摘要:

Hexafluorodiacetonealcohol, HFDA, HOC(CF3)2CH2COCH3, is sufficiently acidic to coordinateto metal ions in an ionized form as a chelating, uninegative ligand. Complexes of Ni2 +and Cu2+ may be isolated, most conveniently by using a tridentate nitrogen-containing macrocycleas co-ligand so that five-coordinate unipositive compounds are produced.In the presence of metal ions, HFDA readily undergoes template condensation reactions withdiamino-ethane or -propane to give conplexes of ionized β-imino alcohols, e.g. -OC(CF3)2-CH2C(CH3) : N(CH2)2N : C(CH3)CH2C(CF3)20- ; these conplexes are neutral and squareplanar but become five-coordinate by solvation in, e.g., pyridine. The use of triamines H2N-(CH2),NH(CH2).NH2 (where n = 2 or 3) in template syntheses with HFDA gives complexesin which the metal ion is five-coordinate; these do not undergo solvation.

ISSN:0008-4042    

DOI:10.1139/v77-336

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

We describe the synthesis of a number of difunctional molecules in which the fluorinatedtertiary alcohol grouping, -C(CF3)20H, is combined with a nitrogen donor site such as anamino-group or a pyridine ring. In all cases, zwitterionic behaviour in solution is found resultingfrom intramolecular proton transfer from the acidic fluorinated alcohol to the nitrogen, and thissometimes persists in the solid state, e.g. NH2CH2CH2C(CF3)20H exists as the dipolar ion+NH3CH2CH2C(CF3),0-. Measurements of pK values suggest that the behaviour of thefluorinated amino-alcohols may be compared with that of the amino-acids, subject to changesto be expected from the lower acidity of the -C(CF3)20H group.Metal complexes of the fluorinated amino-alcohols form readily; specifically, neutral complexesof Co2+, Ni2+, and Cu2+ of formula M(L),, where L is an ionized amino-alcoholchelating through the ionized hydroxy group and the nitrogen atom. Measurements of formationconstants show that the six-membered chelate rings are the most stable, while a comparisonof the stabilities of fluorinated amino-alkoxy complexes with those of analogous aminoacidsshows that the former are less stable: this is attributed to the steric influence of thetrifluoromethyl groups.

ISSN:0008-4042    

DOI:10.1139/v77-337

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The syntheses of Pd(SO3F)2and Pd(SO3F)3by the reactions of palladium with BrOSO2F and S2O6F2are described. Structural information on both compounds is based on infrared, Raman, diffuse reflectance, and electronic mull spectra as well as magnetic measurements from ∼300 to ∼100 K. Palladium bisfluorosulfate is found to have a polymeric structure with the fluorosulfate group acting as a tridentate ligand. As a consequence, an octahedral environment is found for Pd2+with a3A2gground state, a µeff298value of 3.39 BM and the ligand field parameterDq = 1177 cm−1andB = 633 cm−1. Pd(SO3F)3is best regarded as PdII[PdIV(SO3F)6].

ISSN:0008-4042    

DOI:10.1139/v77-338

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Pseudo-first-order rate constants for the decarboxylation of pyrimidine-2-carboxylic acid have been determined at 65 °C in aqueous solution over the acidity range pH = 2 toH0 = −9.5. Rate constants increase rapidly from pH = 2 toH0 = −3, then remain constant. This behaviour can be accounted for by a Hammick-type mechanism in which monoprotonated pyrimidine-2-carboxylic acid loses carbon dioxide to form an ylide (stabilized by the adjacent positively charged nitrogens) which rapidly converts to pyrimidine.

ISSN:0008-4042    

DOI:10.1139/v77-339

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The MINDO/3 semi-empirical MO method has been used to study the conversion of cyclopropene to vinyl carbene. In particular, the surfaces of the ground state and the first excited singlet and triplet states have been calculated. Additional calculations, including geometry optimization, have been carried out on vinyl substituted cyclopropenes. In general, the results are consistent with the known thermal and photochemical reactivities of cyclopropenes and the results of the fewabinitiocalculations on these species.

ISSN:0008-4042    

DOI:10.1139/v77-340

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Amide indicators ionizing over the range 0–30% sulfuric acid indicate that values of theHAscale established by Yatesetal. (Can. J. Chem.42, 1957 (1964)) should be corrected by +0.33 unit.

ISSN:0008-4042    

DOI:10.1139/v77-341

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The circular dichroism spectra of Z-Val-(Ala)3-OEt in different solvents are reported. In dioxane the spectrum shows a negative band at 228–229 nm and a positive band at 212–213 nm, features which are consistent with the presence of some population of tetrapeptide molecules in a β-bend conformation. The infrared spectrum of Z-Val-(Ala)3-OEt in KBr suggests an association of the molecules in an antiparallel β-structure in the solid state.

ISSN:0008-4042    

DOI:10.1139/v77-342

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The complex solubilities of AgCl, AgBr, and AgI have been measured in several mixed solvents containing propylene carbonate and bis(trifluoroethyl)sulfite. The results indicate that a large inductive effect destabilizes the solvation of silver ions whereas the halide ions appear to be stabilized by coordination with the sulfinyl sulfur. Several physio-chemical properties of pure bis(trifluoroethyl)sulfite are reported.

ISSN:0008-4042    

DOI:10.1139/v77-343

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

New experimental evidence is given on the existence of an intramolecular hydrogen bond in β-nitroalcohols between the nitro and hydroxylic groups. The conclusion is based on examination of na → π* and infrared absorption bands and nmr spectra.

ISSN:0008-4042    

DOI:10.1139/v77-344

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Thermolyses of the azidoformate derivatives of 1,1,4a-trimethyl-trans-decalin-2β-ol, lanostanol-3β, and Δ8-lanosten-3β-ol yield the perhydro-1,3-oxazin-2-one products of nitrene insertion into the adjacent α-oriented methyl groups, as well as oxazolidinones and ketones.

ISSN:0008-4042    

DOI:10.1139/v77-345

出版商:NRC Research Press    

年代:1977

数据来源: NRC