bluuebunny/crossref_metadata_2025_split huggingface dataset:
A two frequency method for the interpretation of multiple NQR spectra
Authors: Grechishkin V. S. , Shishkin E. M. , Shishkin V. A. , Kjunzel I. A. 
Published: May 2005

AbstractA new method for the interpretation of NQR spectra is described. The indentification of multiple lines belonging to different transitions \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{2} \to \frac{3}{2}{\rm and}\frac{3}{2} \to \frac{5}{2} $\end{document}is carried out by using the ‘seizure’ of the corresponding low or high frequency transitions in a two‐frequency pulse experiment.
Wannier spin excitons in charge‐transfer complexes
Authors: Alikin A. A. , Grechishkin V. S. , Grechishkina R. V. , Gusarov V. M. 
Published: May 2005

AbstractElectron spin resonance in some charge‐transfer complexes of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) with sulphanilamides and antibiotics has been investigated.The ESR spectra are caused by two types of paramagnetic centres: the impurity type and the thermally excited type (Wannier spin excitons).
Etude RMN de l'Acetone en Solution dans une Phase Nematique
Authors: Courtieu J. , Gounelle Y. 
Published: May 2005

AbstractLe spectre RMN de l'acétone orientée dans le p‐(p′ ethoxyphenyloxycarbonyl)phényl carbonate de butyle est étudié dans l' intervalle de température 48° à 58°C. La mesure des constantes de couplage direct permet de calculer les facteurs d' orientation moléculaires; ceux‐ci permettent de mettre en évidence ici l' intervention de la polarisabilité dans le phénoméne d' orientation.
Nuclear magnetic resonance studies of methyl‐5, 6‐dicarboxy‐2‐norbornene derivatives
Authors: Kamezawa Norimasa , Ueda Toyoichi 
Published: May 2005

AbstractA simple procedure is provided for the quantitative analysis of Diels‐Alder adduct prepared from commercial methylcyclopentadiene and maleic anhydride by NMR spectra without further separation of its components. The adduct is considered as a mixture of endo norbornene derivatives (Cn), (Dn), (E) and (Fn) which are obtained from 1‐, 2‐ and 5‐methylcyclopentadiene and cyclopentadiene, respectively.The quantitative analysis of the adduct can be made on a basis of the ratio of the signal intensities of the olefinic protons in the adduct. The result shows that the adduct prepared under mild conditions mainly consists of three norbornene derivatives (Cn), (Dn) and (Fn), with a negligibly small amount of (E). When the adduct prepared under mild conditions is heated, it contains the exo isomers (Cx), (Dx) and (Fx). The ratio of the endo and the exo norbornene derivatives, i.e. ((Cn) + (Dn) + (Fn)):((Cx) + (Dx) + (Fx)), may be estimated from the signal intensities of the 5‐ and 6‐protons.As the result of the analyses of the adducts which are obtained by heating at different temperatures the adduct prepared under mild conditions, the mole fraction of 2‐methyl isomers (Dn) and (Dx), which is found to be 58 % in the adduct prepared at − 15°C, keeps on increasing with rising temperature and shows almost the same value, ∼86%, when heated above 150°C. Therefore, the equilibrium between 1‐methyl and 2‐methyl isomers does not change above 150°C. On the other hand, the isomerization from endo to exo isomers is not found below 110°C, and then exo isomers keep on increasing above 140°C.
Etudes RMN en Serie Heterocyclique—VIII: Effet des Dipivalomethanates de Nickel(II), Cobalt(II), Europium(III) et Praseodyme(III) sur les Deplacements Chimiques de quelques Derives du Pyrazoles
Authors: Claramunt Rosa‐Maria , Elguero José , Jacquier Robert 
Published: May 2005

AbstractOn a déterminé l'effet produit par quatre réactifs de déplacement sur les signaux de sept derivés du pyrazole et sur ceux du methyl‐ 1 imidazole. Ces effets sont discutés en fonction de leur utilité pour différencier des structures isomères.
Shielding constants of tin 119Sn nuclei
Authors: Tupčiauskas A. P. , Sergeyev N. M. , Ustynyuk Yu. A. 
Published: May 2005

