4-Cyanoaniline complexes with transition metal(II) halides

Summary Coordination compounds formed by the interaction of manganese(II), cobalt(II), nickel(II) and copper(II) chloride and bromide with 4-cyanoaniline (4-CA) have been prepared and characterized by molar conductance, magnetic susceptibilities, electronic and i.r. spectral measurements down to 200 cm^–1 in the solid state. The isolated complexes are M(4-CA)₂X₂ except for nickel(II) bromide which is NI(4-CA)₄Br₂. I.r. spectra, indicate that 4-CA, though a potentially bidentate ligand, nevertheless acts only as a terminally aniline (NH₂) bonded monodentate ligand in all the complexes. Tentative stereochemistries of the complexes have been suggested in the solid state.     

The crystal structures of strontium exchanged sodium titanosilicates in relation to selectivity for nuclear waste treatment

The exchange of Sr²⁺ into the proton form of the ion exchanger Na₂Ti₂O₃(SiO₄)·2H₂O was examined by means of X-ray powder diffractometry. This material has a sitinakite framework structure enclosing a tunnel parallel to the c-axis. At the 25% Sr²⁺ exchange level, the strontium ion was found near an oxo-framework oxygen midway between two adjacent faces of the tetragonal unit cell. It is bonded to five framework oxygen atoms and five water molecules. The Sr coordination number (CN) is reduced to nine in a sitinakite phase for which 16 mol% of the Ti (IV) was replaced by Nb (V). It has been previously shown that at a higher level of Nb substitution (25 mol%), the CN was further reduced to seven. This change in CN is opposite to what is observed for Cs⁺ where the CN is eight for the Ti phase and 12 for the Ti_1.5Nb_0.5 phase. The changes in CN are accompanied by a series of changes in the space group to accommodate occupancy of the exchange sites by the cations and water molecules. The selectivity of exchanger is governed by the strength and number of bonds formed by the exchange reactions.     

Synthesis and spectroscopic studies of nickel(II) chalcogenolates derived from 1,2-diarylchalcogenolato-o-xylene

Nickel(II) chalcogenolate complexes [Ni(L-L)₂(dppe) Cl₂] (1, 2) have been prepared in high yields by reacting 1,2-diarylchalcogenolato-o-xylene, o-C₆H₄(CH₂EAr)₂ (E = Se or Te; Ar = Ph, C₆H₄OMe-4 and C₆H₄OEt-4), generated in situ, with Ni(dppe)Cl₂ [dppe = 1,2-bis(diphenylphosphino)ethane] in benzene. The structures were established by elemental analyses, molar conductance, i.r. and Raman, electronic ¹H- and ³¹P-n.m.r. and mass spectral data. The analytical and spectroscopic data are consistent with an octahedral geometry around nickel in (1) and (2). The ³¹P-n.m.r. spectra indicate their cis configuration in solution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Kinetics of the oxidation of acrylic acid by ce(IV) in acid perchlorate solution

The kinetics of oxidation of acrylic acid by Ce(IV)-perchlorate in perchloric acid were studied by following the rate of dissappearance of Ce(IV). The reaction order was zero with respect of Ce(IV) and unity with the acrylic acid. The addition of [H⁺] shows a proton catalysis and no salt effect is observed. Spectrophotometric studies do not reveal the formation of intermediate complex and thus a mechanism postulating the hydrolysis of the acid is suggested which undergoes first oxidation by the reactive species of Ce(IV). Thermodynamic parameters have also been calculated.     

Time resolved resonance Raman observation of the extreme protonation forms of a radical zwitterion in water

The reactions of the aqueous proton with the zwitterionic p-aminophenoxyl radical in strongly basic to extremely acidic aqueous solutions have been investigated using time-resolved resonance Raman spectroscopy. The dynamic stability of the different protonation forms of the radical, observed on the microsecond time scale in this work, has been achieved by controlling the proton exchange rate in water. In strongly acidic solutions we observe a rare ring-H+ bonded dication species, a key intermediate in the amine hydrolysis. The neutral p-aminophenoxyl radical undergoes NH2-deprotonation in strongly basic aqueous solutions, which has no analogues in closed-shell amines.     

Dielectric properties of mixtures of acetylene tetrachloride with toluene and acetone

Relative permittivities are reported for binary liquid mixtures of acetylene tetrachloride (ATC) with toluene and acetone at 35°C. Measurements of refractive indices have also been made for the mixtures. The values of the quantity , the deviations of the relative permittivities of these mixtures from ideality, have been calculated. The negative values of obtained for ATC+ toluene mixtures may be explained as being due to a decrease in the degree of alignment of the molecular dipoles with changing composition of the mixture, whereas the positive values of obtained for ATC+acetone mixtures are attributed to the formation of molecular complex between acetone and CHCl₂CHCl₂. The values of the Kirkwood correlation parameter g for both sets of mixtures have been calculated using the relative permittivity data.     

Equilibrium studies on some heteroligand hydroxo complexes of lanthanons with iminodiacetic acid and citraconic or maleic acid

Mixed-ligand ternary complexes of La(III), Pr(III), Nd(III), Gd(III), and Dy(III) with iminodiacetic acid (IMDA) and citraconic (CCA) or maleic acid (MIA), have been studiedpH-metrically. Their formation takes place through the stepwise addition of the secondary ligand (IMDA) to the initially formed 1:1, Ln(III)—CCA/MIA binary species. The resulting ternary complexes undergo hydrolysis to form their hydroxo derivatives simultaneously. The stability constants of the hydroxo species are calculated for constant temperature (27 ± 1°C) and ionic strength (I=0.1M KNO₃). The relative order of stability is: La(III)

Gleichgewichtsuntersuchungen an einigen Heteroliganden-Hydroxo-Komplexen von Lanthanid-Ionen mit Iminodiessigsäure und Citracon- oder Maleinsäure

Zusammenfassung Es wurden ternäre Komplexe von La(III), Pr(III), Nd(III), Gd(III) und Dy(III) mit gemischten Liganden [Iminodiessigsäure (IMDA) und Citraconsäure (CCA) oder Maleinsäure (MIA)] mittelspH-metrischer Methoden untersucht. Diese Komplexe werden über die stufenweise Addition des Sekundärliganden (IMDA) zu den primär gebildeten 1:1 Ln(III)—CCA/MIA Spezies gebildet. Zugleich erleiden die resultierenden ternären Komplexe Hydrolyse und gehen in die entsprechenden Hydroxo-Komplexe über. Die Stabilitätskonstanten der Hydroxo-Komplexe wurden für konstante Temperatur (27 ± 1°C) und Ionenstärke (I=0.1M KNO₃) berechnet. Die relative Reihung bezüglich der Stabilitäten ergab sich folgendermaßen: La(III)     

Étude des isomères (CO)Fe(PF3)4

Assignments of a certain number of vibrational bands of (CO)Fe(PF₃)₄ are made with reference to the C_3v and C_2v isomers. A study of the Raman and spectra at low temperature revealed that in the solid state only one isomer exists. Furthermore, a comparative study of liquid (CO)Fe(PF₃)₄ and HCo(PF₃)₄ of molecular symmetry C_3v was made. These two approaches made it possible to determine the difference in enthalpy between the two isomers of the iron complex (+0-52±0.05 kcal.mole⁻¹) in the liquid state, as well as to verify the assignments proposed previously. The greater stability of the C_2v isomer is discussed.     

Scattering of fast electrons and X-rays from molecules: CH4 and C2H2

Self-consistent-field (SCF ) wave functions are used to calculate cross sections for the elastic and inelastic scattering of fast electrons and x-rays from CH₄ and C₂H₂ molecules. The effects of basis set choice and free rotation on these cross sections are investigated. The utility of an approximate scheme to correct SCF inelastic cross sections for the effects of electron correlation is examined. The probability density for the interelectronic distance, or radial intracule density, is obtained and discussed.     

Chloride analysis in magnesium metal using ion chromatography with conductometric detection

A simple, rapid and accurate method for the determination of chloride in magnesium metal has been developed. The quantitative determination of chloride was accomplished by anion exchange chromatography with conductometric determination. A Metrosep Anion Dual 2 analytical column connected in series with a Metrosep RP guard column was used for chloride separation. A solution containing a mixture of 1.3 mM Na2CO3 and 2 mM NaHCO3 was used as eluent. The method requires a sample dissolution using nitric acid. The limit of detection for the determination of chloride is 50 mg kg(-1) and the relative standard deviation was 5% for the overall method. The recovery of chloride added was 99-102%. No interference was observed from either the closely eluting "system peak" or the nitrate peak in the determination of chloride.