de cuivre s'en déduit par calcul.Le dosage est possible en présence de Bi³⁺, Cr³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, Al³⁺, Sc³⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^– et SCN^–.Le dosage est impossible en présence de I^–, I₂ ^–, Zn²⁺, Cd²⁺, Hg²⁺, Co²⁺ ou Ni²⁺. La méthode permet le dosage de 4 à 30g de cuivre et de 8 à 60g d'argent avec une précision de 2%.

     

Crystal Chemistry of the M11+,2+–M22+,3+–(H)‐Arsenites: the First Cadmium(II) Arsenite,Na4Cd7(AsO3)6

The crystal structures among M1–M2–(H)‐arsenites (M1 = Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ca²⁺, Sr²⁺, Ba²⁺, Cd²⁺, Pb²⁺; M2 = Mg²⁺, Mn^2+,3+, Fe^2+,3+, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺) are less investigated. Up to now, only the structure of Pb₃Mn(AsO₃)₂(AsO₂OH) was described. The crystal structure of hydrothermally synthesized Na₄Cd₇(AsO₃)₆ was solved from the single‐crystal X‐ray diffraction data. Its trigonal crystal structure [space group R$\bar{3}$ , a = 9.5229(13), c = 19.258(4) Å, γ = 120°, V = 1512.5(5) ų, Z = 3] represents a new structure type. The As atoms are arranged in monomeric (AsO₃)^3– units. The surroundings of the two crystallographically unique sodium atoms show trigonal antiprismatic coordination, and two mixed Cd/Na sites are remarkably unequal showing tetrahedral and octahedral coordinations. Despite the 3D connection of the AsO₃ pyramids, (Cd,Na)O_x polyhedra and NaO₆ antiprisms, a layer‐like arrangement of the Na atoms positioned in the hexagonal channels formed by CdO₄ deformed tetrahedra and AsO₃ pyramids in z = 0, 1/3, 2/3 is to be mentioned. These pseudo layers are interconnected to the 3D network by (Cd,Na)O₆ octahedra. Raman spectra confirmed the presence of isolated AsO₃ pyramids.     

Interaction of Na+, K+, Li+ and Ca2+ ions in Tris-HCl buffer substrate with monolayers of phosphatidic acid and homologous phosphatidic acid alkyl esters

The interaction of ions (Na⁺, K⁺, Li⁺, Ca²⁺) with monolayers of phosphatidic acid alkyl esters (alkyl = methyl, ethyl,n-propyl,n-pentyl) were investigated at the air/water interface on Tris-HCl buffer, as well as on the electrolytes containing subphases.Qualitatively it can be stated that there are no considerable interactions between Na⁺ ions in the substrate and the head groups of phosphatidic acid esters in the monolayers. On the whole, the modification of the shape in the /a and v/a isotherms ( ^s = film pressure, v ^s = film potential) of the homologous phosphatidic acid esters as a function of the length of the ester group on the subphase containing NaCl, KCl, and LiCl corresponds to that on Tris-HCl buffer without admixture of electrolytes.On the other hand the strength of interaction between Ca²⁺ ions and the homologous phosphatidic acid esters depends on the length of the ester group. The film-condensing effect of Ca²⁺ ions becomes smaller with increasing length of the ester group.