AbstractA number of organotin compounds have been studied using the heteronuclear double resonance H1‐{Sn119}. The tin chemical shifts have been tabulated and discussed on the basis of the concept of electronegativity. The highfield displacement is found attributable to the filling of the 5d‐orbitals of the tin atom.
The determination of aromatic substitution patterns by nuclear magnetic resonance
Authors: Zanger M. 
Published: May 2005

AbstractA method is described which permits the analysis of many substituted benzene compounds. The method is useful for mono‐through tetra‐ substituted aromatics. In ideal cases, the number and disposition of the substituents and the chemical shifts of the residual protons can be accurately determined. The method assumes approximate first order couplings and is useful for roughly 50% of all aromatics. Frequently observed anomalous spectra are also discussed.
Aminophosphines: Influence des Substituants lies au Phosphore sur la Barriere a la Rotation Autour de la liaison PN et sur la Nucleophilie de L'atome D'azote
Authors: Simonnin Marie‐Paule , Charrier Claude , Burgada Ramon 
Published: May 2005

AbstractL'étude par RMN de la rotation autour de la liaison PN dans diverses aminophosphines permet de mettre en évidence l';influence des substituants liés au phosphore sur les valeurs de ΔG*. Le parallélisme observé entre la barrière à la rotation et la grandeur des couplages 3J(PNCH) montre que les variations de ΔG* reflètent principalement l'importance du recouvrement pπ—dπ.Une étude de la nucléophilie de l'azote, par réaction d'échange aprotique entre le trifluoroacétate de méthyle et diverses aminophosphines, confirme ces conclusions.
Conformational studies by nuclear magentic resonance—II: The effect of steric factors on hindered rotation in enamino aldehydes and ketones
Authors: Dabrowski J. , Kozerski L. J. 
Published: May 2005

AbstractRotational barriers of the dimethylamino group in different enamino aldehydes and ketones have been applied for evaluation of their conformation. It has been maintained that repulsion between bulky substituents causes twisting of the molecule rather than planar deformations. Arguments for and against these alternative concepts based on the analysis of JHH and J(13CH) coupling constants in different fragments of the molecule have been discussed.
13C, 14N, 15N and 17O NMR spectra of nitropyrroles and nitroimidazoles
Authors: Lippmaa E. , Mägi M. , Novikov S. S. , Khmelnitski L. I. , Prihodko A. S. , Lebedev O. V. , Epishina L. V. 
Published: May 2005

AbstractCarbon, nitrogen and oxygen NMR spectra of some nitro derivatives of pyrrole and imidazole have been investigated. The 13C chemical shifts of para‐carbons and the 17O chemical shifts of the nitro group correlate qualitatively with the electron densities on these carbon and oxygen atoms, which in turn depend upon the degree of conjugation of the nitro groups with the heterocyclic ring. Conjugation of several nitro groups with the benzene ring is in most cases not impaired by mutual interactions and the 13C shifts show good additivity. Such additivity is much worse in pyrrole and imidazole derivatives. Taken together with the diamagnetic nature of these deviations from additivity, this leads to a possible conclusion about the less pronounced conjugation of the nitro groups with the heterocyclic ring in heterocyclic dinitro derivatives.
Heteronuclear multiple magnetic resonance studies of quaternary ammonium salts derived from heterocyclic bases
Authors: McFarlane H. C. E. , McFarlane W. 
Published: May 2005

Abstract14N tickling experiments performed with simultaneous decoupling of substituent protons are used to show that 2J(14NHortho) and 3J(14NHmeta) are both positive in the N‐methyl pyridinium ion and related species. Long range coupling extending over as many as five bonds is observed between N‐methyl protons and ring protons in 14N‐decoupled spectra. Triple resonance decoupling is used to permit an analysis of the AA′MM′ spin system given by the ring proton of N‐methyl pyrazinium iodide.
4J(HH)‐Kopplungen und Magnetisch Nichtäquivalente Methylenprotonen in Einigen 1,3‐oxathiolan‐5‐on‐Derivaten
Authors: Brink Maud 
Published: May 2005

