Reaction of mercury(II) and xylenol orange-I Effect of the buffering media

The influence of the buffering medium on the reaction of Hg(II) with Xylenol Orange has been studied. Amine-type compounds are complexed by Hg(II)/Xylenol Orange with a sharp hyperchromic effect on the reagent itself, at 590 nm, but complex formation of Hg(II)/Xylenol Orange in non-amine-type buffer, such as citric acid-phosphate, gives a hypochromic effect on Xylenol Orange at 580 nm. Hg(II) is determined at pH 7.5 in two ranges of concentration, 2-9 ppm in citrate buffer, measured at 580 nm ( = 2.50 x 10(4)), and 6-11 ppm in hexamine buffer, at 590 nm ( = 4.18 x 10(4)).     

Crystal structure and magnetic structure of TbOOH

The monoclinic modification of terbium oxide hydroxide, TbOOH, was prepared using hydrothermal technique. The crystal structure was investigated by three-dimensional single-crystal X-ray analysis and was refined to a conventional R-value of 8.1%. The space group is $\text{P2}{}_1\text{m}$, No. 11, with a = 6.04 Å, b = 3.69 Å, c = 4.33 Å, and β = 109.0°. The terbium atom is seven coordinated with oxygen atoms, and the structure is not hydrogen bonded.The compound is antiferromagnetic with a Néel temperature of 10°K. Neutron diffraction powder patterns were measured at 300°K and 4.2°K. The magnetic super lattice reflections were indexed on the basis of a monoclinic unit cell with the dimensions a_M = 2a, b_M = b, c_M = c, and β_M = β, where a, b, c, and β are the dimensions of the chemical unit cell. The structure contains two independent magnetic atoms. A nonclinear antiferromagnetic arrangement of the spins describes the magnetic structure. The spin at one atom has an angle of 43° with the ac plane and the projection of the spin on the ac plane has an angle of 59° with the a axis. The spin on the other atom has an angle of ?43° with the ac plane, the projection having the same angle of 59° with the a axis.     

Semiempirical calculations on triplet and doublet states

Restricted open-shell SCF calculations are carried out on triplet states of electron systems and doublet states of some of their ions. The results are compared with the ones obtained by limited configuration interaction and by the use of Koopman's theorem. For some examples open-shell SCF wavefunctions are expanded into linear combinations of Slater determinants representing configurations built from closed-shell SCF orbitals. This allows a more detailed comparison of the different methods of calculation.

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Zusammenfassung Berechnungen nach der beschränkten SCF Methode für offene Schalen werden an Triplettzuständen von -Elektronensystemen und Dublettzuständen einiger ihrer Ionen ausgeführt. Die Resultate werden mit denjenigen verglichen, welche die beschränkte Konfigurationswechselwirkung und der Satz von Koopmans liefern. Die SCF Wellenfunktionen für offene Schalen werden, für gewisse Beispiele, in Linearkombinationen von Slater-Determinanten entwickelt, welche aus SCF Orbitalen für geschlossene Schalen aufgebaut sind und verschiedene Konfigurationen darstellen. Dies erlaubt einen eingehenderen Vergleich der verschiedenen Berechnungsmethoden.

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Résumé Des calculs selon la méthode SCF avec restriction pour les couches ouvertes sont effectués sur les états triplets de systèmes d'électrons et sur les états doublets de certains de leurs ions. Les résultats sont comparés à ceux obtenus par la méthode d'interáction de configurations limitée et par l'emploi du théorème de Koopmans. Pour certains exemples les fonctions SCF à couches ouvertes sont développées en combinaison linéaire de déterminants de Slater représentant des configurations bâties à partir d'orbitales S.C.F. de couches fermées. Cela permet une comparaison plus détaillée des différentes méthodes de calcul.

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Presented in parts at the Theoretical Chemistry Symposium in Vienna, March 1967.     

Neue stellungsisomere reineckesalzähnliche Verbindungen mit Toluidinen

Zusammenfassung Es wurden eine Reihe von Substitutionsreaktionen mit entwässertem K₃[Cr(NCS)₆] und aromatischen Aminen, ohne Verwendung von Lösungsmitteln, durchgeführt. Es wurde beobachtet, da die sehr schwachen Basen mit p_K-Werten 14–16, wie die isomeren Mono- und Dinitro-aniline, die Anthranil- und Sulfanilsäuren, für diese Substitutionsreaktionen ungeeignet sind. Die Alkyl-anilinderivate, wie daso-, m- undp-Toluidin (p_K=10–11) bilden dagegen leicht reineckesalzähnliche Verbindungen: Amin· H[Cr(Toluidin)₂(NCS)₄]. Die Zusammensetzung der neuen Komplexanionen wurde bei einer Reihe von doppelten Umsetzungsreaktionen mit den Chlorhydraten einiger heterocyclischen Aminen festgestellt.Für die Klärung einiger Strukturfragen wurden spektrophotometrische Untersuchungen im UV und IR durchgeführt und die thermische Stabilität bzw. der Mechanismus des Pyrolysenvorganges auf thermogravimetrischem Wege verfolgt.

