bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformation et spectrométrie de R.M.N.: II
Authors: Wylde Renée , Saeluzika Justin
Published: May 2005

Les quatre tétradeutério‐1,1,4,4 diméthylamino‐3 décalols‐2 trans ont été synthétisés. L'examen des spectres de RMN de ces composés permet de confirmer la conformation ‘chaise aplatie’ de l'isomère cis à groupement diméthylamino axial et hydroxyle équatorial, tandis que les autres d'ammonium quaternaires on note également une déformation dans le cas du composé diaxial, cette déformation est accentuée dans l'iodure d'ammonium quaternaire cis N(CH3)3a OHe, conduisant à la conformation ‘chaise croisée’.
Effects of some phosphorus substituents on the carbon‐13 chemical shifts of alkyl chains
Authors: Quin Louis D. , Gordon Michael D. , Lee Shin Ok
Published: May 2005

The carbon‐13 NMR spectra of 16 aliphatic phosphorus compounds with ‐PCl2, ‐P(OCH3)2, ‐P(CH3)2 or ‐PS(CH3)2 groups were determined and interpreted on the basis of the usual α, β‐deshielding and γ‐shielding effects. The α‐effects of all the groups were quite large (15 to 30 ppm), though the β‐effects were small (0 to 3 ppm). The γ‐effects were also small (0·2 to 1·6 ppm), but of significance in suggesting reduced steric compression relative to that found for methyl and most of the common organic functional groups. This may be attributed to the greater length of the CP bond. The phosphorus‐31 NMR spectra of these compounds also show the existence of interaction with γ‐carbons by exhibiting small additive upfield shifts.
Nuclear magnetic resonance studies of internal rotation. V—Rotational barriers of acetylenic amides
Authors: Spassov S. L. , Dimitrov V. S. , Agova M. , Kantschovska‐Dimicoli I. , Todorova‐Momcheva R.
Published: May 2005

The rotational barriers about the CN bond of the N,N‐dimethylamides of propiolic, methylpropiolic and phenylpropiolic acids have been determined by the iterative total line shape nuclear magnetic resonance method.
Effects of methyl substituents on the proton chemical shifts in the NMR spectra of the twenty methyl and ethyl substituted hydrazines. Electronegativity values for hydrazyl groups
Authors: Condon F. E.
Published: May 2005

The CH proton NMR spectra of the twenty conceivable methyl and ethyl substituted hydrazines are presented and analyzed with respect to effects on chemical shifts of the CH protons caused by replacement of hydrogen by methyl and ethyl groups on the CNNC chain. Thirteen different methyl substituent effects and six different ethyl substituent effects are identified and evaluated. Most of the effects are shielding and in accordance with an electron‐releasing inductive effect of alkyl groups. A deshielding effect (the ‘CC bond effect’) is observed when a methyl group replaces the hydrogen on the carbon bearing the hydrogen in focus and primary hydrogen on the carbon bearing the hydrogen in focus and primary hydrogens become secondary, as observed in other systems. On the basis of their effects on the chemical shifts of methyl protons in CH3X, eighteen different hydrazyl groups (× = NR1NR2R3) fall into three classes: I (R1 = H; R2, R3 = H or alkyl); II (R1 = alkyl; R2 and/or R3 = H); III (R1, R2 and R3 = alkyl), with slightly different electronegativities: 2·94, 2·83 and 2·74, respectively.
13C nuclear magnetic resonance spectra of arylthallium(III) bis(trifluoroacetates)
Authors: Ernst Ludger
Published: May 2005

13C chemical shifts and 13C205Tl spin–spin coupling constants are reported for phenylthallium(III) bis(trifluoroacetate) and some of its mono‐ and dimethyl derivatives. The signs of nJ(13C, 205Tl) relative to n+1J(1H, 205Tl) are determined by offresonance decoupling of protons.
The temperature dependence of the 13C nuclear magnetic resonance spectra of porphyrins
Authors: Lincoln David N. , Wray Victor
Published: May 2005

The high temperature 13C NMR spectra of the methyl esters of deuteroporphyrin‐IX and protoporphyrin‐IX, and octaethylporphyrin show sharp discrete signals for the inner macrocycle carbon resonances. The temperature dependence of these shifts is discussed.
Applications of 1,4‐addition of grignard reagents to α,β‐unsaturated acid derivatives. III—configuration studies of α,β‐diaryl‐α,β‐dialkylpropionitriles
Authors: Wawzonek Stanley , Smolin Edwin M. , Durham Judith E.
Published: May 2005

The configuration of twenty‐four different α,β‐diaryl‐α,β‐dialkylpropionitriles has been determined using nuclear magnetic resonance spectra. The erythro form showed greater deshielding of the methine hydrogen and alkyl groups in its spectra than the corresponding threo isomer. The former, however, showed less deshielding of the aryl groups than the threo isomer. Infrared spectra were not suitable for assignments of configuration.
NMR spectra of molecules oriented in a lyotropic mesophase. III—The Spectrum of γ‐Hydroxypyridine
Authors: Khetrapal C. L. , Kunwar A. C. , Patankar A. V.
Published: May 2005

Analysis of the 1H NMR spectrum of γ‐hydroxypyridine dissolved in the lyotropic mesophase formed by a 14 : 1 : 1 : 20 mixture (by weight) of sodium dodecyl sulphate, decanol, sodium sulphate and D2O provides all the spectral parameters with reasonable precision. The chemical shift, the indirect and the direct proton–proton coupling constants are derived. The direct dipolar couplings thus determined are utilised to obtain the relative interproton distances. Information about the molecular orientation and the solvent solute interactions is deduced.
19F‐und 1H‐NMR‐spektroskopische Untersuchungen an Hexafluoraceton‐halbacetalen von Pyrimidin‐nucleosiden
Authors: Regel Walter , Stengele Eberhard
Published: May 2005

Die Umsetzung der OH‐Gruppen von Pyrimidin‐nucleosiden mit Hexafluoraceton führt quantitativ zu Halbacetalen, deren 19F‐NMR‐Spektren eine eindeutige Charakterisierung erlauben und z.B. Aussagen über den selektiven Einbau von Schutzgruppen ermöglichen. Die gegenüber den Ausgangs‐verbindungen verbesserte Löslichkeit der Halbacetale in vielen organischen Lösungsmitteln erweist sich auch für die Protonen‐resonanzspektroskopie als wesentlicher Vorteil.
The effect of the structure of substituted phenylphosphonic difluorides on their 19F and 31P NMR spectral parameters
Authors: Szafraniec Linda L.
Published: May 2005