Abstract4J(HH)‐Kopplungen und magnetisch nichtäquivalente Methylenprotonen in einigen 1,3‐Oxathiolan‐5‐on‐ Derivaten wurden in vershiedenen Lösungsmitteln studiert.
Proton magnetic resonance studies of compounds with bridgehead nitrogen atoms—XVIII Configurational and conformational studies with derivatives of hexahydroindolizin‐2(3H)‐one
Authors: Cahill R. , Crabb T. A. 
Published: May 2005

AbstractA series of substituted hexahydroindolizin‐2(3H)‐ones and some related ketones have been prepared by Dieckmann condensation of the appropriate diesters. Utilising spectral data, the configurations of these compounds have been assigned, and their conformations discussed with particular reference to the magnitude of the geminal coupling constant (Jgem) for the NCH2C(O) protons. With the exception of tetrahydropyrrolizin‐2(3H)‐one, all the ketones in this study are shown to exist in predominantly trans‐fused conformations. In the case of hexahydroindolizin‐2(3H) one and hexahydro‐2H‐quinolizin‐3 (4H)‐one, the separate contributions to Jgem from the adjacent N lone pair and the carbonyl π electrons are discussed.
Proton magnetic resonance studies of compounds with bridgehead nitrogen atoms—XIX Configurational and conformational studies with derivatives of hexahydropyrido [2,1‐c][1,4]oxazin‐4(3H)‐ones
Authors: Cahill R. , Crabb T. A. 
Published: May 2005

AbstractA series of substituted hexahydropyrido [2,1‐c][1,4]oxazin‐4(3H)‐ones has been prepared by reaction of the sodio derivative of the appropriate piperidyl carbinol with ethyl chloroacetate. From a study of their NMR spectra the configurations of these compounds have been assigned and the conformation of the perhydro‐1, 4‐oxazinone moiety shown to be that with the ring oxygen atom and the angular hydrogen on the same side of the plane defined by C3C(O)N. The synthesis and NMR spectra of hexahydro‐2H‐pyrido [1,2‐d][1,4]oxazepin‐5(4H)‐one, 1,6,11,11a‐tetrahydro [1,4]‐oxazino [4,3‐b]isoquinolin‐4(3H)‐one and of hexahydropyrido [2,1‐c][1,4]thiazin‐4(3H)‐one are also discussed. cis‐6,9a‐H‐6‐Methyl‐hexahydropyrido[2,1‐c][1,4]oxazin‐4(3H)‐one is shown to exist in a conformation containing a deformed perhydropyridine ring.
Benzene dilution shifts and steric interactions in N,N‐dialkylamides
Authors: Graham Laurine L. , Miller Michael R. 
Published: May 2005

AbstractThe NMR spectra of ten disubstituted amides have been recorded at 0°C in carbon tetrachloride and in benzene solutions. The benzene dilution shifts (ASIS) and proton spin decoupling were used to make the chemical shift assignments. A time‐averaged solvent cluster model for the association between the amide and benzene is consistent with the observed ASIS values. The assignments for the N‐methine and N‐methyl resonance peaks in RCON[CH(CH3)2]2, where R is methyl, ethyl or propyl are inverted from the assignments for N,N‐diisopropylformamide (R  H).
Natural abundance 13C NMR investigation of substituted bromobenzene using noise decoupling of proton resonances
Authors: Hinton J. F. , Layton B. 
Published: May 2005

AbstractThe natural abundance 13C NMR spectra of bromobenzene and ten derivatives have been obtained using the technique of noise modulated decoupling of the proton resonances. Assignments have been made for all 13C resonance signals using an additivity rule. The chemical shifts of the aromatic carbon nuclei in the para‐substituted compounds are discussed in terms of the Taft parameters (σR, σI) and the electronegativity of the substituent.
An NMR study of the conformational equilibrium of 5‐fluoro‐1,3‐dioxan in solution. Dependence on solvent
Authors: Hall L. D. , Johnson R. N. 
Published: May 2005

