bluuebunny/crossref_metadata_2025_split huggingface dataset:
The NMR spectra of some 3‐coordinate phosphorus compounds containing chloromethyl and isopropyl groups
Authors: Bissey J. E. , Goldwhite H. , Rowsell D. G. 
Published: May 2005

AbstractAnalysis of the proton NMR spectra of Pr1PCINMe2 indicates magnetic non‐equivalence of the methyl groups due to the adjacent asymmetric phosphorus atom. High temperatures, or the addition of chloride ion, induce an exchange reaction with inversion of configuration at phosphorus. The corresponding fluoride is configurationally stable at high temperatures. The compounds CICH2PXNR2 (X = Cl, F; R = Me, Et) have non‐equivalent protons in the chloromethyl group. The two HCP coupling constants in the chlorides of this series are of opposite sign, whereas in the fluorides they are of the same sign.
PMR investigation of organic cations—I: Trithienyl methyl carbonium ions
Authors: Taddei F. , Spagnolo P. , Tiecco M. 
Published: May 2005

AbstractPMR spectral parameters are reported for the isomeric trithienyl carbonium ions. The low field shifts, relative to the corresponding carbinols, are discussed in relation to the delocalization of the positive charge into the thiophene ring bonded in position 2 or 3. A linear correlation is found between chemical shifts and π‐charge densities and the proportionality constant is higher than that previously found for benzene derivatives. Vicinal coupling constants in these systems are satisfactorily in agreement with the corresponding calculated π‐bond order.
Variable temperature magnetic resonance spectra of 1‐fluorocyclooctene
Authors: Weigert Frank J. , Strobach Donald R. 
Published: May 2005

AbstractVariable temperature fluorine magnetic resonance spectra have been obtained for 1‐fluorocyclooctene. At low temperatures both the processes of ring inversion and pseudorotation are slow on the NMR time scale, and two distinguishable conformations can be observed with a free energy difference of 95 cal/mole and a fluorine chemical shift difference of 6·7 ppm. A process with a free energy of activation of 6·1 kcal/mole interconverts the two conformations.
Kernresonanzuntersuchungen am 1.10‐Phenanthrolin und seinen Komplexverbindungen—IV: 13C‐Resonanzen des freien und protonierten 1.10‐Phenanthrolins
Authors: Rosenberger H. , Pettig M. , Madeja K. , Pehk T. , Lippmaa E. 
Published: May 2005

AbstractDie chemischen Verschiebungen der 13C‐Resonanzen für freies und protoniertes 1.10‐Phenanthrolin werden bestimmt und mit Hilfe der in Teil I1 und Teil III2 beschriebenen π‐ und (σ + π)‐MO‐Elektronenrechnungen interpretiert.Bei der Protonierung ist die Verschiebung der 13C‐Signale der dem Stickstoff benachbarten C‐Atome zu höherem Feld charakteristisch; dieser Effekt wird mit einer Verringerung der N–C‐Überlappungsbesetzung gedeutet. Für das mono‐ und diprotonierte 1.10‐Phenanthrolin wird eine relativ geringe formale Ladung am Stickstoff festegestellt (Δ = 0,0 bis 0,3).
Nuclear magnetic resonance spectra and structure of some alkyl vinyl sulphides
Authors: Ceccarelli G. , Chiellini E. 
Published: May 2005

AbstractThe NMR spectra of eight alkyl vinyl sulphides have been analyzed and the parameters compared with those obtained from an analogous series of oxygen derivatives. It is shown that a definite parallelism exists between chemical shifts and HH coupling. Difference in absolute values have been explained by mesomeric interaction magnified image involving the ability of sulphur to accommodate a decet of electrons in its valence shell. By analogy with alkyl vinyl ethers, it is possible to predict a similar correlation between the spectral characteristics and relative reactivity of vinyl sulphides in cationic polymerization.
NMR‐untersuchungen an cyclohexanen: 220 MHz‐messungen an di‐ und trisubstituierten cyclohexanen
Authors: Naegele Walter , Wendisch Detlef 
Published: May 2005

