摘要:

The crystal structure oftrans-[Pt(DMF)(2,6-lutidine)Cl2] has been determined by X-ray diffraction. The crystals are orthorhombic, space groupPbca, witha = 11.612(13),b = 26.504(33),c = 9.271(9) Å, andZ = 8. The structure was refined by full matrix least-squares analysis to a conventionalRfactor of 0.051 and a weightedRw = 0.044. The coordination around the platinum atom is square planar. The 2,6-lutidine ring is perpendicular to the platinum plane. DMF is bonded to platinum through the oxygen atom. It is planar and makes an angle of 71 ° with the platinum plane. Thecis–transconfiguration of the [Pt(DMF)(L)Cl2] (L = pyridine derivative) complexes in DMF solution is discussed.

ISSN:0008-4042    

DOI:10.1139/v80-016

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The carbon-13 relaxation time data for several norbornane and adamantane derivatives are presented. It is shown that the most probable principal axis of the rotational diffusion tensor is an axis which contains the centre of mass of the molecule and the heterosubstituent. The influence of the C—Ĉ—H bond angle on the calculation of methyl group rotation barriers from relaxation time data and on the barrier is discussed

ISSN:0008-4042    

DOI:10.1139/v80-017

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Nematic lyotropic liquid crystalline materials, which spontaneously align in a magnetic field (Type II) have been prepared from a mixed detergent system consisting of potassium dodecanoate and decyltrimethylammonium bromide. This system has an advantage that the charge on the interface of the finite disc micelles can be readily varied. Sodium and bromide ion interactions with the interface have been investigated by nuclear magnetic resonance of the ions. Deuterium magnetic resonance spectra of deuteriated water and specifically deuteriated detergent chains have been obtained. The results show that there is a water structure built around the carboxylate headgroups which ceases to be stable when about 30% of potassium dodecanoate is replaced by decyltrimethylammonium bromide. Bromine magnetic resonance studies show that the bromide ion interacts only weakly with carboxylate but indicates, as would be expected, much stronger interaction with the trimethylammonium groups. The sodium ion in contrast was found to bind strongly with carboxylate and weakly with trimethylammonium. The sodium spectra indicate that the association of sodium with carboxylate is complex, involving two specific binding sites. Deuterium spectra from deuteriated hydrocarbon chains are interpreted in terms of the motional freedom of the individual chains. The results re-emphasize that the motional properties of a particular hydrocarbon chain of an amphiphile in the micellar bilayer is determined to a large extent by its headgroup and that the behaviour of one chemical species cannot be inferred from that of another.

ISSN:0008-4042    

DOI:10.1139/v80-018

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Rates of hydrolysis of 1-ethoxy-3,3,5,5-tetramethylcyclopentene and 1-methoxy-2,3,3,5,5-pentamethylcyclopentene measured in mineral acid and formic and acetic acid buffer solutions show general acid catalysis and give large kinetic isotope effects in the normal direction (kH/kD > 1). This indicates that these reactions proceed by the conventional mechanism for vinyl ether hydrolysis in which proton transfer from the catalyzing acid to the substrate is rate-determining, and that the I-strain in these substrates is insufficiently great to shift the reaction mechanism to rapidly reversible substrate protonation followed by rate-determining hydration of the ensuing cationic intermediate.

ISSN:0008-4042    

DOI:10.1139/v80-019

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Reaction of pyridinecarboxaldehydes1with α-ethoxyvinyllithium2affords 2-ethoxy-1-(pyridinyl)-2-propen-1-ols3which on hydrolysis with aqueous formic acid give pyridinyl α-hydroxyketones4. Selenium dioxide oxidation of4aand4bprovides pyridinyl α-diketones9which on condensation witho-phenylenediamine afford 3-methyl-2-(pyridinyl) quinoxalines11. Pyridinyl α-hydroxyketones4aand4breact with hydroxylamines to yield a mixture ofE- andZ-oximes5and6.

