Canadian Science Publishing

The initial reaction of cupric dialkyldithiophosphates and dialkyldithiocarbamates with tert-butyl hydroperoxide and α-cumyl hydroperoxide is a free radical chain process. Initiation is achieved by a redox reaction between the complex and the hydroperoxide to give alkoxy and alkylperoxy radicals. The alkoxy radicals then abstract a hydrogen from excess hydroperoxide to give alkylperoxy radicals. The cupric complexes are converted to copper sulphate by reaction with peroxy radicals while the hydroperoxide is reduced to alcohol. About 5 mol of hydroperoxide are decomposed by each mole of complex. The decomposition of tert-butyl hydroperoxide then stops whereas complete destruction of α-cumene hydroperoxide occurs by a heterogeneous ionic reaction.The kinetics of the initial reaction are second-order for both complexes. The dithiophosphate reaction is first-order in each reactant while the dithiocarbamate reaction is zero-order in the complex concentration and second-order in the hydroperoxide concentration. Simple kinetics, however, only hold for the initial rates of complex disappearance. Total dithiophosphate decomposition exhibits three stages, an initial fast reaction followed by an induction period and a rapid third stage. The concentration–time profile for dithiocarbamate decomposition is quite different and the overall rate of reaction in some instances increases as the complex concentration decreases.

A spectrophotometric study of solutions containing ferric and sulphate ions, and also ferric, sulphate, and thiocyanate ions, is reported. The measurements were made at constant temperature and ionic strength; the effect of varying acidity was also investigated. The data were interpreted with the help of the results of the first paper of this series. It is believed that the data show that FeSO₄⁺ and FeHSO₄⁺⁺ ions are formed. Values are obtained for the equilibrium constants for their formation from simple ions, and for their extinction coefficients. At higher sulphate concentrations there is evidence for the appearance of Fe(SO₄)₂⁻ and FeSO_4•HSO₄, and estimates are made of their equilibrium constants. When thiocyanate is also present, the data can best be interpreted by assuming that the complex FeSO_4•SCN is formed, and at higher sulphate probably also Fe(SO₄)₂SCN⁻⁻. Values are obtained for the equilibrium constants for the formation of these species, and the results would indicate that mixed complexes of this type are formed as readily as 'simple' ones such as Fe(SO₄)₂⁻.

Densities of water + tetrahydrofuran mixtures were measured at 5 K intervals of temperature from 288.15 to 308.15 K. Excess thermal expansion coefficients and partial molar excess thermal expansivities at 298.15 K over the whole mole fraction range were derived from the results. The significance of the expansivities is discussed in terms of the structural changes accompanying the formation of the mixture.

Tetrakis(μ-3-chloropropanoato)bis(triphenylphosphine oxide)dicopper(II) is formed by the reaction of the phosphine oxide on the parent copper carboxylate. It belongs to the triclinic space group [Formula: see text], with a = 8.603(6), b = 12.605(4), c = 12.624(5) Å, α = 76.94(3), β = 71.74(4), and γ = 74.42(4)°. The complex has the copper acetate dimer structure, in which two Cu atoms separated by 2.649(1) Å are bridged by four bidentate carboxylate groups (mean Cu—O = 1.969 Å). The Cu—O apical bond to triphenylphosphine oxide is relatively short (2.097(2) Å). The epr spectra of the solid are interpreted in terms of a dimeric species with a paramagnetic triplet state. The same signals are found in the spectra of frozen ethanol solutions, indicating that the dimer structure is retained. Magnetic susceptibility was determined in the range 81–293 K and the energy separation −2J = 328(4) cm⁻¹ was found between the two spin states. The phosphine oxide adduct is toxic to Escherichiacoli with ID₅₀ values near 100 μg/mL.