AbstractIm Zuge der Konfigurations‐ und Konformationsuntersuchungen an substituierten Cyclohexanen wurden 220 MHz‐Spektren von di‐ und trisubstituierten Verbindungen gemessen. In vielen Fällen gestattet die höhere Frequenz eine weitgehende Zuordnung aller Ringprotonen. Spezielle Eigenheiten der Spektren werden diskutiert.
A detailed evaluation of the dependence of 3J(HH) on bond angle in alkenes and cycloalkenes
Authors: Cooper M. Ashley , Manatt Stanley L. 
Published: May 2005

AbstractNewly determined and accurate data for the magnitudes of cis vinyl proton‐proton spin‐spin coupling constants in cis‐dialkylethylenes and cycloalkenes have been obtained. With these new data and also values taken from the recent literature, it has proved possible to make a critical determination of the correlation between 3J(HH) and CCH bond angles in ethylenic systems. It is suggested that it is possible to obtain accurate estimates of bond angles using NMR coupling constants, even though much more data will be required to fully substantiate this proposal. Whereas cis‐3J(HH) decreases rapidly with increasing CCH bond angles, evidence is presented that the opposite is the case for trans‐3J(HH). A brief theoretical discussion of these trends in coupling constants is given.
Die Konformativen Umwandlungen des Ungesättigten Siebenringes in 4.5.6‐Trithia‐1.2‐Benzocycloheptenen‐(1) Konformative Beweglichkeit Flexibler Ringsysteme—XVI. Untersuchungen mit Hilfe Der Protonenresonanzspektroskopie
Authors: Bredow K. V. , Jaeschke A. , Schmid H. G. , Friebolin H. , Kabuß S. 
Published: May 2005

AbstractDie Konformerengleichgewichte und die konformativen Umwandlungsprozesse des 4.5.6‐Trithia‐1,2‐benzocycloheptens‐(1) (1) sowie seiner 3′.6′‐Dimethoxy‐, 3′.6′‐Dimethyl‐ und 3′.6′‐Diphenyl‐ derivate (2, 3 und 4) wurden PR‐spektroskopisch untersucht. Die Lösungen dieser Substanzen sind Gleichgewichtsgemische zweier Konformerer, von denen das eine vermutlich Sesselform, das andere Wannenform hat. Der Wert der freien Konformationsenthalpie ΔGw des Wannenkonformeren ist abhängig von der Größe der Substituenten R in 3′‐ und 6′‐Stellung. ΔGw beträgt für R = H 1,03 kcal/Mol, R = OCH3 0,82 kcal/Mol, R = C6H5 0,50 kcal/Mol und R = CH3 −0,19 kcal/Mol. Durch Kristallisation bei +60° kann im Falle der substituierten Trithiabenzocycloheptene jeweils ein reines Konformeres in kristalliner Form erhalten werden. Beim Dimethoxyderivat kristallisiert das Sesselkonformere, beim Dimethyl‐ und dem Diphenylderivat das Wannenkonformere aus. Nach Auflösen der Kristalle erfolgt Einstellung des Konformerengleichgewichts; bei 0°C betragen die Halbwertszeiten 2 bis 15 Minuten. Anhand der Temperaturabhängigkeit der Protonenresonanzen kann experimentell zwischen zwei verschiedenen konformativen Umwandlungsprozessen unterschieden werden: Der langsamere Prozess wird der Version, der schnellere der Pseudorotation des Siebenringes zugeordnet. Die freie Aktivierungsenthalpie ΔGv≠ der Version wurde im Falle des 4.5.6‐Trithia‐1.2‐benzocycloheptens‐(1) nach der ‘line‐shape’‐Methode, im Falle des Diphenylderivates nach der ‘Äquilibrierungs’‐Methode bestimmt. Die beiden anderen Verbindungen wurden mit beiden Methoden untersucht. Die mit den verschiedenen Methoden bestimmten ΔGv≠‐Werte stimmen gut überein. Die freie Aktivierungsenthalpie der Version ΔGv≠ unmd diejenige der Pseudorotation ΔGP≠‐Werte ≤ 11,4 kcal/Mol.
Proton resonance spectra of heterocycles—VII: Proton NMR spectra of 2‐methyl‐benzoxazoles,‐benzothiazoles and ‐benzoselenazoles
Authors: Katritzky A. R. , Takeuchi Yoshito 
Published: May 2005