AbstractThe 1H and 19F NMR parameters of 5‐fluoro‐1,3‐dioxan (1) dissolved in a number of solvent systems are interpreted on the basis of fast inversion between two chair conformations. In cyclohexane solution the two chair conformations are almost equally populated, whereas in more polar solvents, such as chloroform, the conformation having the fluorine substituent in an axial position is strongly preferred. Addition of acetic acid to a solution of 1 in cyclohexane increases the preference of the fluorine substituent for the axial orientation. Possible reasons for these observations are discussed.
Determination Empirique de l'Effet d'Anisotropie Diamagnetique Exerce sur les Protons Aliphatiques en Resonance Magnetique Nucleaire—II
Authors: Gouverneur P. , Nagy O. B. , Soumillion J. Ph. , Burton T. , Bruylants A. 
Published: May 2005

AbstractLa corrélation empirique δ =
equation image
est étendue à un grand nombre de composés halogénés et de nouvelles corrections d'anisotropie diamagnétique sont déterminées. La signification de ces corrections est discutée et une analyse soignée des données permet de fixer les limites de la méthode.
Anisochronism of large geminal groups in the 1H and 13C nuclear magnetic resonance spectra
Authors: Biernacki Wladyslaw , Da̧browski Janusz , Ejchart Andrzej 
Published: May 2005

AbstractThe role of steric factors in magnetic non‐equivalence anisochronism of complex geminal groups and of their fragments in compounds of the general formula RCH(Ph)CH(COOR′)2 has been investigated. CMR anisochronism is more sensitive to conformational and other steric changes than is PMR.
An NMR study of phenol self‐association
Authors: Bogachev Yu. S. , Vasianina L. K. , Shapet'ko N. N. , Alexeeva T. L. 
Published: May 2005

AbstractThis paper presents a study of the chemical shift of the phenol hydroxyl group as a function of concentration and temperature in cyclohexane, methylcyclohexane and carbon tetrachloride solutions. The chemical shift of monomeric phenol has been found. For these solutions monomertrimer equilibrium is observed within the entire temperature range and within a wide concentration range. At low phenol concentrations, from 1 to 3 mole‐%, the monomer‐dimer equilibrium is observed in cyclohexane, methylcyclohexane and carbon tetrachloride solutions. Chemical shift of the hydroxyl group of trimeric phenol is temperature‐dependent.From the experimental data the association constants and thermodynamic functions of the systems under study have been determined. The association constants differ for the above systems at the same temperatures. Association entropy ΔS changes from one system to another, while ΔH is the same for all systems.
Conformation et Spectrometrie de RMN
Authors: Wylde Renée , Cerveau Geneviéve 
Published: May 2005

AbstractL'examen des spectres de RMN des quatre diméthylamino‐3‐décalols‐2‐trans et des iodures d'ammonium quaternaires correspondants permet d'envisager pour ces composés une déformation de l'un des cycles de la décaline trans habituellement double chaise.Cette déformation est apparente specialement dans le cas de l'isomère cis à groupements hydroxyle equatorial et diméthylamino axcial, pour lequel on propose une conformation ‘chaise aplatie'. Le passage à l'ammonium quaternaire accentue entre deformation jusqu’à la conformation chaise‐bateau ou préférentiellement chaise croisée.
The NMR spectra and conformations of cyclic compoundsV: Proton couplings and chemical shifts in bridged cyclobutanes
Authors: Abraham R. J. , Cooper M. A. , Salmon J. R. , Whittaker D. 
Published: May 2005

AbstractThe PMR spectra of twelve pinene derivatives are reported, analysed and assigned.The proton couplings in the bridged cyclobutane group are compared with those of other strained cyclobutanes, and the relationship between 2JHH and the C.CH2.C angle is shown to be anomalous in these systems, suggesting unusually small H. C. H. angles in cyclobutanes.The very large values of 4JHH (eq‐eq) in buckled cyclobutanes are interpreted in terms of current M. O. theory and also given a simple geometric rationalisation based on the direct mechanism.The various couplings in the pinene skeleton are discussed in terms of present theories and minor conformational effects in these molecules. Substituent chemical shift (SCS) values for Me and OH groups around the pinene skeleton are obtained, and shown not to agree with calculations based on present theories of chemical shifts.
Interpretation du Spectre RMN de l'Octaacetate de Cellobiose a 250 MHz. Application au Triacetate de Cellulose
Authors: Dunand J. , Gagnaire D. , Odier L. , Vindendon M. 
Published: May 2005

