The separation and estimation of hexa-and pentavalent molybdenum by paper chromatography

Preliminary investigations were made upon the chromatographie separation of hexa- and pentavalent molybdenum by organic solvent systems which contained potassium thiocyanate. A method for the quantitative separation of these valency states by paper chromatography in a water-acetic acid-potassium thiocyanate eluant is described. The estimations were performed colorimetrically as molybdenum pentathiocyanate which was extracted into ethyl acetate. As little as 10 μg Mo can be detected in the respective valency states. The probable error of the quantitative estimation is of the order of ± 3% for 50–100 μg Mo.     

Paper chromatography of inorganic ions part IV1

Filter paper impregnated with salts has been used for paper chromatography of inorganic cations. The RF values of a number of cations on such paper differ considerably from those on untreated paper and in some cases better separations are possible.The RF value of cations varies with the cation of the salt used for impregnation in the same manner as has been observed for “salting out” in solvent-solvent extraction.     

Enantioselektive synthese von isobutenyl-cyclobutancarbons?uren als vierring—analoga zur chrysanthemums?ure—II1

The enantiomers of 2,2-dimethyl-3-cis-(2'-methylpropenyl)-cyclobutane-1-carboxylic acids (4 and 4') and 2,2-dimethyl-3-trans-(2'-methylpropenyl)-cyclobutane-1-carboxylic acids (10 and 10') were synthesized m optically pure state. Starting from (?)-α-pinene (14) resp. (+)-α-pinene (14') 2,2-dimethyl-3-cis-formyl-cyclobutane-1-car-boxylic acid methylester (21 and 21') was received in an enantioselective pathway and isomerised by acid-catalysisto 2,2-dimethyl-3-trans-formyl-cyclobutane-1-carboxylic acid methylester (23 and 23'). In a following Wittig-reaction the 4 aldehyde-esters 21, 21', 23 and 23' were converted to the enantiomers of isobutenyl-cyclobutane-carboxylic acid methylesters and esterified by m-phenoxibencylic alcohol resp. hydrolysed to isobutenyl-cyclo-butane-carboxylic acids.     

Relative olefin—metal bond strengths in some platinum (0) compounds. Part II1

Measurements are reported for the enthalpies of solution of:

where L is triphenylphosphine and the olefins used were cis- and trans-1,2-diphenyl-ethene. These enthalpies, when combined with other data, lead to the conclusion that the difference in the relative strengths of the platinum—olefin bonds (trans-1,2- diphenylethene&>;cis-1,2-diphenylethene&>;phenylethene) found previously arises mainly from electronic rather than from steric effects of the olefins in the complexes.     

Analysis of peroxides separation and identification by paper chromatography

The paper chromatography of hydrogen peroxide and numerous organic peroxides (mainly aliplhatic) has been investigated under various conditions. By the use of several stationary and moving phases nearly the peroxides may be separatcd and identified in very small amounts.     

Photochemical studies on bicyclic βγ-unsaturated ketones: II1. Okadi-π-methane rearrangements originating from some state other than T1 (π-π*)

the unquenchable ODPM reaction observed on direct irradiation of three βγ-unsaturated ketones has been studied in solution and in the vapour-phase. The results suggest that the higher triplet state might be the origin of this reaction. Thermal generation of this excited state in one case supports the conclusion. The vapour-phase results further suggest the existence of both diradical and concerted pathways for the [1,3]-acyl shift from the excited singlet state, and the possibility of a similar pattern from the higher triplet state.     

Determination of molybdenum at μ l−1 levels by catalytic spectrophotometric flow injection analysis

A flow injection analytical method based on the catalytic action of molybdenum on the oxidation of iodide by hydrogen peroxide in acidic medium is proposed. The triiodide formed is measured spectrophotometrically at 350 nm. Molybdenum is determined in natural water samples without preconcentration at a sampling rate of 90 h^?1 with 200-μl sample injections. The detection limit is 0.7 μ l^?1 and the calibration curve is linear over the range 1–1000 μ l^?1. The relative standard deviation is 0.83% for 50 μ l^?1 molybdenum and 1.9% for 13 μ l^?1 molybdenum.     

EPR evidence for 17O− on molybdenum oxide supported by silica-gel

The EPR spectrum of ¹⁷O^? on partially reduced molybdenum oxide supported on silica-gel has been observed following adsorption of N₂O at room temperature. The spectrum is chracterized by g_⊥=2.019 and g_|=2.002 with a_|¹⁷O^?=96±1 G and a_|⁹⁵MO,⁹⁷MO=7.5±0.5 G. The O ^?ion appears to undergo exchange with oxide ions at the surface.     