AbstractChemical shifts and coupling constants are reported for a series of the title compounds and the effects of substituents on these values correlated with the corresponding effects in benzenes. Partial bond fixation in these and other benzo‐heterocycles is discussed together with the general prediction of NMR parameters in substituted heterocycles.
NMR study of 4‐deoxy‐α‐L‐threo‐4‐enohexopyranosyluronic acid (1 → 3)2‐acetamido‐2‐deoxy‐D‐hexoses produced in the enzymic digestion of hyaluronate, chondroitin and chondroitin sulfates
Authors: Hirano Shigehiro 
Published: May 2005

AbstractThe conformation of 4‐deoxy‐α‐L‐threo‐4‐enohexopyranosyluronic acid (1 → 3)2‐acetamido‐2‐deoxy‐d‐hexoses was analyzed by NMR spectroscopy. The half‐chair (H12) conformation was found in the unsaturated uronide moiety and the chair (Cl) conformation in the hexosamine moiety.
Multiple NMR analysis of the affinin
Authors: Correa J. , Roquet S. , Díaz E. 
Published: May 2005

AbstractThe configuration of the insecticidal and medicinal lipid ‘affinin,’ N‐isobutyldeca‐trans‐2, cis‐6, trans‐8‐trienamide, may be assigned in an unequivocal manner by NMR spectroscopy. The spectral data and the advantages of the multiple irradiation methods are presented and discussed.
The NMR spectra of some 1,3‐oxathians and the influence of heteroatoms on the coupling constants of adjacent protons
Authors: Allingham Y. , Crabb T. A. , Newton R. F. 
Published: May 2005

AbstractThe preparation of 4‐phenyl‐1, 3‐oxathian, 6‐methyl‐1, 3‐oxathian, and some of their 2‐substituted derivatives is described. Significant features of their NMR spectra are discussed with particular reference to the influence of the heteroatoms on the coupling constants of adjacent protons.
A systematic approach to the AA′BB′, AA′BB′MX and derived systems in nuclear magnetic resonance
Authors: Batterham T. J. , Bramley R. 
Published: May 2005

AbstractThe AA′BB′ and AA′BB′MX nuclear magnetic resonance spin systems for I = ½ nuclei have been analysed. Expressions for the transition frequencies and intensities have been obtained which have the maximum accuracy consistent with practicable use. The analyses have been applied respectively to a hypothetical AA′BB′ nuclear spin system and to the two molecules para‐ fluoro‐phenyldichlorophosphine and tris‐para‐fluorophenylphosphine. Inconsistencies in earlier treatments of the AA′BB′ system have been clarified.
Nuclear magnetic resonance spectroscopy. Analysis of the 1H and 13C spectra of Br13CH213CH2Br
Authors: Carhart Raymond E. , Roberts John D. 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of 1,2‐dibromoethane‐13C2 have been analyzed to determine the magnitude (38·9 Hz) and sign (positive) of 1J(CC) relative to those of 3J(HH) (positive). This type of coupling appears to be rather insensitive to the presence of bromine or methyl as substituents on the carbons.
A line width method for determining chemical exchange rates from NMR spectra
Authors: Ramey Kermit C. , Louick David J. , Whitehurst Philip W. , Wise William B. , Mukherjee Rabindranath , Moriarty Robert M. 
Published: May 2005