The 19F and 31P NMR spectral parameters of a series of meta and para substituted phenylphosphonic difluorides were found to be linearly related to the substituent parameters: the phosphorus chemical shifts correlated with Hammett's σ constant, the fluorine chemical shifts with Taft's σR parameter and the phosphorus–fluorine coupling constants with σ+.
The structure of 1,6,6aλ4‐trithiapentalene and substituted 1,6,6aλ4‐trithiapentalenes studied by means of NMR spectroscopy
Authors: Pedersen Carl Th. , Schaumburg Kjeld
Published: May 2005

13C NMR spectra of unsubstituted 1,6,6aλ4‐trithiapentalene and a series of methyl and phenyl substituted 1,6,6aλ4‐trithiapentalenes have been recorded. The spectra have been assigned by comparison with 1H NMR data based on coupling constants from undecoupled spectra. From the chemical shift of C‐3a it is concluded that the double bond character of the C‐3a—S‐6a is low. The relaxation times for C‐2 and C‐3 only show small differences; this seems not to be in favour of a fast interconversion between two thiocarbonyl forms. The NMR data obtained seem thus to be in accordance with a bicyclic naphthalene‐like structure with ten delocalised π‐electrons.
1,2‐oxazine chemistry. V—vicinal, allylic and homoallylic coupling constants in the 3,6‐dihydro‐1,2‐oxazine ring
Authors: Riddell F. G. , Labaziewicz H.
Published: May 2005

The 1H NMR spectra of thirteen dihydro‐1,2‐oxazine derivatives are reported. Spin decoupling allows analysis of the spectra, features of which include homoallylic couplings of +2 to +2·5 Hz, allylic couplings of −1·5 to −1·7 Hz and vicinal couplings across sp2 to sp3 carbon–carbon bonds of +2·9 to +3·7 Hz.
Etude structurale de la bipyrimidine par RMN en phase nématique
Authors: Courtieu J. , Gounelle Y. , Duret C. , Gonord P. , Kan S. K.
Published: May 2005

Le spectre de RMN obtenu à 240 MHz pour la bipyrimidine orientée dans un solvant nématique p‐métoxybenzylidène p‐n‐butyl aniline est analysé. La distance entre les hydrogènes en position para est déterminée. La barrière de potentiel s'opposant à la libre rotation autour de la liaison centrale CC est étudiée. Un excellent accord est obtenu entre spectre calculé et spectre expérimental lorsqu'on utilise une fonction potentielle V(ϕ) = 1/2 ΣNVn (1 ‐ cosn ϕ) avec V1 = V2 = V3 = 0 cal mol−1 et V4 = 500 cal mol−1.
Nitrogen‐15 magnetic resonance spectroscopy XVI—natural‐abundance spectra of aromatic amines
Authors: Lichter Robert L. , Roberts John D.
Published: May 2005

The 15N chemical shifts of aniline, the toluidines, xylidines, and several halogen and oxygen substituted anilines have been measured at the natural abundance level of 15N. Substituent parameters obtained by multiple regression analysis show that the methyl group induces comparable upfield shifts at the ortho and para positions (2·37 and 2·55 ppm/methyl, respectively) and a small (0·77 ppm/methyl) upfield shift at the meta position. The chemical shifts correlate reasonably well with 19F shifts of similarly substituted fluorobenzenes, with C‐1 of the anilines themselves and with Hammett sigma values. While the shifts of C‐methyl substituted anilines do not correlate with the methyl resonances of corresponding polymethylbenzenes, those of the halo‐ and alkoxyanilines show a reasonable parallelism with corresponding 13C‐methyl shifts. The results are interpreted in terms of possible modes of transmission of electron density in an alternating and additive manner through the sigma framework.
The 1H NMR spectra of some norbornene derivatives, a LIS study
Authors: Abraham Raymond J. , Coppell Steven M. , Ramage Robert
Published: May 2005

The 1H NMR spectra of 2‐exo‐hydroxymethyl‐3‐endo‐methylnorbornene and the corresponding 2‐endo‐3‐exo isomer have been completely assigned with the aid of lanthanide reagents. This enabled a full analysis of the unusual spectrum of 2‐exo‐hydroxy‐methyl‐3‐endo‐methylnorbornene to be undertaken, confirming the proposed structure. The ΔEu values for 2‐exo‐hydroxymethyl‐3‐endo‐methylnorbornene and the 2‐endo‐3‐exo‐isomer have been used to test the effect of rotational averaging on the calculated pseudo contact shifts. Good agreement is obtained for a dynamic model in which the Eu atom exchanges between two sites on the oxygen atom of the OH bond, and in which the rotational equilibrium about the CHCH2OH bond is explicitly considered.
ESR spectrum of the radical anion of bicyclo[3.2.2]nona‐3,6,8‐triene‐2‐one
Authors: Gerson F. , Moshuk G. , Wydler Ch. , Goldstein M. J.
Published: May 2005

The radical anion of bicyclo[3.2.2]nona‐3,6,8‐triene‐2‐one has been characterised by ESR spectroscopy.
Complexation du trichlorure d'aluminium par la triméthylphosphine et la diméthylphénylphosphine: Etude RMN
Authors: Laussac J.‐P. , Laurent J.‐P. , Commenges G.
Published: May 2005

Les résultats de l'étude par résonance magnétique nucléaire des systèmes R3P/AlCl3 [avec R3 = (CH3)3 et (CH3)2 (C6H5)] ne peuvent ětre interprétés qu'en admettant l'existence, en solution et à 306 K, d'échanges rapides intéressant les complexes R3PAlCl3 et (R3P)2AlCl3 ainsi que la phosphine libre. Des expériences à basse température (173 K) confirment cette hypothèse et établissent définitivement l'existence des composés 2/1.
Etude par RMN d'une inversion de cycle de quelques benzodiazépinones
Authors: Sarrazin M. , Bourdeaux‐Pontier M. , Briand C. , Vincent E.‐J.
Published: May 2005