ISSN:0008-4042    

DOI:10.1139/v80-020

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Active carbons which catalyze the racemization of 1,1′-binaphthyl are not effective in racemizing the 2,2′-dihydroxyl and the 8,8′-dicarbomethoxyl derivatives of binaphthyl. The 2,2′-binaphthyl methyl phosphate ester derived from optically active 1,1′-bi-2-naphthol undergoes slow thermal racemization at 190 °C (t1/2100 min, ▵H≠26.1 kcal/mol, ▵S≠−21 cal/mol deg) in triglyme and this racemization rate is also unaffected by active carbon. However, in the hydroxylic solvent 2-(2-ethoxyethoxy)ethanol at 130 °C the rate of solvolysis of the phosphate ester is increased ca. tenfold by carbon blacks or decolorizing carbon at 1 mg/mL concentration. Control experiments show that the acceleration is not due to soluble impurities released by the carbons; heterogeneous catalysis, probably by acidic and/or nucleophilic functional groups on the carbon surfaces, is invol

ISSN:0008-4042    

DOI:10.1139/v80-021

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

It is discovered that hexamethyldisilazane, a reagent generally used to silylate amino, hydroxyl, sulfhydryl, and carbonyl groups, reacts with β-diketones to form their trimethylsilyl enol ethers in high yield.An efficient and simple procedure for aminating β-triketones to their enaminodiketones by the use of hexamethyldisilazane is also described.

ISSN:0008-4042    

DOI:10.1139/v80-022

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The phosphinesand arsine(L; R = C6H5or C6H11;n = 2, 3, 4) react with iron carbonyls to afford a range of products. Simple substitution yields (L)Fe(CO)4and L2Fe(CO)3. Loss of chlorine from the ligands, symbolized (L–Cl), gives coupled complexes of formula [(L–Cl)Fe(CO)4]2and loss of chlorine and fluorine gives the η3-allyl bridged derivatives (L–Cl–F)Fe2(CO)6. Only substitution products are obtained from the cyclobutenes.

ISSN:0008-4042    

DOI:10.1139/v80-023

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Complexes with the general formula [LnM(CO)m], wherex = 0–2,n = 1 or 2, M = Mo(0) or W(0),m = 3 or 4, were prepared by thermal or photolytic methods by the reaction of the appropriate 3,5-dimethylpyrazolyl phosphine ligand with M(CO)6, norbornadienemetaltetracarbonyl [C7H8M(CO)4], cycloheptatrienylmetaltricarbonyl [C7H8M(CO)3], [(Me2N(CH2)3NMe2)M(CO)4], [(CH3CN)2M(CO)4], or [(CH3CN)3M(CO)3]. Structural evidence indicates octahedral geometry about the metal atom centre, and several modes of coordination for the ligands in those complexes isolated and characterized. Forx = 2, the ligandwas monodentate, via phosphorus inand bidentate inwhere coordination by P and the 2N site of the pyrazolyl ring yielded four-memberedmetallocycles. Forx = 1, theligand was bidentate, via the phosphorus atom and one of the 2N sites of one of the pyrazolyl substituents, thus giving the four-memberedmetallocycle inand tridentate inwhere threefacialCO's, two 2N atoms of the pyrazolyl rings, and a part of the phenyl ring occupy the six coordination sites. Forx = 0, the P(Me2pz)3ligand was tridentate via the 2N atoms of all three pyrazolyl rings, thus giving tricyclic systems [P(Me2pz)3M(CO)3] (VIII,IX).

ISSN:0008-4042    

DOI:10.1139/v80-024

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Kinetics of the reaction between nitrous acid and chlorite have been studied spectrophotometrically. The rate equation involves terms [HNO2]1.5and [ClO2−]0.5, and both an uncatalysed and a chloride ion-catalysed path have been identified. A mechanism involving peroxonitrite and hypochlorous acid as intermediates is shown to be consistent with the observations.

ISSN:0008-4042    

DOI:10.1139/v80-025

出版商:NRC Research Press    

年代:1980

数据来源: NRC