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A. K. Gupta J. C. Maire R. R. Gupta U. S. Mahnot B. P. Bachlas A. Baldy 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):735-747
The rawpH-data, obtained from the potentiometric titrations of the titled ligands with NaOH in 75% (v/v) dioxane-water mixture performed at 20, 30 and 40°C at constant ionic strength (=0.1M-NaClO4), have been adequately corrected for dilution, and solvent effects in order to evaluate thermodynamic dissociation constants. Variance of the latter as a function of temperature has also been accounted for. The differing magnitudes of thermodynamic dissociation constants of the titled ligands have been explained on the basis of the non coplanar orientation of the phenyl ring in the ligands and a comparison has been made with those of unsubstituted benzoylacetone, dibenzoylmethane and acetylacetone.Following similar technique, thermodynamic stepwise and overall formation constants of the titled metal-ligand systems have been obtained and the results correlated with ligand basicity inverse metal crystal radii and second potentials of metals. Decrease in the free enthalpy (–G) of complexation reaction has also been evaluated.
Untersuchung der Gleichgewichte von Mn(II), Mg(II), Ca(II), Sr(II) und Ba(II) mit p-Fluor-, p.-Chlor-, p-Brom-, p-Methyl-benzoylaceton und 1-(4-Fluorphenyl)-1,3-pentanedion
Zusammenfassung Aus der potenitometrischen Titration der Titelverbindungen mit NaOH in 75 (v/v) Dioxan—Wasser bei, 20, 30 und 40°C bei konstanter Ionenstärke (=0,1M-NaClO4) wurden die thermodynamischen Dissoziationskonstanten ermittelt. Verdünnungs-, Lösungsmittel-und Temperatureffekte wurden berücksichtigt. Die unterschiedlichen Dissoziationskonstanten werden mit der Nichtplanarität des Phenylrings in den Liganden erklärt. Außerdem wurden die Komplexbildungskonstanten bestimmt; sie sind in die Diskussion miteinbezogen.相似文献
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The properties of the negative parity states of55Fe and57Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states. 相似文献
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Thirty triorganotin(IV) derivatives of the type R3Sn(R′COCHCOCH2COR″) and [R3Sn]2 (R′COCHCOCHCOR″) (where R = CH3, C2H5, nC3H7, nC4H9 and C6H5 and R′ = R″ = CH3, C6H5 or R′ = C6H5, R″ = CH3) have been synthesised by the interaction of R3SnCl with mono- or disodium salt of 2, 4, 6-heptanetrione, 1-phenyl-1, 3, 5-hexanetrione and 1, 5-diphenyl-1, 3, 5-pentanetrione in 1:1 and 2:1 molar ratios, respectively. The complexes have been examined by their molecular weight, IR, PMR and elemental analyses and their tentative structures assigned. Both “Z” and “E” forms have been identified in the 1:1 complexes in equilibrium with the enol form containing five coordinate tin. The 2:1 derivatives contain one five- and other four coordinated tin(IV) except the phenyl analogue where both the tins are five coordinated. 相似文献
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The effect of the radiative cooling of electrons on the gravitational collapse of cold dust grains with fluctuating electric
charge is investigated. We find that the radiative cooling as well as the charge fluctuations, both, enhance the growth rate
of the Jeans instability. However, the Jeans length, which is zero for cold grains and nonradiative plasma, becomes finite
in the presence of radiative cooling of electrons and is further enhanced due to charge fluctuations of grains resulting in
an increased threshold of the spatial scale for the Jeans instability. 相似文献
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The LSD (Logic for Structure Determination) program gener-ates organic molecular structures from 1D and 2D NMR data without resorting to chemical shift databases. Its use in the res-olution of natural product structure determination problems has been already reported in the literature. This paper describes how data and structures are internally represented and pro-cessed by LSD to build solution structures. 相似文献
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The thermodynamic formation constants of N-(alkyl)-2- and/or 3-mercaptoacetamides complexes with dimethyl-, diethyl-, and n-dibutyltin(IV) cations have been determined potentiometrically in a dioxane-water mixture (75% v/v) at 30 ± 0.1°C in μ = 0.1 M NaCl using the Irving-Rossotti method and refined by the least-squares method. The basicity of the ligands follows the order C2H5NHCOCH2SH > n-C3H7NHCOCH2SH > n-C4HgNHCOCH2SH > C2H5NHCOCH2CH2SH > n-C3H7NHCOCH2CH2SH > n-C4Hg- NHCOCH CH SH. For each ligand the stability order of dialkytin(IV) complexes decreases as follows: [Me2Sn(IV)]2+ >[Et Sn(IV)]2+ > [n-Bu2Sn(IV)]2+. This order is consistent with the group electronegativities of [R2Sn(IV)]2+ cations calculated from Sanderson's electronegativity scale. 相似文献