Les modifications, en fonction de la température, des spectres RMN de cinq benzodiazépinones permettent de mettre en évidence un équilibre entre deux formes pseudo‐bateaux du cycle à sept liaisons. Les auteurs calculent les paramétres d'activation et la constante de vitesse d'inversion et discutent le rǒle des substituants.
tert‐Butyl 7‐cycloheptatrienylperacetate: The proton NMR spectrum and conformational analysis
Authors: Jurch G. R. , Johnston M. D.
Published: May 2005

The proton magnetic resonance spectrum of tert‐butyl 7‐cycloheptatrienylperacetate has been analyzed with the aid of the lanthanide shift reagents, Eu(fod)3 Yb(fod)3. Observation of the lanthanide‐induced shifts showed, in conjunction with variable temperature studies establishing the conformational purity of the cycloheptatrienyl ring, that the peracetate substituent has a definite equatorial preference.
13C NMR study of the enol forms of β‐diketones
Authors: Shapet'ko N. N. , Berestova S. S. , Lukovkin G. M. , Bogachev Yu. S.
Published: May 2005

Carbon‐13 NMR spectra of a series of β‐diketones in the enol form with various β‐substituents have been studied. An additive influence of the β‐substituents on the chemical shifts of the carbon atoms in the hydrogen bonded chelate ring has been found. It is shown that the α‐ and β‐carbon chemical shifts can be calculated by means of a set of increments for arbitrary combinations of the X and Y substituents. Analysis of the experimental data enables the conclusions to be drawn that enol–enolic tautomerism with different populations of the forms (A) and (B) is absent in β‐diketones and that the carbon chemical shift changes are caused by electron density redistribution in the hydrogen bonded chelate ring (C).
Lanthanide‐induced shifts of diastereotopic groups
Authors: Bell Harold M.
Published: May 2005

The chemical shift differences of diastereotopic protons in aliphatic acyclic alcohols, mostly of the type RCH2CR′R″(CH2)nOH, have been investigated. Fairly small amounts of Eu(dpm)3 cause the spectra of these materials to simplify dramatically; indeed, even diastereotopic protons rather far removed form the hydroxyl group give discrete signals in the presence of the shift reagent. Large shift differences were realized in the γ‐protons (n = 1) and the δ‐protons (n = 2), particularly if R is bulky and R' and R″ have different steric requirements. Semi‐quantitative conformational preferences can be determined from the data obtained.
An investigation of contributions to carbon‐13 spin‐lattice relaxtion in amino acids and peptide hormones
Authors: Cutnell J. D. , Glasel Jay A. , Hruby V. J.
Published: May 2005

Carbon‐13 spin‐lattice relaxation times have been measured in glycine and the tripeptide pro‐leu‐gly‐NH2. These times are compared with those measured in the same compounds where the glycine α‐carbon has been deuterated. In this manner evidence is obtained which indicates that mechanisms other than dipolar interactions with covalently bonded protons may contribute to carbon‐13 spin‐lattice relaxation. The effect of these additional mechanisms is found to be non‐negligible for the carbonyl carbon of glycine and the glycine α‐carbon of the tripeptide. The implication of these findings for deducing motional information from carbon‐13 relaxation measurements is briefly discussed.
Beziehungen zwischen chemischer Verschiebung (19F und 13C) und Ladungsdichte: III
Authors: Sterk Heinz , Fabian Walter
Published: May 2005

Der diamagnetische und paramagnetische Term der chemischen Verschiebung wird durch semiempirische CNDO/II Ladungsdichte‐und Bindungsordnungswerte ausgedrückt. Es wird untersucht ob ein linear funktionaler Zusammenhang zwischen den berechneten Termen und der chemischen Verschiebung von 19F‐ und 13C‐Atomen besteht. In Form einer linearen Regression werden eine Reihe unterschiedlicher Ansätze–unter Berücksichtigung von s̀dia sowie s̀dia + s̀para—untersucht. Es zeigt sich, daß die Beziehung δA = a + bqA + cQAB + dqAπQAB den kleinsten mittleren Fehler aufweist.
Conformational analysis. XIII—A 300 MHz 1H NMR study of 2‐methyl‐, 2‐phenyl‐, 2‐(2‐chlorophenyl)‐and 2‐(4‐chlorophenyl)‐oxetanes
Authors: Pihlaja Kalevi , Jokisaari Jukka , Olavi P. , Virtanen I. , Ruotsalainen Heikki , Anteunis Marc
Published: May 2005

The 300 MHz spectra of 2‐methyl‐, 2‐phenyl‐, 2‐(2‐chlorophenyl)‐ and 2‐(4‐chlorophenyl)‐oxetanes were recorded in CCl4 and C6D6. The chemical shifts and the proton‐proton coupling constants were solved through iterative calculations. The results were discussed in the light of structural factors and theoretical calculations. The average angle of pucker for the oxetane ring was estimated at c. 5°, in fair agreement with the value of 3·3° derived from a microwave study.
Hétérocycles contenant du phosphore. XXIV—Etude par RMN du proton de l'oxo‐2 phénoxy‐2 diphényl‐6,6 oxazaphosphorinane‐1,3,2 et de l'oxo‐2 phénoxy‐2 méthyl‐4 oxadiazaphosphorinane‐1,3,4,2
Authors: Arshinova Rausa , Kraemer Raymond , Majoral Jean‐Pierre , Navech Jacques
Published: May 2005

Deux hétérocycles phosphorés sont étudiés au moyen de la RMN du proton et de l'infrarouge. La conformation du cycle est précisée et l'angle de torsion de la liaison C‐5—C‐6 est calculé pour l'un d'eux.
Verification of the correlation between geometric parameters of molecules and the parameters of their 1H NMR spectra
Authors: Vorontsova L. G. , Bochkov A. F.
Published: May 2005

