The equilibrium partition coefficients of iodine species between water and gas phase as a function of iodine concentration have been measured. At very low concentrations the partition coefficients have been determined to be ∼7800 and ∼1650 at 21 and 72°C, respectively. The results of chemical analyses for iodine species in both phases provide convincing evidence of the existence of hypoiodous acid (HIO) in both phases in low concentration experiments. The partition coefficient data are used to estimate the equilibrium constant and some thermodynamic properties of HIO.
The photochemical decomposition of Nd3+/EDTA and Ho3+/EDTA has been carried out at 300 nm, and followed by changes within the hypersensitive absorption transitions of these ions. It was found that a single decarboxylation of the EDTA ligand occurred, and CO2 gas was evolved. The reaction terminates after approx. 1 mol of CO2 per mole of EDTA is produced, since the photoproduct absorbs strongly at 300 nm. Initial quantum yields were found to vary with pH, but averaged between 0.1 and 0.5 mol/Einstein.
The electroreduction of oxopentachlorocomplex of Tc(V) has been studied in 4 M HCl solution by simultaneous coulometry and spectrophotometry. The nature of the products as well as the kinetics of the reduction process and consequent complex equilibria are discussed.
Two new forms of microcrystalline thorium arsenate have been synthesised. They have been characterised as Th(HAsO4)2·4H2O and Th(HAsO4)·2.5H2O by chemical analysis and thermal, X-ray, IR and ion exchange studies. The interlayer distances are: Th(HAsO4)2·4H2O: 8.23 Å and Th(HAsO4)2·2.5H2O: 8.59 Å. However, thermally and chemically, both these exchangers are less stable than Th(HAsO4)2·H2O; Th(HAsO4)2·2.5H2O being more stable than Th(HAsO4)·4H2O. The maximum lithium ion uptake and the corresponding arsenate released, respectively are: 1.75 and 1.20 mmol/g for Th(HAsO4)2·4H2O at pH 9.0 and 3.42 and 0.28 mmol/g for Th(HAsO4)2·2.5H2O at pH 11.8. For both exchangers, the loss of zeolitic water as well as that released on formation of thorium pyroarsenate takes place in one step between 383 and 773 K.
Amorphous and micro-crystalline α- and γ-zirconium acid phosphates have been investigated by the ESCA technique. α-zirconium phosphate has been also studied as a single crystal. Both the B.E. of zirconium and phosphorous electrons in zirconium phosphates are slightly higher than those reported for zirconium derivatives and trivalent metal phosphates, indicating a stronger polarization of the ZrO and PO bonds. Furthermore, it seems that some ESCA features of the zirconium phosphates investigated are structure dependent. However, no definitive conclusions have been drawn because of the lack of knowledge of the “charging-up” phenomena in protonic conductors such as zirconium phosphates. Satellite structures have been observed in the P2s, P2p, Zr3d and Zr4p regions. The position and the intensity of these “shake-up” effects are again dependent on the nature of the examined phase and they seem to be due to the presence of electron defect structures induced by X-rays or already present in the original samples.
The kinetics of crystallization of calcium sulfate dihydrate has been studied in ammonia solutions at 65° as a function of supersaturation, ionic strength and added electrolytes. The rate of reaction follows an equation first-order in relative supersaturation with respect to the calcium concentration under conditions in which the concentration of sulfate ion is effectively constant during the reaction. The crystal growth proceeds towards equilibrium much more rapidly as compared with the process at low ionic strengths. Copper ion and anions such as phosphate, carbonate and molybdate, reduce the reaction rate and also appear to influence the kinetics of crystallization. Calcium sulfate hemihydrate, anhydrite and calcium carbonate crystals are effective nucleators for the growth of gypsum under the conditions of this work.
The preparation of the complex Fe(ppi)3(NCS)2 (where ppi = N-phenyl-2-pyridinaldimine) is described. Mössbauer and magnetic susceptibility of this compound was studied in the temperature range between 298 and 78 K and clearly indicate a temperature induced high-spin(5T2)-low-spin(1A1) transition.