AbstractNous avons interprété totalement le spectre de RMN de l'α octaacétate de cellobiose en effectuant le spectre à 250 MHz et en utilisant la technique de double irradiation. Les 14 protons des deux cycles ont été attribués.L'octaacétate de cellobiose étant le premier modèle du triacétate de cellulose, cette interprétation nous a permis d'attribuer à L'extrémité anomère du triacétate tous les protons se trouvant à champ faible dans son spectre RMN.
Analysis of the PMR spectrum of 1,4‐naphthoquinone in a nematic solvent
Authors: Dereppe Jean‐Marie , Degelaen Jacques , van Meerssche Maurice 
Published: May 2005

AbstractThe analysis of the PMR spectrum of 1,4‐naphthoquinone dissolved in the nematic phase of pp′‐di‐n‐hexyloxyazoxybenzene showed that the naphthoquinone molecule is planar. The ratios of the various interprotonic distances were determined.
13C‐NMR‐chemische Verschiebungen von Polymethinen. Elektronenstruktur und Lösungsmitteleinfluss
Authors: Radeglia R. , Engelhardt G. , Lippmaa E. , Pehk T. , Nolte K.‐D. , Dähne S. 
Published: May 2005

AbstractDie 13C‐NMR‐chemischen Verschiebungen von einfachsten Polymethinen bestätigen die alternierende Elektronendichteverteilung bei diesen Verbindungen. Die Verschiebungen polarer Merocyanine sind von der Polarität des Lösungsmittels abhängig und beweisen damit eine lösungsmittelinduzierte Veränderung der Elektronenstruktur.
Confirmation of the E and Z attribution to the isomers of 3‐ethylidene‐1‐azabicyco‐[2,2,2]octane by CMR spectroscopy
Authors: Van Binst G. , Tourwe D. 
Published: May 2005

AbstractCMR spectra of the following bicyclo[2,2,2]octane compounds were measured: 1‐azabicyclo[2,2,2]octan‐3‐one (3), 2‐azabicyclo[2,2,2]octan‐3‐one (5), bicyclo[2,2,2]octaone (4), 3‐ethyl‐1‐azabicyclo[2,2,2]oct‐2‐ene (6) and of the Z and E isomers of 3‐ethylidene‐1‐azabicyclo‐[2,2,2]octane (1 and 2). The attribution of the signals and confirmation of the Z and E configuration of isomers (1) and (2) is described.
The structure of 2‐arylamino‐2‐thiazolines, analogous thiazines and their amides—X. An IR and NMR investigation of the N‐methyl derivatives
Authors: Sohár P. , Toldy L. 
Published: May 2005

AbstractThe isomer‐pairs of the 2‐arylamino‐2‐thiazolines and ‐thiazines, carrying a methyl substituent on the nitrogen atom of the ring and outside the ring were synthesised by unambiguous routes. An IR and NMR investigation of these compounds revealed the fact that the NMR signal of the 2,6‐symmetrically substituted aryl group can be used advantageously for the determination of the isomeric structures. The AB2 multiplet of the aromatic protons is shifted towards the AX2 pattern in the b isomer—containing a conjugated CN bond outside the ring—as compared to the a isomers. The structure of this multiplet does not depend on the size of the hetero‐ring.
Studies of polarised ethylenes—IV: Barriers to rotation around formal double bonds and formal single bonds in 1, 1‐bis‐dimethylaminoethylenes
Authors: Wennerbeck I. , Sandström J. 
Published: May 2005

Abstract1, 1‐Bis‐dimethylaminoethylenes with electron attracting substituents on C2 show rotations around the CC and CN bonds, the rates of which are in most cases measurable by the NMR line shape method. The temperature‐dependent four‐and eight‐site NMR spectra have been analysed and the barriers to rotation around the different bonds have been evaluated by a complete line shape treatment based on the Bloch formalism. Assignment of sites to methyl groups has been made with the aid of aromatic solvent induced shifts and anisotropy effects.
Lanthanide‐induced shifts in proton NMR spectra—IV: Praseodymium‐induced shifts to lower applied fields and obscured chemical shifts from lanthanide‐induced shift (LIS) data
Authors: Hlubucek J. R. , Shapiro B. L. 
Published: May 2005