The dihedral and bond direction angles between all pairs of vicinal protons of the arabinofuranose residue were calculated from the coordinatees of the hydrogen atoms found by an X‐ray study of 3‐O‐acetyl‐β‐L‐arabinofuranose 1,2,5‐orthobenzoate. The values found were compared with those calculated with the help of correlation equations previously proposed by Karplus and recently by the authors, linking the values of those angles with the spin‐spin coupling constants of vicinal protons [3J(H,H′)]. It has been found that the best agreement between the angles found crystallographically and calculated from the 1H NMR data can be achieved using the equation which includes bond direction angles and the sum of the chemical shifts of the protons involved.
Solvent effects of pyridine on the NMR spectra of carboxylic acids. I—study of the acrylic, trans‐crotonic and 3‐butenoic acids
Authors: Paasivirta Jaakko , Kolehmainen Erkki
Published: May 2005

Proton magnetic resonance spectral parameters of acrylic, trans‐crotonic and 3‐butenoic acids, their methyl esters and the corresponding alcohols (COOH substituted by CH2OH) have been measured for 5% (w/v) solutions in carbon tetrachloride and in pyridine‐d5 at 33·5 °C. The total solvent effect of pyridine on the shifts of the skeleton protons of the acid was found to consist of three different effects independently measured from the reference samples.
Carbon‐13 chemical shifts and 13C15N coupling constants of 3,4‐dihydroisoquinoline‐15N, its 15N‐oxide and their conjugate acids
Authors: Christl Manfred
Published: May 2005

On protonation of 3,4‐dihydroisoquinoline‐15N 1J(13C—1, 15N) is increased by a factor of five and 1J(13C—3, 15N) changes its sign, while on protonation of 3,4‐dihydroisoquinoline‐15N‐oxide the coupling constants, including the relatively large 1J(13C—1, 15N), remain practically constant, although significant alterations of the 13C chemical shifts take place.
Carbon‐13 NMR Spectra of some aryl substituted ferrocenes
Authors: Gronowitz S. , Johnson I. , Maholanyiova A. , Toma S. , Solcániová E.
Published: May 2005

The carbon‐13 spectra of some para and meta substituted phenylferrocenes have been analysed. The substituent‐caused shifts are discussed and compared with similarly substituted biphenyls. Correlations with Hammett parameters and with the reactivity parameters of Swain and Lupton have been attempted.
NMR study of organosilicon compounds. III—Silicon‐29, nitrogen‐14, carbon‐13 and proton NMR spectra of silylakylamines
Authors: Schraml J. , Nguyen‐Duc‐Chuy  , Chvalovský V. , Mägi M. , Lippmaa E.
Published: May 2005

29Si, 14N 13C and 1H NMR data are presented for a series of homologous (methylethoxysilyl)alkylamines of the type (CH3)3−n(C2H5O)nSi(CH2)mNH2(n=o to 3; m = 1 to 4). The measured 13C and 1H chemical shifts correlate with the total net charges QA on the corressponding atoms, estimated by the Del Re method. 14N and 29Si chemical shifts which do not show simple linear relationships to the charges are found to correlate with the relative basicities of the compounds. The influence of the remote substituent (NH2 and others) on the 29Si chemical shifts is shown to depend on the number and nature of substituents directly on the silicon atom. Argyments for d‐orbital participation in the SiO bounds are given. The chemical shifts of 29Si, 14N and 13C nuclei are not consistent with the fromation of intramolecular ‘long bonds’ between the solicon and nitrogen atoms in aliphatic silymethylamines.
1H and 13C NMR study of α‐acetylenic PIII and PIV derivatives. Signs and magnitudes of J(PC) and J(PH)
Authors: Lequan R.‐M. , Pouet M.‐J. , Simonnin M.‐P.
Published: May 2005

All J(PH) and J(PC) values, including signs, have been obtained in acetylenic and propynylic phosphorus derivatives, R2P(X)CCH and R2P(X)CCCH3 (X  oxygen, lone pair and R  C6H5, N(CH3)2, OC2H5, N(C6H5)2, Cl) from 1H and 13C NMR spectra. In PIV derivatives the following signs are obtained: 1J(PC)+, 2J(PC)+, 3J(PC)+, 3J(PH)+, 4J(PH). Linear relations are observed between 1J(PC), 2J(PC) and 3J(PC) versus 3J(PH), indicating that these coupling constants are mainly dependent on the Fermi contact term, though the other terms of the Ramsey theory do not seem to be negligible for 1J(PC) and 2J(PC).

In PIII derivatives these signs are: 1J(PC)‐ and +, 2J(PC)+, 3J(PC)‐, 3J(PH)‐, 4J(PH)+. Only 3J(PC) and 3J(PH) reflect a small contribution of the Fermi contact term while in 1J(PC) and 2J(PC) this contribution seems to be negligible relative to the orbital and/or spin dipolar coupling mechanisms.
Carbon‐13 NMR study of enamines and enamino ketones. A direct observation of the conformation of the 2‐methylcyclohexanone enamine tautomers
Authors: Tourwé D. , Van Binst G. , De Graaf S. A. G. , Pandit U. K.
Published: May 2005

The carbon‐13 spectra of a series of cyclohexanone, cyclopentanone and 2‐methylcyclohexanone enamines are reported. The influence of the amino component was studied in a series of enamino ketones. The spectra reflect the amount of p‐π overlap in the molecules and their conformation. Differences between 5‐and 6‐membered carbonyl components are evaluated.
Equilibre conformationnel du fluoro‐1 chloro‐2 cyclohexane cis
Authors: Baillif Patrick , Martin Jacques André
Published: May 2005

L'équilibre conformational et la cinétique de l'inversion du cycle sont étudiés essentiellement à partir de la forma de raie du fluor. Une nouvelle méthode de calcul des grandeurs thermodynamiques d'activation est présentée.
The 1H NMR spectra of quinoline, quinoline N‐oxide, the quinolinium ion and of their monomethyl derivatives
Authors: Barbieri Giorgio , Benassi Rois , Lazzeretti Paolo , Schenetti Luisa , Taddei Ferdinando
Published: May 2005

1H chemical shifts of quinoline, quinoline N‐oxide and the quinolinium ion were obtained by complete analysis of their NMR spectra and interpreted critically in an attempt to quantify the possible different effects acting on the shielding constant of protons in these systems. Semi‐empirical SCF calculations of electron charge densities and ring current contributions were also performed. It was found that the same effects that act on the shielding of protons directly bonded to the heterocyclic system also act, in an attenuated form, on the proton chemical shift of methyl groups in monomethyl derivatives. Vicinal coupling constants were rationalised in terms of π‐electron bond order and electro‐negativity of neighbouring atoms.
Effect of methyl substituents on the NMR spectra of aromatic protons of some nitrobenzene derivatives
Authors: Beltrame Paolo , Carniti Paolo , Lai Adolfo , Viglino Paolo
Published: May 2005

