A potentiometric study of the water-soluble silver(I) complexes of n,n'-bis(2-hydroxyethyl)dithiooxamide : Part III. Determination of the different species

Silver(I) and N,N'-bis(2-hydroxyethyl)dithiooxamide (H₂X) in acidic solutions, form a series of water-soluble polynuclear complexes. These complexes can be represented by two general formulae: H_2qAg_pX_q and H_2q-1Ag_pX_q with q=1,2,3 and p=q, q-1.     

The vibrational analysis of methylarsonic acid,trideuteromethylarsonic acid and their anions

Raman and IR spectra of methylarsonic acid, CH₃AsO₃H₂, trideuteromethylarsonic acid, CD₃AsO₃H₂ and their anions in aqueous solution and the solid state are discussed. Some results of a general valence force field and a Urey-Bradley force field are reported.     

Molecular polarizability and the three-dimensional structure of substituted trinitromethanes

A method is suggested for estimating the assymmetry of molecules based on analysing their polarizability ellipsoids. This method is applied to fluoro-, chloro- and bromo- trinitromethanes and to 1,1,1-trinitroethane. The effective angles of rotation of nitro groups have been determined.     

Far-infrared photoconductivity spectra of quenched-in acceptors in germanium: Chemical effects on the SA1 acceptors

Far-I.R. photoconductivity reveals the existence of at least four different kinds of SA₁ acceptors in germanium quenched from T > 800 each acceptor producing two or more hydrogenic excitation line series. One acceptor is correlated with the presence of Ni, another one with strong Cu contamination. The two other acceptors, which we call ‘normal’ and ‘shifted’, occur in samples quenched without intentional doping. The experiments indicate that the SA₁ acceptors in germanium are impurity complexes involving fast diffusing elements. We discuss a model according to which the SA₁ acceptors would be interstitial-substitutional pairs of transition metals. In particular, we propose to assign the ‘normal’ SA₁ acceptors to Fe_I-Cu_S pairs.     

The effect of silver on the Raman spectrum of α-copper phthalocyanine

The Raman spectrum of insoluble α-copper phthalocyanine is enhanced relative to a barium sulphate standard which the compounds are dispersed in a silver matrix. The improvement in signal-to-noise ratio is very much greater when the silver matrix is not diluted by the standard. Silver produces a larger effect than other matrices.     

Analytical chemistry in Belgium: an historical overview

The people, places and political influences of importance in the history of chemistry in Belgium have been reviewed with particular reference to analytical chemistry. Correspondence: D. Thorburn Burns, The Science Library, The Queen’s University of Belfast, Belfast, BT9 5AG Northern Ireland, UK     

NMR spectra of meta-difluorobenzene in nematic solvents: molecular geometry and anisotropy of the indirect fluorine-fluorine coupling

Nuclear magnetic resonance spectra of 1,3-difluorobenzene in thermotropic and lyotropic nematic solvents have been measured and interpreted. The geometrical data calculated from the dipolar couplings are compared with those obtained from microwave spectra and from a recent electron diffraction experiment. Evidence has been found of a small anisotropy in the indirect fluorine-fluorine coupling.     

Vibrational study in the low frequency region (700—100 cm−1) of phosphine monosubstituted group VI B metal carbonyls

IR, FIR and Raman data in the low-frequency region (700-100 cm^?1) are presented for a number of Cr, Mo and W carbonyls of the type R₃PM(CO)₅, with the ligands (CH₃)₃P, (C₂H₅)₃P, (C₆H₅)₃P and (X—C₆H₄)₃P (X = F, Cl, CH₃), and for three further chromium carbonyls LCr(CO)₅, with the ligands PCl₃, C₆H₅PCl₂ and (C₆H₅)₂PCl. The observed δ(MCO) modes are assigned together with all ν(MC) and ν(MP) fundamentals. The behavior of these modes is discussed in relation to the different ligands and in comparison with known ν(CO) data. The dependence of ν(MP) on σ and π properties of the ligands is investigated.     

Analytical study of two diazotization-coupling reactions. Application to the determination of nano-amounts of nitrite in water

Aluminium has been determined in various standard rocks by 14-MeV neutron activation analysis. The induced ²⁷Mg activity (1.01-MeV photopeak) was counted with a multichannel analyser, equipped with Barto?ek's dead-time stabilizer system. Aluminium standards were prepared by mixing silica and alumina. Correction was made for the interfering reaction ³⁰Si(n,α)²⁷Mg by counting the 1.78-MeV peak, 10 min after irradiation. The mean coefficient of variation on a single determination was 2.8% at the 6–10% aluminium level.