[en] ³⁵Cl NQR spectra in SnCl₄·2Me₂O and SnCl₄·2Et₂O have been observed. Three crystal modifications of SnCl₄·2Me₂O have been found. A cis geometry is suggested for one of them, and a trans geometry for the remainder. A transformation between the cis and trans isomers in the solid state is indicated. The Zeeman effect on single crystals of cis-SnCl₄·2Me₂O and SnCl₄·2Et₂O has provided detailed information on bond angles and bond character. It is confirmed that the molecular geometry of cis-SnCl₄·2Me₂O belongs to the C₂ group and that SnCl₄·2Et₂O has a trans geometry. The η values of the Cl atoms in cis-SnCl₄·2Me₂O are negligibly small and those of the Cl atoms in SnCl₄·2Et₂O are 0.11. The relatively small η values for the latter are ascribed to π bonding between the Sn and Cl atoms. (author)

[en] The dielectric solvent effect on the ²⁹Si NMR chemical shifts of some chlortosilanes is calculated by means of the finite perturbation theory within the CNDO/2 framework using the solvation theory which is employed to estimate specific solute-solvent bonded interactions as a function of the dielectric constant of the medium. The calculated variations are reasonably compared with the gross trend of the observed solvent effects of ²⁹Si chemical shifts. Further, the origin of the dielectric solvent effect is discussed. (author)

[en] The ultraviolet spectrum observed in γ-irradiated liquid nitrogen containing a small amount of oxygen has been ascribed to ozone. The εG value was obtained. The dose rate effect on the yield of ozone was observed. The value of ε_mG was inversely proportional to the square root of the dose rate. This allowed us to discuss the formation mechanism of ozone in liquid nitrogen. (author)

[en] The rates of formation and decomposition reactions of di-μ-hydroxo-bis[uranyl(VI)] ion, (UO₂)₂(OH)₂²⁺, have been measured in aqueous nitrate solutions (ionic strength = 0.5 M; M = mol dm^-3) by ¹⁷O NMR spectroscopy. In weakly acidic solutions the reactions obey the rate law: d[(UO₂)₂(OH)₂²⁺]/dt = k₂[UO₂²⁺][UO₂OH⁺] - k_-2K_a[H⁺][(UO₂)₂(OH)₂²⁺]/2, where K_a = [(UO₂)₂OH³⁺]/[H⁺][(UO₂)₂(OH)₂²⁺]. A mechanism involving a single-bridged binuclear intermediate, (UO₂)₂OH³⁺, is proposed. Rate constants (M^-1 s^-1) at 25 deg C and activation parameters ΔH^≠ (kJ mol^-1) and ΔS^≠ (J K^-1 mol^-1) for the formation and decomposition are as follows: 1.52 x 10⁵, 18.9±1.5, and -82.4±5.0 for k₂ and 2.10 x 10⁵, 23.6±1.3, and -64.0±4.2 for k_-2K_a. The rate of the decomposition reaction is compared with that in several related systems. (author)

[en] The behavior in vitreous silica of hydrogen isotopes, which had been introduced by 80-keV D⁺-ion implantation, thermal D₂ doping, or recoil tritium implantation (2.7 MeV), was studied by means of FT-IR spectroscopy, ESR spectroscopy, and radioassay with a liquid scintillation counter. The hydrogen isotopes are trapped by forming hydroxyl bonds (OD, OT). In the D⁺-ion implantation, OD bonds are formed mainly by the rupture of the ≡Si-O-Si≡ bonds. In the thermal D₂ doping, however, OD bonds are formed mainly by the isotope-exchange reaction between the preexisting OH bonds and D₂ molecules. When vitreous silica implanted by recoil tritium is heated to about 1150 K, HTO and HT are released. The OD bonds produced by D⁺ implantation decrease upon annealing at 1150 K. The OD bond-rupture is controlled by the diffusion of hydrogen isotopes trapped as OD(OT) bonds to the surface of vitreous silica. The mechanism of the diffusion of the hydrogen isotopes through vitreous silica was explained in terms of a repetition of the chemical reaction of ≡SiOD(OT) + ≡SiOSi≡ → ≡SiOSi≡ + ≡SiOD(OT). The diffusion coefficient (D_T(HTO)) of tritium according to the above mechanism was obtained as: D_T(HTO) = 2.3 x 10^-4 exp[-1.7 x 10² (kJ mol^-1)/RT] CM²S^-1. (author)

[en] Magnetic susceptibilities and electron spin resonances of Mo(V) dimers, Cs₂[Mo₂O₂S₂(ox)₂(H₂O)₂] · 2H₂O, Ba[Mo₂O₄(ox)₂(H₂O)₂] · 3H₂O, (pyH)₄[Mo₂O₂S₂(NCS)₆], (pyH)₄[Mo₂O₄(NCS)₆] · H₂O and (pyH)₄[Mo₂O₃S(NCS)₆] were observed at temperatures from 2 K to room temperature. The paramagnetic part of the magnetic susceptibilities of these compounds was small and approached zero with decreasing temperature. Under an applied magnetic field strength of 40 kOe, the susceptibilities had temperature independent regions but the spin susceptibilities derived from the electron spin resonances, observed at a magnetic flux density of about 3000 G, showed temperature dependences like antiferromagnetic dimers. This discrepancy was explained by a quasi alternating linear chain antiferromagnetic model. The corrections of the diamagnetic susceptibilities are discussed. (author)

