Molecular structures of acetylene derivatives of tin: Part IV. Gas-phase electron-diffraction study of tetraethynyltin,Sn(CCH)4, and triethynyltin iodide,ISn(CCH)3

The geometrical parameters of tetraethynyltin and triethynyltin iodide have been determined by gas-phase electron diffraction. Triethynyltin iodide was present as an admixture in both the tetraethynyltin samples studied. Because the samples differed significantly in percentage of the iodide (17.4 ± 4.0 and 47.1 ± 3.5 mol %, in samples A and B, respectively), it was possible to determine the structures of both molecules to a sufficient degree of accuracy.The r_α, structures were solved by the least-squares treatment of the molecular intensities, using mean amplitudes and shrinkage corrections calculated from the force fields of a number of tin derivatives.The T_d-symmetry model of Sn(CCH)₄ was refined to give the following parameters: Sn-C, 2.068(5); CC, 1.228(8); CH, 1.079(51). The structural parameters for ISn(CCH)₃ (on the basis of the C_3v model with linear Sn-CC-H fragments) are as follows: Sn-I, 2.646(4); Sn-C, 2.062(17); CC, 1.226(6); ∠ISnC 108.0(2.8). (The thermal average bond distances, r_g, are given in Å, and the valence angle, rα, in degrees; the values in paren- theses are three times the standard deviations, 3σ.)The Sn-C bonds in Sn(CCH)₄, and ISn(CCH)₃ are shorter than the corresponding bonds in the monoethynyltin derivatives, Me₃SnCCH and Me₃SnCCSnMe₃. The SnI bond in ISn(CCH)₃ is noticeably shorter than those in stannane iodide and trimethylstannane iodide.     

Conformation and chiroptical properties of mandelic acids

Using CD data (solution, solid state, various temperatures), X-ray data and MO calculations for a number of substituted mandelic acids (phenylglycolic acids) an attempt was made to explain the different results for the relation between sign of the ¹L_b CD band and substitution pattern as described in the literature for various types of aromatic compounds. Moreover the reported sector rule has been reconsidered taking into account the sign and magnitude of the spectroscopic moments. It has been found that in any explanation of the signs of the ¹L_b CD bands of substituted aromatic compounds both the conformational behaviour and the spectroscopic moments should be taken into account.     

Stability constants of some bivalent first row transition metal chelates of dicarboxylic acids containing ether linkages

The stability constants of the Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+) and Zn(2+) complexes with four acids of the type HOOCCH(2)O(CH(2)CH(2)O)(n) CH(2)COOH (n = 0-3) are reported. For n = 0 the constants are in the Irving-Williams order, but not for n = 1-3.     

Anionic polymerization of 1,2-butylene oxide

Anionic polymerizations of 1,2-butylene oxide were carried out in vacuum-sealed dilatometers in the range of 30–60°C. Potassium terbutoxide and dimsyl sodium were used as initiators; dimethyl sulfoxide (DMSO) and mixtures of DMSO with tetrahydrofuran were solvents. The polymer products were analyzed by gel permeation chromatography and infrared spectroscopy. The object of the investigation was to obtain information on the mechanism of the reaction and to elucidate some of its kinetic aspects. It has been shown that the polymerizations occur by two different processes, depending on the choice of experimental conditions. One of the processes involves free ions and ion-pairs, the other, ion-pairs alone. In the first case, where dimethyl sulfoxide is used as solvent, the order of the reaction with respect to the initiator concentration far exceeds unity (～1.8), while in the second case, involving mixed solvents, the order of the reaction, for all practical purposes, is one.     

Photometrisehe Bestimmung des Anthracens und einiger seiner Abk?mmlinge

Zusammenfassung Durch Reduktion des 1,5-Dinitroanthrachinons mit Formaldehyd in warmer alkalischer Lösung und folgende Extraktion des 1,5-Diaminoanthrachinons mit Amylalkohol werden rötlich-orange gefärbte Lösungen mit einem Absorptionsmaximum bei 500 nm erhalten. Die Farbe bleibt Monate hindurch beständig. Die Reaktion ist auch zur Bestimmung von Anthracen und Anthrachinon verwendbar. Diese löst man in Mischsäure, neutralisiert und extrahiert mit Äther. Die isomeren Dinitroanthrachinone und andere sekundäre Produkte, welche entstehen könnten, beeinflussen die Linearität der Lichtabsorptionskurve als Funktion der vorhandenen Stoffmengen nicht merklich.Die Eichkurven für die Bestimmung von 1,5-Diaminoanthrachinon in amylalkoholischer Lösung bzw. die von 1,5-Dinitroanthrachinon, Anthrachinon und Anthracen, nach Umwandlung in 1,5-Diaminoanthrachinon, werden angegeben.

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Summary By reduction of 1.5-dinitroanthraquinone with formaldehyde in warm alcaline solution, followed by the extraction of 1.5-diaminoanthraquinone with amyl alcohol, reddish-orange solutions are obtained, with an absorption maximum at 500 nm. Colour remains stable for several months. The reaction is applicable also to anthracene and anthraquinone, after dissolution in sulphuric-nitric acid, neutralisation and ether extraction. Isomeric diaminoanthraquinones as well as other secondary products induce no significant changes in the linearity of light absorption.Calibration curves for the determination of 1.5-dinitroanthraquinone, anthraquinone and anthracene, after conversion to diaminoanthraquinone, are presented.

     

Application of the rotated dropping mercury electrode to the analysis of mixtures of electroactive substances

The use of poylacrylamide is recommended instead of gelatin as an ideal maximum suppressor to be employed with both the rotated dropping mercury electrode (RODE) and conventional dropping electrode (DME). It is retained at the mercury surface over the entire potential range and does not combine with heavy metals. Reproducibility of the measurement of the residual current and that of the limiting current at the RDME were studied, and it was found that accurate determinations of a single constituent (±2%) are possible at concentrations as low as 1 to 2.10^-5M. The variation of the limiting current with potential is much greater at the RDME than at the DME. This effect must be considered in the analysis of a mixture of electroactive species at the RDME. Method have been discussed for making the proper correction for a preceding wave when a limiting current of a mixture of constituents is measured. Because of its high sensitivity and good reproducibility of results, the RDME is recommended for the analysis of solutions containing one or more electroactive species at concentrations less than 10^-4M.