摘要:

Proton magnetic resonance spectra of some complexes of In, Zn, Cd, and Sn halides and perchlorates with N,N-dimethylacetamide (DMA) have been measured in acetone-d6. Low field shifts of the methyl resonances of DMA on complex formation are dependent on metal and anion. The similarity of the spectra of all the complexes suggests only oxygen-coordinated DMA in solution. Infrared spectra in the range 2 000–625 cm−1are recorded. Changes in the C—O and C—N stretching frequencies of the ligand on coordination are consistent with oxygen-bonded DMA both in the solid complexes and in solution.The new compounds Zn(ClO4)2•6DMA, Cd(ClO4)2•6DMA, CdI2•2DMA, and SnCl4•2DMA are reported.

ISSN:0008-4042    

DOI:10.1139/v66-284

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Kinetic deuterium and carbon-13 isotope effects are calculated for the SN2 exchange reaction of CH3I with *I−(131) and for the CH3I solvolysis in water. The normal vibrational frequencies of CH3I and of the transition state(X = I or OH2) are evaluated from force constants by solving the secular equation with an IBM 7094 computer. Values for force constants of the planar CH3moiety (with an sp2C atom) in the transition state are obtained by comparison with suitable stable molecules. For the iodide exchange reaction, there is not much dependence of the calculated D isotope effect on the particular choice of ƒCIand ƒ12(interaction between CI stretches) if these force constants are within reasonable limits. The bending force constantƒHCI(≠) may then be adj usted to reproduce the experimental D isotope effect.Based on the simple transition state modelit is not possible to obtain agreement with the experimental D effect in the solvolysis reaction without assuming an extremely high value of ƒHCI. If must be concluded that a water molecule is probably involved in the transition state. On the basis of the modelthe experimental D effect may be reproduced with a suitable choice of ƒHCIand ƒHCO. It is shown that, under favorable circumstances, experimental temperature dependence data may be applied for a distinction between different sets of, ƒCH, ƒHCH, and ƒHCI(or ƒHCO) which reproduce the experimental isotope effect at one temperature.

ISSN:0008-4042    

DOI:10.1139/v66-285

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Linear relationships exist between the logarithms of equilibrium quotients, [SH+]/[S][H+], of diverse bases as they vary with acid concentration in moderately concentrated mineral acids. For purposes of formulating these linear free energy relationships in standard form, the equilibrium quotient for protonation of a hypothetical aromatic primary amine of pKazero has been chosen as horizontal coordinate; this is given by (−H0 − log [H+]). Log ([SH+]/[S]) + H0is plotted against (H0 + log [H+]). The slope,of the linear plot is a parameter which characterizes the response of the equilibrium quotient to changing acid concentration. The intercept represents the thermodynamic pKaof the base. This constitutes a general method for estimating the pKaof any base which undergoes protonation in moderately concentrated mineral acid, with reference to the single acidity function,H0. For bases of diverse type, pK's estimated by this method are in good agreement with those estimated by the acidity function method. Use of the new correlation procedure as a check on the validity of several acidity functions and its application to equilibria not involving proton gain or loss are also discussed.

ISSN:0008-4042    

DOI:10.1139/v66-286

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Linear relationships exist between logkψ + H0(for reactions of weakly basic substrates) or logkψ(for reactions of strongly basic substrates) and(H0 + log [H+]). These are linear free energy relationships. For weakly basic substrates, the correlations obtained are better than in plots of (logkψ, + H0) versus logor of logkψversus −H0. The slopes in plots of logkψor (logkψ + H0), as appropriate, against (H0 + log [H+]) are taken as parameter,, which characterizes the response of the reaction rate to changing mineral acid concentration. Values offor reactions of strongly basic substrates reflect only relationships between protonated substrate and transition state, and may be related to reaction mechanism.values for reactions of weakly basic substrates reflect both equilibrium protonation of the substrate and transformation of protonated substrate to transition state, and are therefore less directly related to mechanism. However, thevalues for the two steps are additive and that for the latter step can be obtained by subtraction if the overallvalue and that for equilibrium protonation are known.

ISSN:0008-4042    

DOI:10.1139/v66-287

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The well-known similarities of the simple Huckel and omega technique molecular orbital procedures for pi electrons to Pople's self-consistent field method are extended by considering systematic approximations to the latter. From the relationships found, Huckel-method Coulomb integrals and omega values for a variety of atoms (Be, B, C, N, O, F, Mg, Al, Si, P, S, Cl, Ge, As, Se, Sn, Sb, Te) are derived. The Huckel and omega Coulomb integrals are shown to be directly related to a recent definition of orbital electronegativity. The ability of the omega techniques to improve upon the Huckel-method charge distributions is discussed by use of an arbitrary but typical example.

ISSN:0008-4042    

DOI:10.1139/v66-288

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Diffuse reflectance spectroscopy can be used for the analysis of multicomponent systems in the adsorbed state. The Kubelka–Munk theory for diffuse reflection and transmission on light-scattering layers has been applied for this analysis. Simple dye mixtures adsorbed on thin-layer chromatography-grade adsorbents were employed. The method can be adapted directly to the analysis of incompletely separated components on chromatographic adsorbents.

ISSN:0008-4042    

DOI:10.1139/v66-289

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Single crystals of potassium sulfamate, KNH2SO3, enriched in the isotope15N, were irradiated, and examined at 77° K by electron spin resonance. Two intermediates, neither of which are present on examination at 300 °K, have been identified as NH2and NH2SO3. A possible radiolysis mechanism is discussed.

ISSN:0008-4042    

DOI:10.1139/v66-290

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The radicals N2H4+and PF2have been detected by electron spin resonance in -γ-irradiated NH4PF6. The radical N2H4+was shown to be formed from NH3+radicals detectable after low-temperature irradiation.

ISSN:0008-4042    

DOI:10.1139/v66-291

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Ultraviolet, infrared, and Raman spectra were measured for acetic acid and propionic acid in sulfuric acid solutions of various acidities. Infrared spectra of acetic acid and benzoic acid were measured in deuterosulfuric acid and aqueous deuterated sodium hydroxide solutions. From the detailed analyses of the ultraviolet absorption change the pKBH+values of acetic and propionic acids were found to be −6.12 and −6.33, respectively. In the infrared and Raman spectra of the protonated acids, the C=O stretching band at about 1700 cm−1disappeared and a new strong infrared absorption band appeared at about 1600 cm−1. The frequency of the latter band, which can be assigned to antisymmetric C—O stretching band, is very similar to that of the carboxylate group. The acidity dependence of these infrared spectra was parallel with that of the ultraviolet absorption. These facts confirm that the protonated carboxyl group has a skeleton [—C(OH)2]+similar to the carboxylate group [—CO2]−.

ISSN:0008-4042    

DOI:10.1139/v66-292

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Total cross sections for ionization by 75 V electrons have been measured for a wide range of molecules. On the whole the results are in agreement with the cross sections reported by Lampeetal. rather than those reported by Otvos and Stevenson. The results fit neither a single linear correlation with molecular polarizability nor a simple postulate of additivity of atomic ionization cross sections.

ISSN:0008-4042    

DOI:10.1139/v66-293

出版商:NRC Research Press    

年代:1966

数据来源: NRC