摘要:

AbstractThe temperature‐jump and NMR line‐broadening techniques have been used to determine the stability constants, kinetics and binding sites of nickel(II)‐purine complexes in aqueous solution. The temperature‐jump relaxation spectrum consists oftwoprocesses, dependent on concentration and pH. Previous evidence has shown that the anionic form of the ligand binds to the metal ion, hence HL, Ni2+and NiL+alone are not sufficient to explain the kinetic data. The two most likely systems consistent with the data are: (1) complexes differing in their sites of metal attachment (linkage isomers) and (2) higher order complexes, i.e. and NiL2complex in addition to the NiL+complex. Both possibilities fit the temperature‐jump data reasonably well, although neither is entirely satisfactory. The NMR experiments provide additional experimental evidence allowing a choice of mechanisms to be made. The preferred mechanism isThe rate and equilibrium constants for this scheme are calculated. From the temperature‐dependence of the NMR line width, the activation parameter for k−2and the chemical shiftΔΩNifor H(8) on theboundpurine are calculated. The results are consistent with a normal substitution mechanism for aqueous

ISSN:0021-2148    

DOI:10.1002/ijch.197300073

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe compounds Cs3FeBr5, Cs3MnBr5,Tl3FeCl5, Tl3CoCl5, (NH4)3FeCl5and (NH4)3CoCl5were prepared and their crystal structures determined. Cs3FeBr5, Cs3MnBr5, Tl3FeCl5and Tl3CoCl5belong to the tetragonal system, space group 14/mcm, isostructural with Cs3CoCl5[1]. (NH4)3FeCl5and (NH4)3CoCl5belong to the orthorhombic system, space group Pnma, isostructural with (NH4)3ZnCl5[2].

ISSN:0021-2148    

DOI:10.1002/ijch.197300074

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe theory of ideal associated solutions of the type A + B + ABjis investigated. Equations describing the chemical equilibrium, number average molecular weight, activity coefficients and excess thermodynamic functions are given. For the type of association considered, GEis always negative, HEhas the same sign as the standard enthalpy of the association reaction,ΔH°, and SEcan have positive or negative values. The excess entropy of mixing as a function of composition has a fairly complicated shape, especially in the region where the enthalpy and the free energy term compensate for each other. The extremum properties of the thermodynamic functions are at the stoichiometric mole fraction × = 1/(1 + j), and the functions have an asymmetric parabola‐like

ISSN:0021-2148    

DOI:10.1002/ijch.197300075

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe absorption spectra of aqueous bromine alone and in the presence of increasing amounts of NaCl or NaBr at acidic pH were studied. Characteristic changes in the intensity and location of certain absorption bands were observed. The spectral displacements with changes in chloride or bromide concentration indicate the formation of various complex halides. The results may provide an explanation of the changes in the sorption and oxidation processes in the interaction of aqueous bromine containing various amounts of NaCl or NaBr with cotton cellulose.

ISSN:0021-2148    

DOI:10.1002/ijch.197300076

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractSeveral fluoroanthracenes (I‐III) and fluoroanthraquinones (IV‐VII) were prepared, and their PMR and UV spectra, as well as dipole moments, recorded. These are discussed in terms of molecular‐orbital data, both of the pi‐electronic type (including nonbonding 2p‐orbitals) and of the all‐valence‐electron type. PMR signals can be assigned on the basis of such calculations. The interpretation of UV spectra is straightforward in the case of fluoroanthracenes, but other techniques are required for fluoroanthraquinones. Measured dipole moments are close to the theoretical, except in the case of 1, 4, 5, 8‐tetrafluoroanthraquinone. A distorted structure is proposed fo

ISSN:0021-2148    

DOI:10.1002/ijch.197300077

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractUV irradiation, in benzene or cyclohexane, of substitutedortho‐allylphenols to form cyclic ethers (presumably through an ionic mechanism) does not show any correlation with the pKa of the excited states of the phenols in aqueous solutio

ISSN:0021-2148    

DOI:10.1002/ijch.197300078

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of 1‐cyano‐1′‐methoxy‐azo‐iso‐propane (CMA) in decalin, N,N‐dimethylaniline (NNDA) dimethylformamide (DMF), ethylene glycol (EG), and benzonitrile (PhCN) was studied at 54.7° to 69.7°C. A rate enhancement of about four is noted in going from decalin to ethylene glycol, which is the largest solvent effect noted for azoalkane decomposition. This is also the first example of a thermolysis of an azoalkane of type R‐N;NR′ being faster than either of its symmetrical anal

ISSN:0021-2148    

DOI:10.1002/ijch.197300079

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractAttempts to introduce a fluorine atom directly at the C‐3 position of the triterpenoidal glycyrrhetic acid1by reacting the tosylate2with KF, or methyl glycyrrhetate5with Et2NCF2CHCIF, failed. The ring A olefin3and the rearrangement product4were obtained. The homoannular diene 7 was treated with NOF, but only nitroso‐fluorine compounds8, 9were isolated. Nitrosyl fluoride was also reacted with olefin3. A difluoro compound10and the expected 2‐keto‐3α‐fluoro compound11were obtained. The above two olefins were also reacted with bromine fluoride. Although the diene 7 gave only fluorine‐free compounds13, 14, the expected fluoro‐bromine compound16was obtained from3. When the 2β‐fluoro‐3α‐bromo compound was treated with Bu3SnH, the bromine atom was replaced by hydrogen and the 2β‐fl

ISSN:0021-2148    

DOI:10.1002/ijch.197300080

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractSeveralp‐vinylbenzyl malonates were synthesized and condensed with urea to form the corresponding 5‐p‐vinylbenzyl barbiturates, which were polymerized. The gross behavioral changes observed on intraperitoneal (i.p.) administration of the polybarbiturates to mice were compared with those caused by the monomers. The polymers were less toxic but had weaker sedative effects than their respective monomers, and they did not exhibit any prolongation of act

ISSN:0021-2148    

DOI:10.1002/ijch.197300081

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY