Journal of Inorganic and Nuclear Chemistry最新文献

Using a 366 nm source, irradiation of a CH₂Cl₂ solution of M₂(CO)₁₀ (MMn, Re) and an excess of (LL):a 1:1 mixture of R_IR_IINC(Se)Se(Se)CNR_IR_II and R_IR_IINC(Se)Se₃(Se)CNR_IR_II [if R_I R_II C₂H₅(LL) (Et₂dsc-dscEt₂), if R_IR_IIN = morpholyl (LL) = (modsc-dscmo), if R_ICH₃, R_IIC₆H₅ (LL) = (Mephdsc-dscMeph) quantitatively produces [M(CO)₄L], where $\text{L = R}{}_{\mathrm{I}}\text{R}{}_{\mathrm{II}}\text{NC}\textcolor{red}{}\text{(−)}$ The photochemical reaction is extensively studied, the quantum yields and the rate constants are determined. A S_N1-type mechanism is proposed, involving homolytic MM bond fission as the rate determining step.

The electronic spectrum of Cu(II) doped in a Zn(dtc)₂ matrix (dtc-diethyldithiocarbamate anion) has been studied theoretically using the angular overlap model (AOM) and crystal field theory (CFT). The effect of the ligand bite angle (α), polar angle (θ) and spin-orbit coupling on the electronic spectrum has been traced. The contributions of these factors have been found to be small, yet important in producing the transition energies and polarizations of the observed spectrum. Spectral AOM parameters, derived from the analysis of the charge transfer bands have been used to interpret the photoelectron spectra and the $\text{“d-d”}$ transitions. Two sets of CFT parameters (called σ- and π-sets) were needed in the CFT treatment to reproduce the AOM treatment and this explains why previous CFT treatments were unsuccessful.

Crystallographic data for the full series of rare earth decavanadates of the type Ln₂V₁₀O₂₈·nH₂O have been obtained from monocrystals by precession and Weissenberg measurements. The substances belongs to four different structural groups and their characteristics are briefly discussed. The vibrational spectra of the compounds have also been recorded and interpreted.

The possible existence of a monovalent ion of mendelevium has been examined further by radiopolarography. Experiments were conducted in several aqueous media with ²⁴¹Am, ²⁴⁹Cf, ²⁵⁴Es, ^255,256Fm and ²⁵⁶Md tracers. Half-wave amalgamation potentials of Md in tetramethylammonium perchlorate and in LiCl were identical within the experimental errors at −1.755 ± 0.005 V vs the saturated calomel electrode, in good agreement with an earlier study by radiocoulometry in an ammonium acetate medium. No shift in the half-wave potential of Md was observed due to NH₄⁺ or Cl⁻ ions; hence, these ions do not act as complexing agents for Md ions present during electrochemical reductions. The shift in the half-wave potential observed in the presence of citrate as a complexing agent was characteristic of the reduction process Md²⁺ → Md⁰(Hg). In noncomplexing media, the slope of the logarithmically transformed wave of Md was ∼ 30 mV, consistent only with a reversible, two-electron reduction process. All of our results provide evidence for electrochemical reduction of the Md²⁺ ion only and disprove the existence of an the intermediate Md⁺ ion in aqueous solution with properties like those of Cs⁺, Ag⁺ or Cu⁺.

Cu(II) complexes were prepared with the following acids: propionic, α- and β-bromoproionic, α- and β-chloropropionic, α,β-dichloropropionic and β-iodopropionic. On the basis of elemental and thermogravimetric analyses the compositions of the complexes crystallized from water and recrystallized from methanol, acetone and dioxane was determined.

The effect of these solvents on the spectral properties of Cu(II) halopropionates in the UV and IR region was investigated, and it is shown that in solvents of low dielectric constants dimeric structures may occur. IR spectra of the Cu(II) complexes recrystallized form the above mentioned solvents and of their sodium salts were measured. The results obtained indicate that the structure of Cu(II) halopropionates is always dimeric in the solid state, analogous to that of Cu(II) acetate monohydrate. This conclusion is also confirmed by abnormal magnetic moments of these complexes. Temperature dependent magnetic susceptibilities indicative of antiferromagnetic nature were observed.

Carbons possessing unique properties somewhat like those of glassy carbon have been prepared from structural microcrystalline cellulose precursors by prolonged pyrolysis up to 800°C in a nitrogen atmosphere. Samples of the dry microcrystalline cellulose powders were fabricated into various shapes in a high pressure mold or by slow drying of an aqueous suspensoid gel in a mold under ambient conditions. Pyrolysis gave objects of amorphous carbon about one-third the original size. Some of the carbons are about as hard as glass and have a density (helium pycnometer) of 2.01 g/cm³ (cf. graphite 2.265). As expected, the carbon resulting from the pressed microcrystalline cellulose dry powders had a lower density and more pores than carbons produced from structural forms, prepared from air dried, aqueous gels. Pore size and pore size distribution data and scanning electron photomicrographs are shown.