Proton NMR spectra were recorded and analysed for 1‐bromo‐4‐nitrobenzene, 2‐bromo‐5‐nitroluene, 3‐bromo‐6‐nitrotoluene and 2‐bromo‐5‐nitro‐p‐xylene, as well as for the corresponding compounds having p‐CH3C6H4S in place of Br. Chemical shifts and coupling constants generally agree with expected values; however, a deshielding effect of the methyl group on aromatic protons was observed in one case.
31P‐NMR‐Daten heterocyclischer phosphine. Diastereomerenzuordnung an 1,3‐Oxa‐, 1,3‐Aza‐ und 1,3‐thiaphospholanen
Authors: Zschunke A. , Meyer H. , Issleib K.
Published: May 2005

Die Diastereomeren von 16 1,3 Oxa‐, 1,3‐Aza‐und 1,3‐Thiophospholanen wurden mit Hilfe der Kopplungs‐konstanten 2J(PCH) und 3J(PCCH3), der Signalbreite der 31P‐Signale und der 1H‐chemischen Verschiebungen der CH3‐Gruppen zugeordnet. Es wird gezeigt, daß auch die 31P‐chemischen Verschiebungen eine Bestimmung der relativen Konfiguration dieser Verbindungen gestatten.
Proton magnetic resonance studies of compounds with bridgehead nitrogen: XXVIII—Stereochemical studies with perhydropyrido[1,2‐c] [1,6,3]dioxazocines and 2‐alkylperhydropyrido[1,2‐c] [1,3,6]oxdiazocines
Authors: Crabb Trevor A. , Jackson Graham C.
Published: May 2005

A series of perhydropyrido[1,2‐c][1,6,3]dioxazocines and 2‐alkylperhydropyrido[1,2‐c][1,3,6]oxdiazocines have been prepared. 6‐p‐Nitrophenyl‐3,4‐dimethylperhydropyrido[1,2‐c][1,6,3]‐dioxazodioxazocine is shown to adopt the cis fused ring conformation in solution with the nitrogen lone pair axial with respect to the piperidine ring. The 2‐alkylperhydropyrido[1,2‐c][1,3,6]oxdiazocines adopt a similar cis fused ring conformation and with increasing steric requirement of the 2‐alkyl substituent the 8‐membered ring increasingly favours the chair‐chair conformation, rather than the chair–boat conformation favoured by the 2‐methyl substituted compound.
Coupling constants in N‐substituted pyridines and their relation with electronegativity
Authors: Katritzky Alan R. , Kinns Michael , Lunt Edward
Published: May 2005

The coupling constants obtained from the complete spectral analysis of series of 1‐ and 3‐substituted pyridine N‐imides are related linearly to the electronegativities of the substituent atoms. The main conclusions of the papers by Cox, Castellano and Sun, and Castellano and Kostelnik are substantiated. The inductive effects of the first atoms of the substituents largely determine the coupling between protons in the ring system; delocalisation of π‐electrons in the ring produces a much smaller effect.
Quantitative analysis by nuclear magnetic resonance with fourier transformation: I—Proton case
Authors: Thiault B. , Mersseman M.
Published: May 2005

For quantitative analysis by NMR spectroscopy with Fourier transform, the usual experimental conditions have to be partly modified. Careful regulation of the delays between the different phases of the process is particularly important. The filters of the spectrometer and the calculations on the free induction decay are important causes of error. Precise results are given.
Etude par Résonance Magnétique Nucléaire du 13C des chlorhydrates de‐N‐(phényl‐1 cyclohexyl) piperidines.
Authors: Geneste P. , Kamenka J. M.
Published: May 2005

L'attribution des signaux de RMN du 13C de la N‐(phényl‐1 cyclohexyl) pipéridine et de quelques dérivés 4‐substitués, sous forme de chlorhydrates dans H2O et CDCl3, a permis une étude conformationnelle. Celle‐ci confirme la plus grande stabilité des composés dont le groupe pipéridinium est équatorial. Certaines particularités dans les glissements chimiques observés paraissent attribuables à des déformations du système cyclohexanique, étroitement liées au phénomène de solvatation.
A proton magnetic resonance study of isomeric alkylidencyanoesters
Authors: Giralt Ernest , López Francisco , Alvarez Mercedes
Published: May 2005

Ethyl 2‐cyano‐3‐methyl‐4‐phenyl‐2‐pentenoate was obtained as a mixture of two geometric isomers. An aromatic solvent induced shift experiment and calculations of the difference in the chemical shifts of methyl protons linked to the double bond lead to the assignation of the geometry of both isomers.
NMR spectra of seleninium and 1‐ and 2‐benzoseleninium cations
Authors: Boccuzzi Flora Catti , Fochi Rita
Published: May 2005

The analysis of the NMR spectra of seleninium and 1‐and 2‐benzoseleninium cations, recorded in deuterotrifluoroacetic acid, is reported. The effects of condensation on the spectral parameters of the protons of the seleninium ring were examined with particular reference to the shift to higher values of δ: this was consistent with the q values calculated by the HMO method. The 3J(HH) and 4J(HH) variations, including an interesting variation regarding the through‐selenium 4J coupling, are also discussed.
Spectre RMN 1H et 13C de tous les mono‐ et diacétoxynaphtalènes. Increments de déplacement chimique pour le proton et le carbone‐13. Cas de quelques autres dérivés du naphtalène
Authors: Granger P. , Maugras M.
Published: May 2005

L'étude complète de cette série permet de justifier l'emploi des systèmes d'incréments pour l'identification des raies de résonance du proton et du carbone 13. Ces incréments peuvent être obtenus en première approximation par l'étude des dérivés monosubstitués ou par comparaison avec les dérivés du benzène.
The 14N NMR linewidth versus pH profiles for several amino acids
Authors: Cohen E. A. , Shiller A. M. , Chan S. I. , Manatt S. L.
Published: May 2005