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Substitution reactions of anhydrous K₃[Cr(NCS)₆] with aromatic amines without applying of solvents were studied.It was observed, that the very weak bases (pK-values 14–16, e.g. isomeric mono- and dinitro-anilines, the anthranilic and sulfanilic acids) are unsuitable for substitution reactions. The alkylaniline derivates e.g.o-, m- andp-toluidine (pK=10–11) form easily reineckesalt analogous compounds: Amin· ·H[Cr(toluidine)₂(NCS)₄]·The formula of the 3 new complex anions: [Cr(toluidine)₂ (NCS)₄]- was established by preparative methods, with a series of double decomposition reactions, using chlorohydrates of some heterocyclic amines for this purpose. From spectroscopical investigations (UV and IR) some structural problems are resolved and discussed.The thermal stability and the mechanism of pyrolysis of these salts was studied by thermogravimetric analysis.

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Mit 8 Abbildungen     

Calcul théorique des énergies de divers arrangements géométriques de la molécule (η5-C5H5)2TiCl2

The molecular energy of the complex (η⁵-C₅H₅)₂TiCl₂ has been calculated for experimental geometry and for several hypothetical forms by a semi-empirical CNDO/2 approach. The energy difference between experimental (quasi-tetrahedral) geometry and a planar geometry is ca. 20 kcal mol^?1. This difference is sufficiently high to explain the difficulty of the inversion process.     

Retention of85Sr and147Pm on insoluble hydroxides and phosphates prepared by the sol-gel procedure

Retention of strontium and promethium on hydroxides (hydrated oxides) and phosphates of iron and chromium prepared by the sol-gel method was studied. The sorption was determined under static conditions depending on the pH of the solution. The sorption isotherms and retention were investigated under dynamic conditions.     

Intramolecular "Aryl-metal chelate ring" pi,pi-interactions as structural evidence for metalloaromaticity in (aromatic alpha,alpha'-diimine)-copper(II) chelates: molecular and crystal structure of aqua(1,10-phenanthroline)(2-benzylmalonato)copper(II) three-hydrate

By reaction of Cu(2)CO(3)(OH)(2), 2-benzylmalonic acid (H(2)Bzmal), and 1,10-phenanthroline (phen), [Cu(Bzmal)(phen)(H(2)O)] x 3H(2)O (compound 1) has been obtained and characterized by thermal, spectral, magnetic, and X-ray diffraction methods. The molecular structure of 1 is remarkably similar to that of [Cu(Bzmal)(bipy)(H(2)O)] x 2H(2)O (compound 2, bipy = 2,2'-bipyridine). In both complexes, the aryl(Bzmal) ring produces an unexpected pi,pi-stacking interaction with the Cu(II)-(aromatic alpha,alpha'-diimine) chelate ring, at an average distance d(pi)(-)(pi) of 3.40 A, involving roughly parallel and smoothly slipped rings. This insight is discussed as new structural evidence for metalloaromaticity of Cu(II)-(aromatic alpha,alpha'-diimine) chelate rings. Interestingly, 1 recognizes itself by a weak intermolecular pi,pi-stacking interaction between aryl(Bzmal) ligands to give pairs of complex molecules. In contrast, there is an intermolecular pyridyl-pyridyl pi,pi-stacking interaction also forming pairs of complex molecules in 2.     

Automation of the gas analysis of14C-labelled compounds utilizing a piston-type counter tube

In this paper an automatic apparatus designed for the radioactivity measurement of¹⁴C-labelled organic compounds in the gaseous phase is described. The labelled organic compounds are combusted in a mixture of argon and oxygen. After combustion the oxygen content of the gas is eliminated by passing it through a copper packing. The water and heteroelements present are also removed and the radioactive carbon dioxide gas is swept by argon carrier gas into a piston-type counter tube. In the counter tube the piston forming a dividing wall moves forward in accordance with the rate of combustion and sweeping, and thus sucks the gases leaving the combustion tube into the effective tube volume. The anode wire is carried by a reel located in the piston and a spring device ensures its stretched state. At the end of the sweeping period methane is fed into the counter tube and the activity of the argon—methane—carbon dioxide mixture is measured in the limited proportional region. Manual and automatic operation is possible. The piston-type counter tube provides possibility for strandardization by means of extrapolation and for measurement of absolute activities.     

Protonation et hydrolyse d'enamine. Epimerisation des immoniums intermediaires

At pH 5 (AcOHAcONa) protonation of the enamine of 3,6,6-trimethylnorpinane 2-one (3-methylnopinone) yields the cis immonium ion 6 (X  OAc), which isomerizes to the thermodynamically more stable trans immonium ion 6′ (X  OAc). Under more strongly acid conditions (aqueous hydrochloric or perchloric acids), the enamonium salts 7 (X  Cl or ClO₄) are formed; these isomerize, with a rate increasing with decreasing acidity to the cis immonium salts 6, stable under these conditions. Epimerization of the cis salt 6 (X  Cl), occurs in ethereal hydrogen chloride, the rate increasing also with decreasing acidity. At pH 5, hydrolysis of the enamine yields 3-methylnopinone, the proportion of the less thermodynamically stable trans isomer increasing with a rise in reaction temperature.     

Some investigations on the photostabilization of polypropylene

The effect of substituted hydroxybenzophenone, benzotriazole and organic metal complexes on the photooxidation of PP films has been studied. It has been established that NiDBTC added in 1.0 wt. % is the most effective photostabilizer.While in the case of other stabilizers there is a slight increase in the Co content even during the induction period, with the application of NiDBTC practically no oxidation can be observed before the stabilizer completely disappears. This means that NiDBTC inhibits the photooxidation of the polymer even in low concentration.

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