AbstractPraseodymium(III) tris(dipivalomethanato) [Pr(DPM)3] reduces the complex overlapping aromatic absorptions in the proton NMR spectrum of a monosubstituted naphthalene, cis‐3‐(1‐naphthyl)‐1,3,5,5‐tetramethlcyclohexan‐1‐ol(1) to a virtually first‐order pattern, whereas Eu(DPM)3 at the same and higher molar concentrations does not completely resolve the aromatic proton signals. Plots of the Pr(DPM)3‐induced shifts measured in carbon tetrachloride solution versus molar equivalents of Pr(DPM)3 added may be extrapolated to provide accurate chemical shifts in the absence of added lanthanide shift reagent (LSR). The qualitative conformational conclusions from the Pr(DPM)3 shifts agree with those from the Eu(DPM)3‐induced shifts, but there are detailed differences in the relative lanthanide‐induced shifts (LIS) for different proton types in the molecule.
14N and 35Cl NQR studies of organophosphorus compounds
Authors: Osokin D. J. , Safin I. A. , Nuretdinov I. A. 
Published: May 2005

Abstract14N and 35Cl NQR spectra have been investigated for 24 organophosphorus compounds using a pulse technique. The electron populations of the nitrogen lone pair orbital and the NP bond are calculated according to the Townes and Dailey method. The experimental data are interpreted assuming a partial double bond character of the NP bond due to the pπdπ interaction and pπσ conjugation of the lone pair electrons of the nitrogen atoms. The effect of the different nature of substituents X on the NP bond populations is observed in X  PRn (R2N)3‐n molecules (where X is O, S, Se, or lone pair electrons and n = 0, 1, 2). It can be seen from this dependence that the effective electronegativity of the phosphorus atom is largest in selenophosphoramidates and falls in the sequence PSe > PS > PO > P.
An NMR study of spatial arrangements in natural alkaloids—I: Indor spectra and conformations of pachycarpine (d‐sparteine), lupanine and 13‐hydroxylupanine
Authors: Sadykov A. S. , Kamayev F. G. , Korenevsky V. A. , Leon'ev V. B. , Ustynyuk Yu. A. 
Published: May 2005

AbstractThe INDOR homonuclear PMR spectra of three quinolizidine alkaloids—pachycarpine (d‐sparteine), lupanine and 13‐hydroxylupanine—have been studied. The molecular conformations including the boat‐structure of the ring C have been established.
Analyse des Effets de Substituant du Noyau Benzenique EN RMN du Fluor: Application aux Fluoro‐2 Alcools Phenylethyliques
Authors: Aranda G. , de Luze H. 
Published: May 2005

AbstractLes déplacements chimiques du fluor de différents phényls‐1 et 2 fluoro éthanols ont été mesurés; les valeurs obtenues ont été extrapolées à dilution infinie en soluté et référence interne. Les corrélations linéaires ou non, obtenues entre ces déplacements chimiques et les constantes de substituant σ donnent lieu à une discussion générale relative à la validité des relations d'enthalpie libre étendues aux données de la RMN; les limites et les possibilités de telles relations sont précisées.
Zur Kenntnis des Chinoiden Zustandes—XX:13CMR‐Untersuchungen an Cyclohexadienonen
Authors: Rieker Anton , Berger Stefan 
Published: May 2005

AbstractDie 13C‐chemischen Verschiebungen von 19 para‐und 5 ortho‐Cyclohexadienonen werden durch 13C‐Fourier‐Transform‐Spektroskopie ermittelt und zugeordnet. Der Substituenteneinfluß auf die chemische Verschiebung der Signale der Ringkohlenstoffatome wird diskutiert. Durch die Aufstellung von Regressionsgeraden wird gezeigt, daß die Resonanzlagen der olefinischen Ringatome und des allylischen C‐Atoms im para‐chinoliden Ring wechselseitig voneinander abhängen. Eine Korrelation zwischen 1H‐NMR‐ und 13C‐NMR‐Daten wird am Beispiel der Cyclohexadienone überprüft.