[en] The conductance of potassium iodide was measured in water as a function of concentration (between 2 x 10^-3 and 10^-2 mol dm^-3) and temperature (between -6 and 0 deg C). The effect of temperature on the mobility of such halide ions as I^- and Cl^- ions was discussed by taking the ionic residual friction coefficient Δζ, which was defined as the overall friction coefficient subtracted by the Stokes one for slip, instead of the conventional Walden product. We compared the experimental results with the predictions due to the Hubbard-Onsager dielectric friction theory. Of the monovalent ions so far studied, the iodide ion shows the largest negative value of Δζ with the largest positive temperature coefficient; their signs are opposite to those theoretically predicted. These findings were explained in terms of the special ionic transport mechanism called the passing-through-cavities. (author)

[en] The reaction products of gaseous NbCl₅ with ammonia were NbCl₅.5NH₃ at 200 ⁰C, NbCl₅.5NH₃, Nb₄N₅, and NH₄Cl at 250-500 ⁰C, Nb₄N₅ and NH₄Cl at 550-950⁰C, delta-NbN and NH₄Cl at 1000⁰C, delta-NbN, Nb₂N, NH₄Cl, and HCl at 1100⁰C, and delta-NbN, Nb₂N, Nb₄N₃, delta'-NbN, epsilon-NbN, NH₄Cl, and HCl at 1200-1300⁰C. In the vapor-phase reaction of gaseous NbCl₅ with ammonia, the reaction of gaseous NbCl₅ with ammonia to form NbCl₅.5NH₃ occurs first. Above ca. 235⁰C, the NbCl₅.5NH₃ reacts with ammonia to form Nb₄N₅. Above ca. 1000⁰C, the Nb₄N₅ decomposes to delta-NbN. Above about 1100⁰C, in addition to these reactions, the nitriding of niobium, formed by the reduction of gaseous NbCl₅ with the hydrogen resulting from the thermal dissociation of ammonia, also occurs to form Nb₂N at 1100⁰C and Nb₂N, Nb₄N₃, delta'-NbN, and epsilon-NbN at 1200-1300⁰C. When the Nb₄N₅, formed by the vapor-phase reaction, is heated in an argon atmosphere, it changes to delta-NbN at ca. 1000⁰C, to delta-NbN and epsilon-NbN at 1100-1200⁰C, and then to Nb₄N₃ and delta-NbN at 1300⁰C. The niobium nitrides formed above 1200⁰C are uniform, ultrafine powders with particle diameters of the order of 1/100 μm. (author)

[en] Two types of lanthanoid(III) m-hydroxybenzoates, indicated in the title, have been synthesized, and the crystal and molecular structures of four representative complexes, where M = La (1), Nd (2), Sm (3), and Er (4), were determined by the single-crystal X-ray diffraction method. They are all triclinic, space group Pl-bar, and the cell constants are as follows: (1) a = 12.351(11), b = 15.533(10), c = 9.250(4) A, α = 109.86(4), β = 101.40(6), γ = 62.95(6) deg; (2) a = 12.287(4), b = 15.542(7), c = 9.194(3) A, α = 109.64(3), β = 101.46(3), γ = 62.83(3) deg; (3) a = 10.580(1), b = 12.006(5), c = 10.105(2) A, α = 111.14(2), β = 90.27(1), γ = 97.16(2) deg; (4) a = 10.586(4), b = 11.943(6), c = 10.027(5) A, α = 111.11(3), β = 90.53(4), γ = 97.26(4) deg. The final R values obtained were (1) 0.039, (2) 0.038, (3) 0.030, and (4) 0.039. The central metal atoms of both types of complexes are octa-coordinated, and each is in a squareantiprism geometry. In 1 and 2, one free acid molecule is present, and the molecule is hydrogen-bonded to the oxygen atoms of the coordinated water molecules through its carboxyl oxygen atoms. 1 and 2 have linear polymeric structure, and each pair of the metal atoms is bridged by a pair of the carboxylate ligands, while 3 and 4 have a dimeric structure, where metal atoms are bridged by two carboxylate ligands. (author)

[en] The distribution and characterization of ¹³⁷Cs in shallow water sediments are investigated. The concentration of ¹³⁷Cs in surface sediments which have been collected from the 10 - 20 m depth of Tsukumo Bay, Noto Peninsula, tends to decrease with an increase in the distance from the inner part of the bay to the outer part. Vertically, ¹³⁷Cs contents gradually decrease to the 10 cm depth and then steeply decrease beyond this depth, until at the 15 cm depth no activity is observed. A sequential extraction technique with several kinds of extractants has been employed to survey the chemical form of the nuclide in the sediments. ¹³⁷Cs is completely extracted with an ammonium nitrate solution suggesting that the nuclide is strongly adsorbed in the crystal lattice of some clay minerals and is exchangedly desorbed from the sediment phase by ammonium ions in a high concentration. A core sample has been elutriated in five components of different grain sizes, and the contents of sodium, potassium, and ¹³⁷Cs have been determined. It has been revealed that a unit amount of the finest component contains about three times as much of the nuclide as that of the coarsest one. On the contrary, the potassium contents slightly decrease with the decrease in the particulate size. (author)