A spectrometer for recording 14N NMR spectra is described. The 14N NMR linewidth versus pH dependences of several amino acids and related molecules are presented. It appears that the linewidth pH profile of each amino acid is unique. Linewidth minima occur between pH 6 and 8. A discussion on how 14N NMR linewidths of amino acids might give information on weak association is given.
Group IV organometal derivatives of pyridine. I—A 1H and 13C NMR investigation of trialkylmetal derivatives of pyridine
Authors: Mitchell Terence N.
Published: May 2005

The proton and carbon‐13 NMR spectra of thirteen trialkylmetal derivatives of pyridine, several of which were previously unknown, have been recorded and analysed. The proton NMR spectra show variations in proton chemical shifts but not in proton‐proton coupling constants when the metal substituent is changed; the ring proton‐metal coupling constants nJ(MH) in the tin and lead derivatives correspond closely with the corresponding proton‐proton couplings nJ(HH) in pyridine. The carbon‐13 chemical shifts of the carbons bound to the metal can apparently be correlated with the electron‐donating ability of the trialkylmetal group. In the trimethylstannylpyridines the value of 1J(SnCring) varies greatly with the position of the Me3Sn group.
Double inversion de fréquences de protons méthyléniques par interaction 1‐3 syn‐diaxiales. Mise en évidence par RMN haute résolution
Authors: Grenier‐Loustalot M. F. , Lectard A. , Metras F.
Published: May 2005

L'étude par RMN à haut champ de deux trihalogéno‐2,3,6 méthyl‐2 cyclohexanones nous a permis de mettre en évidence une double inversion de fréquences de protons méthyléniques par interaction 1‐3 syn‐diaxiales.
A computer system for structural identification of organic compounds from 13C NMR data
Authors: Schwarzenbach R. , Meili J. , Könitzer H. , Clerc J. T.
Published: May 2005

A computerised library search system for 13C NMR data is described. Given the spectral data of an unknown compound, the system will retrieve from the library those reference compounds exhibiting similar spectra. For comparison the spectral data are converted into a binary code, designed to reflect the underlying structure rather than exact values for chemical shifts. Thus, the ability of the system to retrieve compounds similar to the unknown (as opposed to identical) is greatly enhanced. A sophisticated search strategy adapting itself automatically to the problem at hand makes the system highly efficient.
Concerning some unusual trimethylsilyl proton chemical shifts
Authors: Shapiro B. L. , Proulx T. W.
Published: May 2005

Proton and 13C NMR data are presented for six different compounds containing the fragment C6H5CCH2SiMe3. In a number of instances it was observed that, in the 1H NMR spectrum, the SiMe3 groups had a chemical shift significantly upfield from internal tetramethylsilane (δ = −0·14 to −0·36). These unexpected upfield chemical shifts of the SiMe3 groups are suggested to result from the predominance, on a time averaged basis, of conformations which place the methyl groups attached to silicon in the face of an aromatic ring. The preference for such conformations is, in turn, the result of rotational preferences exhibited by the ‘flat’ aromatic ring. These results suggest that conformational analysis of systems containing a phenyl ring should take more explicit account of the fact that the preferred orientation of this phenyl ring can have a profound influence on the conformation adopted by the remainder of the molecule. In addition, the preferred conformation of the phenyl ring can have a significant effect upon the observed 1H NMR chemical shifts, while the 13C chemical shifts are relatively insensitive to conformational factors and can be explained by well‐known substituent effects previously delineated for all‐carbon systems.
Complete analysis of the 1H NMR spectra of acetylated glycals—a conformational study
Authors: Rico M. , Santoro J.
Published: May 2005

The complete analysis of the 1H NMR spectra of the six acetylated glycals as well as that of tetra‐O‐acetyl‐2‐hydroxy‐D‐glucal has been carried out. The conformation of these compounds, as determined from the proton couplings (±0.05Hz) obtained, has been interpreted in terms of a rapid interconversion equilibrium between the two possible dihydropyran half‐chair conformations. A computer treatment of all observed couplings has been carried out to obtain optimized values for the populations and couplings characteristic of the two alternative half‐chair conformations. The rotamer populations of the acetoxy–methyl group are discussed on the basis of the measured 5J16 and 5J36 couplings.
Etude des formes fermées et ouvertes de spiropyrannes benzothiazoliniques en RMN 13C et 1H par transformée de Fourier
Authors: Samat A. M. , Guglielmetti R. J. , Martin G. J.
Published: May 2005

Une étude comparative en RMN 13C et 1H par transformée de Fourier a été réalisée sur des spiropyrannes, des mérocyanines et des photomérocyanines hautement stabilisées thermiquement, en série benzothiazolinique. Les résultats obtenus mettent en évidence la polarité des formes ouvertes (mérocyanines et photomérocyanines stables), de façon générale leur configuration trans, la répartition alternée des densités électroniques sur le pont diméthinique reliant les parties ‘benzothiazolinique’ et ‘phénolate’ de ces molécules, l'existence d'une configuration privilégiée dans le cas de photomérocyanines où un groupement alkoxy ou aryloxy occupe la position 3.
Carbon‐13 chemical shifts of bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane derivatives
Authors: Lippmaa E. , Pehk T. , Belikova N. A. , Bobyleva A. A. , Kalinichenko A. N. , Ordubadi M. D. , Platé A. F.
Published: May 2005

13C chemical shifts of more than fifty bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane derivatives (hydrocarbons, alcohols, ketones and esters) have been determined. The usefulness of ethyl derivatives for the assignment of close 13C chemical shifts in bicyclic methyl derivatives is shown both for the bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane series. Comparison of substituent effects on α‐, β‐, γ‐ and δ‐carbons in both series of compounds shows remarkable differences in steric interactions. In contrast to the rigid bicyclo[2.2.1]heptane system, both chair and boat conformations can be predominant in the bicyclo[3.2.1]octane series with the conformationally flexible 6‐membered ring.
13C NMR study of N‐unsubstituted aziridines: I—steric effects, pseudoconjugation
Authors: Mison P. , Chaabouni R. , Diab Y. , Martino R. , Lopez A. , Lattes A. , Wehrli F. W. , Wirthlin T.
Published: May 2005