AbstractThe applicability of W½, the line‐width at one‐half height corrected for field inhomogeneity and couplings, for characterization of nuclear magnetic resonance line shapes generated by exchange averaging of chemical shifts has been investigated for the case PA= PB. The Gutowsky‐Holm equation, simplified by the assumption of a large T2º such that T= 0, was used to produce a family of curves relating W½corrected to the rate of exchange for various ΔvABvalues.The rate of internal rotation about the CN amide bond has been studied in neatN,N‐dimethyl‐formamide between 79·5 and 159° by the W½method and the results, Ea= 24·9 and 24·1 Kcal/mole at 60 and 100 MHz do not agree with those recently reported by Rabinovitz and Pines, Ea= 20·5 Kcal/mole obtained by the total line shape method. For neatN,N‐dimethylacetamide and for solutions of DMA in dimethylsulfoxide‐d6, application of the W½method yielded Ea, ΔH‡ and ΔS‡ values which are in excellent agreement with those obtained by Neuman and Jonas for DMA‐dεusing a total line shape analysis. The thermodynamic parameters for neatN,N‐dimethylcarbamoyl chloride obtained by the total line shape and W½methods are also in excellent agreement, 16·4 and 16·8 Kcal/mole for Eaand 15·8 and 16·2 Kcal/mole for ΔH‡, respectively.The W½method was also used for the determination of the activation parameters for rotation about the carbon‐nitrogen bond in the following thioamides:N,N‐dimethylthiobenzamide, (Ea= 19.8 Kcal/mole),N,N‐diethylthiobenzamide, (Ea= 20·4 Kcal/mole),N,N‐dimethylphenylthio‐acetamide (Ea= 21·4 Kcal/mole). The results obtained for these thioamides are compared with the corresponding amides. SpecificallyN,N‐dimethylbenzamide andN,N‐diethylbenzamide were studied using the W½method and activation energies for rotation about the carbon‐nitrogen bond of 17·5 and 15·6 Kcal/mole, respectively, were found. The relative magnitudes of these parameters are discussed on the basis of molecular geometry of the thioamides. Attention is drawn to the fact that for structurally related amides and thioamides, the barrier heights for internal rotation are not greatly different.
Geminal coupling constants in methylene groups α to nitrogen in indolizidine, quinolizidine and related systems
Authors: Cahill R. , Crabb T. A. , Newton R. F. 
Published: May 2005

AbstractValues of J(5a—5e) for indolizidine and related systems show that, contrary to results described in an earlier communication, these couplings do not differ markedly from the corresponding geminal coupling constant in quinolizidine.
An interpretation of 1H and 13C chemical shifts in substituted benzenes on the basis of M.O. charge densities
Authors: Lazzeretti P. , Taddei F. 
Published: May 2005

AbstractThe results of an MOLCAO calculation on both σ and π electron systems of several substituted benzenes are reported. The charge densities obtained reproduce the dipole moments of the molecules examined, provided that substituents with strong mesomeric effects are not present. It is shown that there is a satisfactory agreement between 13C and 1H chemical shifts and the trend of total charge densities for all positions of substituted benzenes.
Etude par RMN d'une Serie d'Indoanilines et d'Indophenols
Authors: Canet D. , Granger P. , Bugaut A. , Estradier F. 
Published: May 2005

AbstractNous rapportons les résultats de l'étude RMN de 25 indoanilines et indophénols. Ces mesures nous permettent de préciser les formes tautomères stables et de donner la position des différents substituants sur les cycles.
Protonenresonanzuntersuchungen an Tellur‐, Schwefel‐ und Sauerstoff‐substituierten Benzolderivaten
Authors: Müllen Klaus 
Published: May 2005

AbstractDie Protonenresonanzspektren von o‐Phenylen‐bis[p‐äthoxy‐phenyltellurid], o‐Dimercapto‐benzol und p‐Hydroxy‐mercapto‐benzol sind vollständig analysiert worden. Die Einflüsse der TeR‐, SR‐ und OR‐Gruppen in den analogen Benzolderivaten (1) bis (4) werden anhand spezifischer Substituenten‐Inkremente diskutiert.
Proton magnetic resonance spectra of methylacridines. The relative signs of the inter‐ring coupling constants
Authors: Sciacovelli O. , von Philipsborn W. 
Published: May 2005

AbstractHigh‐resolution proton spectra of acridine and the five monomethyl derivatives have been analyzed using multiple resonance and computer techniques. It was possible to determine the magnitudes and relative signs of the inter‐ring coupling constants between H‐C(9) and all the protons of the adjacent rings. Positive signs have been obtained for 5J29 and 5J49, negative signs for 4J19 and 6J39. The coupling constants are discussed in terms of σ‐ and π‐contributions and as a function of the geometry of the pathway.
Chemical polarization of nuclei. PMR spectra of decomposition products of dimethyl peroxydiphthalate
Authors: Kessenikh A. V. , Rykov S. V. , Starostin E. K. , Nikishin G. I. 
Published: May 2005