BF分子X1∑+,A1∏和B1∑+电子态的势能函数

使用SAC/SAC-CI和D95++,6-311++g,6-311++g**及D95(d)基组,分别对BF分子的基态X1∑+、第一简并激发态A1∏和第二激发态B1∑+的平衡结构和谐振频率进行优化计算.对所有计算结果进行比较,得出6-311++g**基组为最优基组.运用6-311++g**基组和SAC方法对基态X1∑+,SAC-CI方法对激发态A1∏和B1∑+进行单点能扫描计算,并用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由得到的势能函数计算了与X1∑+,A1∏和B1∑+态相对应的光谱常数,结果与实验数据较为一致.     

Kinetic energy dependence of the reactions of N+ and N2+ with molybdenum

Mass-selected beams of N⁺ and N₂⁺ in the energy range 5–50 eV react with molybdenum to produce a surface nitride. The relative reaction cross section for N⁺ reaction is higher than that of N₂⁺ in the range 5–25 eV and N₂⁺ exhibits a reaction threshold near 7 eV. The N₂⁺ threshold suggests collisional dissociation prior to reaction.     

The separation of hyponitrite from nitrite,nitrate and hydroxylamine by paper chromatography

The preparation of carbonate-free sodium hyponitrite and the resolution by paper chromatography of mixtures of sodium hyponitrite with sodium nitrite, nitrate, or hydroxylamine are described. Observations were made upon an uncharacterized impurity which was present in very small amounts in the prepared sodium hyponitrite samples.     

Rotational analysis of the a3Π0+,1-X1Σ+ emission systems of GeH+

New emission systems have been observed from the helium afterglow reaction of GeH₄ in the 520–610 nm region. On the basis of the rotational analysis, they were assigned to the a ³Π_0⁺-X¹Σ⁺ and a³Π₁-X¹Σ⁺ subsystems of GeH⁺. Spectroscopic constants have been determined for the GeH⁺ (a³Π_0⁺, a³Π₁, X¹Σ⁺) states.     

Asymmetrical nitrogen-40;1 Geminal systems-261 N-chlorohydrazines3

The factors determining the kinetic and thermodynamic stabilities of N-chlorohydrazines are discussed. Acyclic N-chlorohydrazines exist only as trialkyldiazenium chlorides 3a,b. Chlorination of 2-acyl-1, 1-dimethylhydrazines 6a,b gave 1,4-diacyl-2,3-dimethylhexahydro-1,2,4,5-tetrazines 7a,b via hydrazyl radical intermediates, and chlorination of a 1-phenylpyrazolidin-5-one 8 gave phenylazoisovaleric esters 9a,b. Stable N-chlorohydrazines were obtained from bicyclic hydrazines; viz. the 2-chloro-1,2-diazabicyclo [2.2.2]octan-3-one 12 and 7-chloro-1,7-diazabicyclo[2.2.1]heptane 16. The restricted inversion of N(7) in 16 and its 1-methyl quaternary salt 21 were observed in the ¹³C-NMR spectra. The acyclic N-chloro-hydrazinium salt 25 was isolated.     

Potential energy curve of 1Σ+ Li+/He

The potential energy curve of the system Li⁺/He has been determined with moderately large basis sets for 0.5 ? r ? 10.0 a₀ both at the SCF level and including correlation. The present SCF results predict a deeper well (?0.00248 au) at a smaller r(3.66 a₀) compared with earlier calculations. Correlation deepens the well further (?0.00274 au), but pulls it inward slightly (3.63 a₀). In the repulsive part the calculated curve lies above the experimental one, especially at shorter distances. A similar behavior has been noted in the systems Li⁺/H₂, Li⁺/CO and Li⁺/N₂, suggesting that the experimental determinations may underestimate the interaction in this region by 10–20%.     

The pair polarizabilities of Li+/Li+ and Cl−/Cl−

Ab initio SCF MO energies and pair polarizabilities are reported for the pairs Li⁺/Li⁺ and Cl^?/Cl^? over the ranges of internuclear separation which are of importance in molten LiCl. The shapes of the β(R) curves resemble those of inert gas diatoms. The Cl^?/Cl^? interaction is predicted to make a rather small contribution to those properties of molten LiCl which depend on $\text{α}$⁽²⁾(R), and a larger contribution to properties which depend on β(R). The Li⁺/Li⁺ interaction contributes almost nothing to the bulk polarizability.     

BF分子X1Σ＋, A1P和B1Σ＋态的势能函数

使用SAC/SAC-CI和D95＋＋, 6-311＋＋g, 6-311＋＋g**及D95(d)基组, 分别对BF分子的基态X¹Σ^＋、第一简并激发态A¹Π和第二激发态B¹Σ^＋的平衡结构和谐振频率进行优化计算. 对所有计算结果进行比较, 得出6-311＋＋g**基组为最优基组. 运用6-311＋＋g**基组和SAC方法对基态X¹Σ^＋, SAC-CI方法对激发态A¹Π和B¹Σ^＋进行单点能扫描计算, 并用正规方程组拟合Murrell-Sorbie函数, 得到相应电子态的势能函数解析式, 由得到的势能函数计算了与X¹Σ^＋, A¹Π和B¹Σ^＋态相对应的光谱常数, 结果与实验数据较为一致.