13C chemical shifts for twenty‐nine alkyl and phenyl substituted N‐unsubstituted aziridines have been measured. Additivity parameters for methyl, phenyl and aziridyl carbons have been derived with the aim of testing the consistency of the assignments made on the basis of chemical shift considerations and off‐resonance decoupling information. The observed chemical shifts are discussed in terms of steric and pseudoconjugation effects.
Hindered rotation and electronic distribution in thiocarbamates
Authors: El Migirab Saadeddin , Jadot Joseph , Laszlo Pierre , Stockis Armel
Published: May 2005

We wish to report here the isolation of methyl N‐(p‐methoxybenzyl)thiocarbamate, a natural product extracted from Pentadiplandra brazzena Bailli, and the synthesis of its homologue, benzyl N‐(2‐phenylethyl)thiocarbamate. The barrier to internal rotation calculated from a complete lineshape analysis of the temperature dependent 1H n.m.r. spectra is discussed. The extent of delocalization on the three N, S and O substituents on the central trigonal carbon atom is gauged from a double labelling experiment.
Chemically‐induced dynamic nuclear polarisation. Photoreactions of organomercury compounds
Authors: de Kanter F. J. J.
Published: May 2005

The photolysis of symmetric and asymmetric organomercury compounds has been studied by CIDNP. No indications of the existence of RHg· radicals have been found. Depending on the solvent, reactions occur from excited states with different spin multiplicities.
Proton magnetic resonance spectra of monosubstituted naphthalenes
Authors: Lucchini Vittorio , Wells Peter R.
Published: May 2005

The chemical shifts and coupling constants for the ring protons of fourteen monosubstituted naphthalenes in carbon tetrachloride solution have been obtained by analysis and computer simulation of their 100 MHz magnetic resonance spectra. Studies at several concentrations have enabled shifts extrapolated to infinite dilution to be obtained and concentration effects arising from solute–solute interactions to be determined.
1H NMR spectra and structures of some bicyclic compounds oriented in nematic phases
Authors: Diehl P. , Zimmermann H.
Published: May 2005

The 1H n.m.r. spectra of 1,4,5‐triazanaphthalene, benzothiazole and quinoline oriented in nematic liquid crystalline phases have been analysed and the parameters used to determine the interproton distance ratios.
13C and 19F chemical shifts of bridgehead halogenated adamantanes
Authors: Perkins Robert R. , Pincock Richard E.
Published: May 2005

The 13C chemical shifts of the sixteen bridgehead substituted mono‐, di‐, tri‐ and tetrahaloadamantanes (halo = F, Cl, Br, I) and four mixed 1,3‐dihaloadamantanes are reported. The effect of bridgehead halogens on the shift values of carbons in β and δ positions is well correlated by the simple additivity relationship based on substituent shifts of 1‐monohaloadamantanes. A substituted α‐carbon is shifted upfield with an increase in the number of halogens at other bridgehead positions and this shift is relatively greater in the order F < Cl < Br < I. This observed upfield shift of α‐carbons is opposite to the downfield shift expected from additivity. An unsubstituted bridgehead γ‐carbon is moved to lower fields by one, two and three bromines (or iodines) at other bridge‐heads while, in contrast, a third fluorine weakly shields the remaining unsubstituted γ‐carbon. Some special noncumulative effects of halogens operating across the 1,3‐bridgehead positions of adamantane are indicated by the data. The 19F chemical shifts of 1‐fluoro‐, 1,3‐difluoro‐, 1,3,5‐trifluoro‐ and 1,3,5,7‐tetrafluoroadamantanes are contrary to expectations based on inductive effects in that they move progressively upfield. Other 1‐fluoroadamantanes with chloro, bromo, or methyl groups present also show substituent‐induced chemical shifts which shield the fluorine.
A 13C NMR study of actinomycin D and related model peptides
Authors: Booth H. , Mauger A. B. , Rzeszotarski W. J.
Published: May 2005

13C n.m.r. pulsed Fourier transform spectra were measured and interpreted for actinomycin D and for two related peptide derivatives: BOC‐Pro‐Sar‐OCH3 and BOC‐Sar‐Meval‐OCH3. Actinomycin D, specifically enriched with 13C in the chromophoric C‐methyl and in the peptide N‐methyl carbons, was produced biosynthetically. Enrichment of specific N‐methyl carbons in the model peptides was effected synthetically. Spectral assignments relied on the use of the enriched samples and particularly on off‐resonance and selective low power 1H decoupling experiments. Poor correlation was observed between some of the 13C chemical shifts in the model compounds and those of the analogous carbons in actinomycin D. Ten of our 13C assignments for actinomycin D differ from those published by Hollstein, Breitmaier and Jung.
13C n.m.r. spectra of some polychloroalkenes
Authors: Chukovskaya E. C. , Dostovalova V. I. , Vasil'eva T. T. , Freidlina R. Kh.
Published: May 2005

13C n.m.r. spectra have been measured for thirty‐two polychloroalkenes including (i) monosubstituted compounds CH2CHCClnH2−nX, where X stands for H, Cl, alkyl, and trisubstituted alkenes CCl2CHAlk, none of which form geometric isomers; (ii) disubstituted compounds RCHCHR′; (iii) and (iv) trisubstituted compounds of the types RCClCHR′ and CHClCClR, respectively. Compounds (ii) to (iv) represent either individual isomers or mixtures of the Z and E forms. In the case of compounds (ii) and (iii), the ordering of chemical shifts is δE > δZ for the sp2‐carbon atoms and δE < δz for the adjacent tetrahedral ones. On the contrary, the signals of the sp2‐carbon atoms of compounds (iv) obey the rule δE < δz. The effect of vinyl and allyl groups as substituents on the 13C chemical shifts of chlorine‐containing groups is discussed. The dependence of the sp2‐carbon spin–spin coupling constants J(13C1H) on the number of chlorinated substituents in the molecule is also considered.
19F n.m.r spectra of polyfluoroquinolines. Long range inter‐ring 19F19F coupling constants and 19F chemical shifts
Authors: Matthews R. S.
Published: May 2005

The signs and magnitudes of every fluorine–fluorine coupling constant in perfluoroquinoline (1), 2,4‐dichloropentafluoroquinoline (2) and 2‐bromohexafluoroquinoline (3) have been determined by 19F n.m.r. These provide an unambiguous assignment of the spectrum of the first compound and its derivatives. Inter‐ring fluorine–fluorine coupling constants were found to be positive over an odd number of bonds and negative over an even number of bonds, similar to that observed in proton–proton coupling constants in multicyclic systems.