AbstractChemical polarization of protons was observed in methyl benzoate formed during the thermal decomposition of dimethyl ester of peroxydiphthalic acid. The polarization pattern of methyl benzoate aromatic protons was very different in this case from that observed during the thermal decomposition of acetyl benzoyl peroxide. The unpolarized products formed from the methoxy radical, CH2O and CH3OH, were found in the mixture of decomposition products of this peroxide and were identified by means of PMR spectroscopy.
NMR parameters of sulphur heterocycles: Solvent and concentration effects for thiophen and related systems
Authors: Ewing D. F. , Scrowston R. M. 
Published: May 2005

AbstractInfinite dilution data for six sulphur heterocycles have been obtained from second order analyses of their NMR spectra in CS2, CDCl3, CD3COCD3, or C6D6. Use of LAOCOON3 leads to accurate chemical shifts, but substantial errors remain in some of the coupling constants. Evidence is presented of specific association of chloroform with the sulphur heterocycles and of the interaction of acetone with the sulphur atom. An apparently anomalous geometry for the complex of benzene with thiophen and with other solutes is discussed. Dilution effects are considered in relation to the formation of solute dimers.
Synthesis and NMR analysis of 2,4‐dichloro‐1‐pentene and of 2,4‐dichloro‐1‐pentene‐1‐d1
Authors: Gurato Giorgio , Rigo Adelio 
Published: May 2005

AbstractThe compound 2,4‐dichloro‐1‐pentene‐1‐d1 (1) was synthesized starting from and CHCNa. In the last stage of the synthesis on activated carbon‐HgCl2 catalyst), (3) were formed together with (1).The NMR parameters of (1), its cis and trans isomers and (2) were obtained in C6D6 solution at 100 MHz. Theoretical spectra of (1) at 60 MHz were simulated with the aid of a computer, using as input the NMR parameters obtained at 100 MHz and good agreement with the experiment was obtained.
The NMR spectrum and conformation of 2,3‐difluoropropionic acid ethyl ester
Authors: Hägele G. , Harris R. K. , Sartori P. 
Published: May 2005

AbstractThe 1H and 19F NMR spectra of the CH2FCHF group in FCH2CHFCO2C2H5 were analysed on the basis of an ABCXY spin system. The non‐equivalence of the methylene protons is discussed in terms of rotational isomerism. It is concluded that the dominant rotamer is probably considerably distorted from a perfectly staggered orientation. The variation of 3JHF with substituent electronegativity is reviewed.
Conformation of substituted five‐membered rings
Authors: Dradi Emanuele , Gatti Giuseppe 
Published: May 2005

AbstractProton magnetic resonance chemical shifts and coupling constants for some 5‐substituted dihydrofurans, dihydrofuran and dihydrothiophene fused rings are reported, the substituents being methyl, ethyl and phenyl.The observed coupling constants are consistent with buckled rings, in which it appears that a conformation with pseudo‐equatorial substituents is predominant.
Proton magnetic resonance spectra of thenyl derivatives—II. Chloromethylthiophenes and some dithienylmethanes
Authors: Sone Tyo , Takahashi Kensuke 
Published: May 2005

AbstractPMR spectra of thirty‐eight chloromethylthiophene and seven dithienylmethane derivatives were observed at 60 or 40 MHz. The chemical shifts of methylene protons were 4·63 to 5·25 ppm for monosubstituted 2‐chloromethylthiophenes and 4·37 to 4·56 ppm for monosubstituted 3‐chloromethylthiophenes, respectively, with reference to TMS. Those for 2,2′ ‐dithienylmethanes, which have one substituent in each ring, were 4·12 to 4·34 ppm. These shifs are useful for determination of the positions of the methylene groups in the related compounds. The long‐range coupling constants observed for methylene proton signals are also useful for the determination of the positions of substituents.
Pentafluorobutane; an example of long‐range five bond HF coupling
Authors: de Marco A. , Gatti G. 
Published: May 2005

AbstractThe complete analysis of the spectrum of 2,2,4,4,4‐pentafluoro‐n‐butane is reported. From the sum of the vicinal proton‐fluorine coupling constants an estimate of the conformational energy has been obtained and successively the long‐range coupling of the individual conformers has been calculated.
NMR studies on the interaction of ethyl‐aluminium chlorides with some methyl‐substituted pyridines
Authors: Matsubayashi Gen‐Etsu , Wakatsuki Kizuku , Tanaka Toshio 
Published: May 2005