Using low-temperature ³¹P nmr, many new complexes formed between divalent cadmium (as Cd(SbF₆)₂) and monodentate phosphine chalcogenides in liquid SO₂ have been characterized. A 4:1 (L:M) complex is formed with Bu′₃PS and, possibly, Bu′₃PSe. 4:1 and 3:1 complexes are formed with Ph₃PE, (o-C₆H₄Me)Ph₂PE, (p-C₆H₄Me)₃PE, and (C₆H₁₁)₃PE (E = S or Se) as well as (o-C₆H₄Me)₂PhPSe, while 4:1, 3:1 and 2:1 complexes occur for (o-C₆H₄Me)₃PE (E = S or Se), and, probably, (o-C₆H₄Me)₂PhPS. In addition, ail the mixed ligand complexes in the series [Cd(SeP(C₆H₁₁)₃)_n(SP(C₆H₁₁)₃)_4–n]²⁺, [Cd(SeP(C₆H₁₁)₃)_n(SP(C₆H₁₁)₃)_3–n]²⁺, and [Cd(SeP(o-C₆H₄Me)₃)_n(SP(o-C₆H₄Me)₃)_3–n]²⁺ have been identified.Trends in the ³¹P nmr data are discussed.

The nature of binding in the 14 valence electron H₃AB molecules is examined, where A and B are taken from the second and third rows. The AB bonding is inferred from the computed structures, d orbital populations, and localized orbitals. Near Hartree–Fock results are reported for the strongest bonding compounds, which are those with third row atoms A, and second row atoms B. Phosphine oxide, and to a lesser extent phosphine sulfide, are found to be effectively doubly bound. Amine oxide and sulfide are found to be ionic complexes. The thiazyl bond is confirmed as triple in nature. The exotic compound F₃IC is proposed as a synthetic target.

The crystal structure of Mg₂P₂O₇ reported by Lukaszewicz has been refined by least squares analysis. Data of the hkl type with O ≤ k ≤ 6 have been used to obtain improved atomic parameters. The central oxygen atom of the P₂O₇⁻⁴ is found to have enhanced thermal motion in the plane perpendicular to the P—P vector. Thus the P—O—P bond angle appears to be linear in this phase because of a thermal averaging of the position of the central oxygen atom. This conclusion is in agreement with that obtained by Lazarev from infrared studies.

β-Zn₂P₂O₇ crystallizes in the C2/m space group with lattice parameters a = 6.61 ± 0.01 Å, b = 8.29 ± 0.01 Å, c = 4.51 ± 0.01 Å, β = 105.4° ± 0.2° and z = 2. The anion, P₂O₇⁻⁴, is centered with its mirror plane coinciding with the mirror plane of the space group. The central oxygen atom, however, shows high anisotropic thermal motion and thus it appears that the P—O—P bond angle is linear only as a result of thermal averaging. The cations are found on twofold axes in irregular sixfold coordination and these ZnO₆ groups share three edges with neighboring cations. This cation coordination is, therefore, consistent with that predicted from the red emission of β-Zn₂P₂O₇:Mn⁺⁺.

Các tập hợp cơ sở loại cơ sở Gaussian và bộ cơ sở phụ trợ đã được tối ưu hóa cho các tính toán chức năng mật độ spin địa phương. Bài báo đầu tiên này nghiên cứu về các nguyên tử từ Bo đến Neon. Các bài báo tiếp theo sẽ cung cấp danh sách các nguyên tử từ Bo đến Xenon. Các tập hợp cơ sở đã được kiểm nghiệm khả năng đưa ra các hình học cân bằng, năng lượng phân ly liên kết, năng lượng hydro hoá, và mô men lưỡng cực. Kết quả cho thấy kỹ thuật tối ưu hóa hiện tại mang đến các tập hợp cơ sở đáng tin cậy cho các tính toán phân tử. Từ khóa: Tập hợp cơ sở Gaussian, lý thuyết chức năng mật độ, Bo–Neon, hình học, năng lượng của các phản ứng.

The kinetics of the oxidation of a number of aliphatic and aromatic secondary alcohols with N-bromo succinimide has been investigated. Electron-withdrawing substituents retard the reaction considerably and electron-releasing substituents increase the rate of oxidation. The Taft ρ* value is −2.56. Cis- and trans-4-t-butyl cyclohexanols are oxidized at nearly the same rates. There is also a good correlation between the rates of the NBS oxidations and Br₂ oxidations of these alcohols. The results are interpreted in terms of a cyclic mechanism involving a rate-determining abstraction of the alpha hydrogen as a hydride anion.