The 19F chemical shifts of perfluoroquinoline and its protonated salt are reported and directly correlated with SCF MO calculated π‐electron densities at both fluorine and bonded carbon atoms.
1H‐NMR‐Spektroskopische Untersuchungen an isomeren Alkendiinen
Authors: Hiller A. , Kleinpeter E. , Schulze K.
Published: May 2005

Die 1H‐NMR‐Spektren einer Reihe aliphatisch und phenylsubstituierter Alkendiine werden vorgestellt und, unter Berücksichtigung einiger literaturbekannter Verbindungen, chemische Verschiebungen und Kopplungskonstanten diskutiert.

Die chemischen Verschiebungen der Protonen der untersuchten isomeren Alkendiine RCCCCCHCH2, RCHCHCCCCH und RCHCHCCCCCH3 (R = H, Alkyl, C6H5, C6H4OCH3‐p,) lassen sich hinsichtlich cis/trans‐Isomerie und Substitution an der Doppelbindung befriedigend mit elektronischen Effekten und molekularen Magnetfeldern der Mehrfachbindungen erklären. Die Kopplungs‐konstanten erweisen sich als kaum abhängig von der Substitution an der Doppelbindung. Über die Diacetylengruppierung hinweg können Kopplungen über maximal acht Bindungen beobachtet werden.
NMR studies of sulphur heterocycles: III—13C spectra of benzo[b]thiophene and the methylbenzo[b]thiophenes
Authors: Clark P. D. , Ewing D. F. , Scrowston R. M.
Published: May 2005

All carbon resonances in the title compounds have been unequivocably assigned. Steric effects in the peri substituted compounds have been compared with analogous effects in naphthalene and benzo[b]furan. The observed effects are not explained by current theory. Unusual deshielding steric shifts are observed at some carbons. Methyl substituent effects are not additive at any position in the sterically crowded 2,3‐disubstituted compounds.
Effects of molecular asymmetry on 13C chemical shifts in some O‐ and N‐glycidyl compounds
Authors: Everatt B. , Haines A. H. , Stark B. P.
Published: May 2005

In the 13C{1H} n.m.r. spectra of certain organic compounds containing two or three glycidyl (2,3‐epoxyprop‐1‐yl) groups, chemical shift nonequivalence has been observed, between diastereoisomers, for chemically similar carbon atoms in the glycidyl groups. Nonequivalence was only apparent when the glycidyl groups were linked through a single atom. In three derivatives of diglycidylaminobenzene, 13C chemical shift nonequivalence was also observed for aromatic carbon atoms ortho to the nitrogen substituent.
13C n.m.r. studies of organosilanes: II—substituent chemical shift parameters for alkoxysilanes
Authors: Rakita P. E. , Worsham L. S. , Srebro J. P.
Published: May 2005

The 13C n.m.r. spectra of forty alkoxysilanes of the general type XnSi(OR)4–n (X = CH3, C6H5, H; R = CH3, C2H5, n‐C3H7, i‐C3H7, n‐C4H9, i‐C4H9, s‐C4H9, n‐C5H11, CH(CH3)(C6H5), C6H5) have been recorded and assigned. The chemical shifts of the α‐carbon resonances of the alkoxy groups are shown to depend on both the nature of the alkoxy group and the number and type of substituents on the silicon. Regression analyses of the data give empirical substituent chemical shift (SCS) parameters for the silyl substituents. The β‐carbon resonances are shown to be dependent on the presence of the silyl group, but not the specific silyl substituents.
Proton n.m.r. spectra of furo[3,2‐c] and furo[2,3‐c]thiapyrylium cations, compared with their thieno homologues. Correlations between chemical shifts and charge densities from CNDO/2 and PPP calculations
Authors: Boccuzzi Flora Catti
Published: May 2005

Significant variations of thiapyrylium chemical shifts, by comparison with their thienohomologues, are shown by 1H n.m.r. spectra of furo[3,2‐c]thiapyrylium and furo[2,3‐c]thiapyrylium perchlorates. The observed changes can be ascribed to a different distribution of the electron charge (mainly caused by participation of the 3d orbitals of sulphur in the thienohomologues) and to a different contribution of the ring current; this is shown by MO calculations performed by the CNDO/2 and the coupled Hartree–Fock methods, respectively.
Determination of conformation of halomethyl ketones from the temperature dependence of Geminal H,H coupling constants
Authors: RamaRao M. , Bothner‐By A. A.
Published: May 2005

The temperature dependence of the geminal H,H coupling constant in solutions of α‐chloroacetophenone, α‐bromoacetophenone, 1‐bromo‐3‐chloro‐1‐phenylpropan‐2‐one and 1,3‐dibromo‐1‐phenylpropan‐2‐one has been determined at temperatures between 230 and 404 K. The values indicate that in the chloromethyl ketones the conformer with halogen and oxygen eclipsed is favored over that with hydrogen and oxygen eclipsed, while in the bromomethyl ketones the two conformers are of more nearly equal energy. The use of geminal coupling constants to indicate conformational preferences in substituted ketones appears promising.
Proton spin coupling constants in methylcyclopentadienes
Authors: Mstislavsky V. I. , Korenevsky V. A. , Sergeyev N. M. , Solkan V. N.
Published: May 2005

A detailed procedure for analysing the 1H n.m.r. spectra of two isomeric methylcyclopentadienes, two dimethylcyclopentadienes and 3‐methylindene is reported. Finite perturbation INDO calculations are used to discuss the conformational features of the long range proton coupling constants.
The dilution behaviour of chlorophyll derivatives possessing α‐hydroxyethyl groups
Authors: Brockmann Hans , Trowitzsch Wolfram , Wray Victor
Published: May 2005

The dilution behaviour of 2(R, S)‐α‐hydroxyethyl‐2‐desvinylpyromethylphaeophorbide a (1), observed by 1H n.m.r. spectroscopy, leads to the conclusion that the doubling of many of the lines in the spectra of 1 at high concentrations in CDCl3 arises from intermolecular diastereoisomerism caused by aggregate formation.