AbstractThe interaction of triethylaluminium, diethylaluminium chloride and ethylaluminium dichloride with some methyl‐substituted pyridines has been investigated in 1,2‐dichloroethane or dichloromethane by means of NMR spectroscopy. 2,6‐Dimethyl‐ and 2,4,6‐trimethyl‐pyridine have been found to form three types of complexes with diethylaluminium chloride and ethylaluminium dichloride in solution. In addition, the configurations of the complexes in solution have been estimated from proton NMR chemical shifts of the methyl‐substituted pyridines and the conductivity measurements.
Protonenresonanz‐spektroskopische Untersuchungen an substituierten Cyclobutenen. Ein Beitrag zur Kenntnis der Bindungsverhältnisse im komplex‐gebundenen Cyclobutadien
Authors: Hüther Hans , Brune Hans Albert 
Published: May 2005

AbstractDie vollständigen Protonenresonanz‐Spektren—einschließlich aller beobachtbaren 13CH‐Kopplungen wurden für eine Reihe substituierter Cyclobutene, Methylen‐cyclobutene und Bismethylen‐cyclobutene aufgenommen und zugeordnet. Die Meßergebnisse werden im Hinblick auf die Bindungsverhältnisse im durch Komplexbildung stabilisierten‐Cyclobutadien diskutiert.
PMR spectra of dimers of cyclopentadienyl compounds
Authors: Sergeyev N. M. , Avramenko G. I. , Korenevsky V. A. , Ustynyuk Yu A. 
Published: May 2005

AbstractThe PMR spectra of cyclopentadine endo‐dimer, its 1y‐acetoxy‐derivative and the dimer of spiro‐heptadiene have been thoroughly studied. The assignment is proved by the use of spindecoupling experiments and the INDOR‐technique. The relative signs of several coupling constants were found and used for the assignment. General trends in the proton chemical shifts and coupling constants are discussed for the derivatives of the cyclopentadiene dimer and for the substituted cyclopentadiene dimers.
Determination Rapide de la Configuration Cis Trans des Alcenes CHCHCH Utilisation des Complexes de Terres Rares
Authors: Martin G. J. , Naulet N. , Lefevre F. , Martin M. L. 
Published: May 2005

AbstractDans les composés de structure
equation image
Z CHCHCHY la complexité du spectre rend souvent difficile l'obtention du couplage J(HCCH) et donc l'identification de la configuration. L'étude de nombreux dérivés de ce type préparés par des méthodes stéréospécifiques montre qu'à de rares exceptions près, le déplacement chimique δ CH(Z) de l'isomère cis est supérieur à δCH(Z) de l'isomére trans. Dans le cas des alcools R CHCH CHOH R′ les isoméres configurationnels ont des comportements différents en présence de complexes d'europium ou de praseodyme, holmium et dysprosium. Si le spectre des isoméres trans reste fortement couplé en présence de complexe l'obtention de 3J(HCCH) devient aisée dans les composés cis.
Magnetic non‐equivalence in carbinols of the general formula R1R2C(OH)CH2OR (1H and 13C NMR)
Authors: Dabrowski Janusz , Ejchart Andrzej 
Published: May 2005

AbstractSeveral compounds of the general formula R1R2C(OH)CH2OR containing different geminal group systems have been investigated in proton and carbon magnetic resonances at variable temperatures. The role of steric factors, viz. of the size of substituents and the distances between different parts of the molecules, have been discussed.
Resonance des Phospholes—Reaction Avec le n‐Butyl Lithium
Authors: Mathey F. , Mankowski‐Favelier R. 
Published: May 2005

AbstractSept phospholes ont été préparés par une méthode en deux étapes précédemment décrite. Sur la base de données de RMN du proton et du phosphore, on a essayé de classer ces phospholes suivant leur degré d'aromaticité. On a fait réagir deux d'entre eux avec le n‐butyl lithium. On a observé une attaque nucléophile sur le phosphore et sur les doubles liaisons. Ces faits sont expliqués par un accroissement des conjugaisons p—π et pπ—dπ entre le phosphore et le système diénique par comparaison avec les vinyl phosphines.Les données RMN semblent en accord avec cette façon de voir. Les influences de la substitution et de la délocalisation du doublet du phosphore sur le δ 31P ont été interprétées dans le cadre du formalisme de Letcher et Van Wazer.