bluuebunny/crossref_metadata_2025 huggingface dataset:
Complete proton and carbon nuclear magnetic resonance spectral assignments of some morphinan‐6‐one alkaloids by two‐dimensional NMR techniques
Authors: Caldwell Gary W. , Gauthier A. Diane , Mills John E. , Greco Michael N.
Published: May 2005

The 1H (400 MHz) and carbon 13C (100 MHz) NMR peak assignments of two oxymorphone alkaloids including the free base and the hydrochloride (HCl) salt and four oxycodone alkaloids including the free base, the HCl salt, the N‐oxide and the methyl iodide quaternary salt were assigned using a variety of two‐dimensional NMR techniques. Proton coupling constants provide evidence that the cyclohexanone (D) and the piperidine (E) rings adopt slightly distorted chair conformations. Nuclear Overhauser enhancement difference experiments indicate that the conformation of the N‐methyl group is equatorial and the O‐methyl group prefers a cis orientation relative to C‐2. The minor component observed in aqueous 1H and 13C NMR spectra of each HCl salt and the N‐oxide is produced by the reaction of the alkaloid with water at the C‐6 carbonyl, forming a gem‐diol, and is not due to the presence of the axial isomer. The first complete solution and solid conformational analyses of oxycodone N‐oxide by NMR and x‐ray crystallography have been investigated. The data indicate that the C‐14‐OH proton is intramolecularly hydrogen bonded to the NO oxygen.
Heavy atom solid‐state NMR. Mercury‐199 spectral simulation and effects of off‐magic angle spinning
Authors: Groombridge Christopher J.
Published: May 2005

The effects of small deviations from the magic angle on 199Hg solid‐state NMR spectra with large chemical shift anisotropy are shown by computation and illustrated with spectra of mercury(II) acetate. These are shown to give the false appearance of multiple species, and place great importance on very precise angle setting (much better than ± 0.1°) for heavy atom solid‐state NMR. Chemical shift tensor principal components have been derived from spinning sideband analysis, and the difficulties of this are discussed; revised values for the anisotropy and asymmetry of mercury(II) acetate are −1732 ppm and 0.08, respectively. 199Hg spectra are also given for mercury(II) lactate and citrate.
Substituent‐induced chemical shifts (SCS) by the phenyl group in sterically congested styrene derivatives
Authors: Knorr Rudolf , Stephenson David S. , Böhrer Petra , Hoang Thi‐Phung
Published: May 2005

The two 13C NMR methyl signals of the sterically congested 9‐benzylidene‐1,8‐dimethylfluorene (1a) have the surprisingly small separation of only 0.37 ppm; for 9‐benzylidene‐2,7‐dimethylfluorene the corresponding methyl separation is 0.04 ppm. An alternative analysis of 1a with respect to 1,8‐dimethylfluorene shows that the perturbing syn‐phenyl substituent has caused a downfield ( + 0.47 ppm) 13C shift but an upfield 1H shift ( − 0.97 ppm) of the compressed 1‐CH3 group. For further comparisons, NMR assignments were also made for 2,7‐dimethylfluorene, 1,8‐dimethylfluoren‐9‐one and 2‐(1,1‐dimethylethyl)‐3,3‐dimethyl‐1‐phenylbut‐1‐ene.
Simplification of 13C NMR spectra by selective excitation of subspectra
Authors: Schraml Jan , Pelnař Jan , Blechta Vratislav
Published: May 2005

A new combination of 1D HOHAHA and INEPT pulse sequences is proposed and tested on an antibiotic, amikacin disulphate. The sequence provides 13C NMR spectra of chosen structural subunits and thus facilitates the NMR analysis of oligomers.
1H and 13C chemical shifts of (E)‐ and (Z)‐stilbenes and of phenanthrenes di‐substituted by oxygenated side‐chains
Authors: Touillaux R. , Weiler J. , Soumillion J.‐Ph. , Motte F.
Published: May 2005

The assignment of the 13C and 1H resonances of phenanthrenes and stilbenes di‐substituted with oxygenated side‐chains is presented based on chemical shifts, multiplicities and proton‐selective irradiation.
True spatial mapping of 14N by 3D NMR imaging
Authors: Kinchesh Paul , Randall Edward W. , Williams Steve C. R.
Published: May 2005

Three‐dimensional NMR imaging was used to create true maps of the 14N distribution in aqueous phantoms containing ammonium nitrate and sodium azide. The technique allowed for the creation of separate images from each nitrogen chemical environment and a total nitrogen image devoid of any appreciable artefacts.
Nuclear magnetic resonance study of sulphur diimides bearing the Di‐tert‐butylphosphinyl substituent—application of Hahn‐echo extended pulse sequences
Authors: Wrackmeyer Bernd , Gerstmann Silke , Herberhold Max
Published: May 2005

