摘要:

Dodecamethylcyclohexaphosphazene N6P6Me12,1, forms 1:1 complexes with palladium(II) chloride,2, and platinum(II) chloride,3. Their31P,1H, and13C nmr spectra show them to be rigid molecules in solution, with an approximate plane of symmetry. Crystals of2are orthorhombic,a = 17.4030(3),b = 15.4897(5),c = 10.7417(2) Å,Z = 4, space groupP21212. The structure was determined from diffractometer X-ray data and refined by full-matrix least-squares methods toR = 0.031 for 3545 reflections with I ≥ 3σ(I). The metal atom has square planar coordination, and forms 6- and 10-membered chelate rings with the phosphazene ligand. The mean P—N bond length is 1.609 Å; the variation of bond lengths within the ring is consistent with model calculations of changes in bond order arising from the localization of bonding electrons.

ISSN:0008-4042    

DOI:10.1139/v81-350

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Hexadecamethylcyclooctaphosphazene N8P8Me16,1, forms a 1:1 complex,2, with cobalt(II) nitrate. Crystals of2are triclinic,a = 10.891(2),b = 11.201(2),c = 14.944(2) Å, α = 93.21(1), β = 95.66(1), γ = 104.69(1)°,Z = 2, space group. The crystal structure was solved by direct methods and was refined by full-matrix least-squares procedures toR = 0.037 andRw = 0.047 for 5165 reflections with I ≥ 3σ(I). All the hydrogen atoms were found. The structure consists of a cation [N8P8Me16CoNO3]+and a free nitrate anion. The cobalt atom is coordinated by an unsymmetrical bidentate nitrate ion and by four nitrogen atoms of the phosphazene ring. The metal is attached near one end of the ring, forming six-, ten-, and two four-membered chelate rings, and induces bond length variations which are independent of local conformation and which arise from the localization of bonding electrons.

ISSN:0008-4042    

DOI:10.1139/v81-351

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Vibrational spectra for 2,2′-diphenyldicarboximide have been determined and allow for a valence force field calculation. Bond orders obtained in this way have been compared with a population analysis and to the bicentric electronic energies determined by a CNDO/2 calculation, thus providing a twofold approach to the electron delocalization in 2,2′-diphehyldicarboxamide. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v81-355

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Site selective fluorescence spectroscopy of a crystal of europium gallium garnet containing Cr3+as an impurity has been carried out. An analysis of the experimental results reveals that the strongest fluorescence spectrum between 590.0 nm and 620.0 nm is due to emission from an Eu3+−Cr3+pair. Fluorescences of farther removed pairs and that of Eu3+occupying the 8-coordinateddsite and 6-coordinated Ga3+site are also assigned. Energy transfer between the various sites occurs while the excitation spectra for the R lines of Cr3+show that extremely fast transfer takes place between the R2and R1levels.

ISSN:0008-4042    

DOI:10.1139/v81-352

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The results of dye–dye interactions for the pairs, acridine orange – methylene blue, acridine orange – phenosafranine, and acridine orange – disulphine blue have been presented. It has been found that at comparable concentrations the interaction is rather weak, and the formation of mixed entities is only possible at relatively high proportions of one of the components. However, the evidence of mixed dimers in the form of a new absorption band is lacking. Phenosafranine remarkably promotes dimerization of acridine orange. An experimental demonstration of the dimer spectra of acridine orange has thus been possible. The interaction of the anionic dye disulphine blue with cationic acridine orange has been observed to be the weakest of all the pairs, indicating the vital role of the structural parity for interaction. At comparable low concentrations, none of the dye-pairs studied have revealed compound metachromasy in the presence of a polyelectrolyte, suggesting unfavorable mixed dye aggregation under ordinary conditions.

ISSN:0008-4042    

DOI:10.1139/v81-353

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Ab initiomolecular orbital calculations have been carried out for the series of succinic, maleic, and phthalic anhydrides unsymmetrically substituted with CH3, CH3O, Cl, F, and CN. The size of the LUMO coefficient on the carbon atom of the carbonyl group provides a reliable guide to the relative reactivities of the two carbonyl functions. The predictions based on the intrinsic reactivities are in good agreement with the regioselectivities observed in metal hydride reductions of succinic anhydrides. In the series of maleic and phthalic anhydrides the above considerations are applicable only to methyl derivatives. The compounds substituted with lone pairs-bearing groups (OCH3, Cl, F) form stable chelates with the cations present in the reaction media. Since the chelated carbonyl group is strongly activated toward the nucleophilic addition, the "bridging" effect is the dominant factor controlling orientation of hydride addition. The optimum position for the nucleophilic attack in cyclic anhydrides was calculated. The results confirm the generality of the nonperpendicular, restricted path of nucleophilic attack on the carbonyl group in succinic anhydride.

ISSN:0008-4042    

DOI:10.1139/v81-354

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Reaction of 1,3,5-trinitrobenzene with potassium 2,4,6-trimethylphenoxide in dimethyl sulfoxide solution leads to σ-complex formation concurrently with displacement of a nitro group. The results provide definitive evidence for σ-complex formation via the oxygen of aryloxide ion in this system, and contrast with the situation that obtains with phenoxide ion itself, which under corresponding conditions yields the carbon-bonded σ-complex as the product of thermodynamic control. Stereoelectronic factors in σ -complex formation and in the diaryl ether resulting from nitro displacement are also discussed.

ISSN:0008-4042    

DOI:10.1139/v81-356

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Bis(acetylacetonato) copper(II) catalysed thermal decomposition of benzoylphenyldiazomethane (1) leads to the insertion of benzoylphenylcarbene into the N—H bond of amines; the insertion products undergo facile air oxidation giving rise to ketoimines. The uncatalysed thermal decomposition of benzoylphenyldiazomethane yields the corresponding diphenylacetamide derivatives of amines.

ISSN:0008-4042    

DOI:10.1139/v81-357

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

(±)-Nα-Methyl-Nβ-acetylphlegmarine has been synthesized in a manner that defines the relative configuration at four of the five chiral centres of the molecule. Five isomers of the title compound have also been prepared and characterized.

ISSN:0008-4042    

DOI:10.1139/v81-358

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The study of acid–base reactions in oxydipropionitrile (ODPN) by means of glass and hydrogen electrodes allows us to determine the pKA's of several acid–base pairs. Use of Strehlow's hypothesis leads to a correlation of acidity scales in water, acetonitrile and oxydipropionitrile. Because of solvent degradation in highly alkaline solution it proved impossible to determine the ionic product of the medium and consequently the pKB's of several acid–base pairs. The weak basicity of ODPN allows for the easy titration of very weak bases such as urea, DMSO, and HMPT in water. For weak acid the importance of homoconjugation is clearly shown leading to the weak ability of the medium to solvate both anions and protons. Some homoconjugation constants have been determined by the analysis of the potentiometric titration curves. Finally a study of the quinone–hydroquinone couple shows that this is also a pH indicator in ODPN. At the present time our studies provide a pKscale of practical use over 20 units. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v81-359

出版商:NRC Research Press    

年代:1981

数据来源: NRC