Dinuclear complexes with μ-cyano ligand of formula [(aa)2FCrNCM(CN)3] have been obtained by heating trans-[CrF(H2O)(aa)2][M(CN)4] (aa = ethylenediamine (en); 1,3-propanediamine (tmd); M Ni(II), Pd(II), Pt(II). Chemical analyses, conductivity measurements and electronic and IR spectra justify the formulation proposed. X-Ray diffraction indicates isomorphism for the three mixed complex salts of en, and for the tmd salts. The amine part of the en complexes undergoes a trans → cis change of configuration during the formation reaction; this change is not observed for the tmd complexes. The cis-bis (ethylenediamine) fluoro (tetracyanoplatinate(II)-N) Chromium(III): Cis-[(en)2FCrNCPt(CN)3] shows Pt-Pt interaction both in the solid state and in solution.
The yield of 166Dy produced via the double neutron capture of 164Dy was determined by the activation method. The γ-emission probabilities in the decay of 166Dy and its daughter 166Ho were measured and used for the determination of the yield. The reactor-neutron-capture cross sections of 165Dy isomers were deduced from the dependence of the yield on the length of the irradiation time. Obtained cross sections were 2000 ± 600 b for the metastable state and 3530 ± 330 b for the ground state, respectively, with the choice of the Westcott epithermal index r · √(T/T0) = 0.017. The ratio of the cross sections between the pair of isomers was discussed together with the cross section ratios of other isomer pairs on the basis of the compound formation model.
The electrochemical characterization of redox couple UO22+/UO2+ in LiClKCl eutectic at 450°C has been carried out with normal pulse polarography on Pt, Au, tin oxide and glassy carbon electrodes. Pt and Au electrodes immersed in the melt containing UO22+ result in mixed potential systems, being corroded considerably with the simultaneous reduction of UO22+ at the open potentials. While the latter two electrodes give well-defined, two steps reduction waves; the first one is a reversible, one-electron transfer with E12 = −0.487 ± 0.005 V vs 1M Pt(II)/Pt, and the second wave, whose onset potential largely depends on the kind of electrode, is ascribed to a succeeding one-electron transfer yielding UO2 deposits. Pulse polarography on GCE, which has the largest nucleation overvoltage among them, was proved suitable for detection of the intermediate UO2+.
A quantitative study of the kinetics of the thermal decomposition of U(BH4)4 in the gas phase is described. The decomposition is monitored by changes in the infrared absorption spectrum at different temperatures. Decomposition is found to be of 1st order in the 130–170†C temperature range and of 2nd order in the 100–120°C temperature range. The reaction rate constants and activation energies are determined for each temperature region. It is shown that the shift from higher order to a lower order as the reaction temperature increases is consistent with the Lindemann theory.
The water soluble “picket fence” porphyrin, meso-tetra(α,α,α,α-ortho-(N-methyl-isonicotinamidophenyl)) porphyrin, its three rotational isomers, and the corresponding para and meta derivatives were synthesized. The ortho substituted compounds were one-hundred times less basic and less reactive with metal ions than the para or meta isomers. The reduction potentials of the free base porphyrins indicated electronic interaction between the porphyrin ring and the ortho substituent groups in the isonicotinamidophenyl compounds.
The cyanobenzoates of Cu(II) have been prepared and their magnetic and spectral properties examined. Although Cu(II) compounds of ortho-substituted benzoic acids crystalline from aqueous solutions mostly as monohydrates with dimeric structure, Cu(II) o-cyanobenzoate precipitated out as a dihydrate with the magnetic and spectral properties of a monomer whilst its anhydrous form has the characteristics of a dimer. Anhydrous Cu(II) m-cyanobenzoate behaves as a dimer and was isolated from the same solution along with the monohydrate which consists of a mixture of dimer and or polymer. Dihydrated Cu(II) p-cyanobenzoate and the basic salt, Cu(p-CNC6H4COO) (OH), comprise monomeric or polymeric molecules.