Sulphur diimides of the type BuP(NSN)R′ [R′ = PBu (1), But (2), SiMe3 (3), SiPh2Me (4), SiMe2But (5), SiPh2But (6), SiBuH (7), Si2Me5 (8), GeMe3 (9), SnMe3 (10), SnBu3 (11), SnPh3 (12)] and Bu(E)P(NSN)R′ [R′ = But, E = S, Se [2(S), 2(Se)]; R′ = SiPh2But, E = S, Se [6(S), 6(Se)]] were studied by solution‐state 15N and 31P NMR in order to obtain information on their preferred configuration in solution. Hahn‐echo extended (HEED) pulse sequences served for measuring coupling constants 1J(31P 15N) from 31P NMR spectra, giving at the same time isotope‐induced chemical shifts 1Δ 15/14N(31P) with 15N at natural abundance. Chemical shifts δ 15N are sensitive towards substituents in E‐ (deshielding) and Z‐positions (shielding). All NMR data indicate that most compounds are fluxional, at least at room temperature, with respect to interconversion of configurational isomers (E/E, E/Z, Z/E). The consistent NMR data suggest that the BuP group prefers the E‐position. Solid‐state 31P and 15N cross‐polarization magic angle spinning NMR spectra of 1 and 7 support the assumption of different structures in solution and in the solid state, in accord with the assumed fluxional behaviour in solution.
13C NMR assignments of 1‐oxaspiro[4.5]decan‐2‐ones and 1‐oxaspiro[4.5] decanes
Authors: Alonso Daniel , Font Josep , Ortuño Rosa M.
Published: May 2005

13C NMR studies of a series of lactones and ethers containing the spiro[4.5] decenering system were carried out. Complete 13C chemical shift assignments were achieved.
Heteronuclear long‐range coupling constant 4J(31P, C, S, C, 1H) in diethyl α‐methylthio‐substituted phosphonates and related compounds
Authors: Balczewski P.
Published: May 2005

The long‐range coupling constant 4J(31P, C, S, C, 1H) was measured in several diethyl α‐methylthio‐substituted phosphonates and their analogues. A dependence of the 4J coupling on the substituent electronegativity was observed.
Nitramino, NRNO2 (R = H, CH3), as a substituent. 13C and 15N NMR spectroscopic study of nitraminobenzenes and ‐pyridines
Authors: Kolehmainen Erkki , Laihia Katri , Kauppinen Reijo , Gawinecki Ryszard , Rasala Danuta
Published: May 2005

In order to clarify the special properties of the aryl‐bound nitramino substituent NRNO2 (R = H, CH3), 13C and 15N NMR spectra of six nitraminobenzenes and nine nitraminopyridines were measured in DMSO‐d6 and their chemical shifts assigned. 1H NMR chemical shifts and spin‐spin coupling constants of all the compounds were also determined. In contrast to the behaviour of nitropyridines or ‐benzenes studied previously, most of the present compounds gave very broad 17O NMR lines even at elevated temperatures and their 17O NMR data were not useful for any reliable conclusions.
NMR study of some dihydrobenzofuran lignans
Authors: Pieters Luc , De Bruyne Tess , De Groot Alex , Mei Gao , Dommisse Roger , Lemière Guy , Vlietinck Arnold
Published: May 2005

A detailed NMR analysis of 3′,4‐O‐dimethylcedrusin and 4‐O‐methylcedrusin using two‐dimensional COSY, HETCOR and long‐range HETCOR techniques showed that some 13C NMR spectral assignments reported previously for related dihydrobenzofuran lignans such as dihydrodehydrodiconiferyl alcohol and dihydrocarinatinol must be revised.
15N NMR spectra of carbolines
Authors: Markgraf J. Hodge , Richardson David P. , Livingston Robert C.
Published: May 2005

The 15N NMR spectra of α‐, β‐, γ‐ and δ‐carboline and a series of methyl, dihydro and tetrahydro derivatives are reported.
New bitter saponins from the bark of Colubrina elliptica: 1H and 13C assignments by 2D NMR spectroscopy
Authors: Tinto Winston F. , Reynolds William F. , Seaforth Compton E. , Mohammed Shaliza , Maxwell Anderson
Published: May 2005

Three new bitter saponins, designated mabioside A, B and C, were isolated from the bark of Colubrina elliptica and were determined to be 3‐O‐[α‐JL‐rhamnopyranosy]‐(1 → 6)‐β‐D‐glucopyranosyl‐15‐O‐[β‐D‐ glucopyranosyl] mabiogenin, 3‐O‐[α‐L‐rhamnopyranosy]‐(1 → 6)‐[β‐D‐glucopyranosyl‐(1 → 2)]‐β‐D‐glucopyranosyl}mabiogenin and 3‐O‐[α‐L‐rhamnopyranosyl‐(1 → 6)‐β‐D‐glucopyranosyl] mabiogenin, respectively. The structures were elucidated by using a combination of 2D NMR techniques (H‐H COSY, H‐H DQF‐COSY, RCT‐COSY, C‐H COSY, FLOCK, NOESY).
Assignments of the 1H and 13C NMR spectra of trans‐4‐hydroxy‐N‐9‐fluorenylmethoxycarbonyl‐L‐proline using one‐ and two‐dimensional NMR spectroscopy
Authors: Aksnes Dagfinn W. , Francis George W. , Papaioannou Dionissios
Published: May 2005

The 1H and 13C NMR spectra of trans‐4‐hydroxy‐N‐9‐fluorenylmethoxycarbonyl‐L‐proline show a 56:44 mixture of two conformers due to hindered rotation around the partial CN double bond. A combination of homo‐ and heteronuclear 1 D and 2D NMR techniques provided the assignments of the 1H and 13C resonances.
Application of two‐dimensional NMR to the structure determination of an unsymmetrical monosubstituted bisporphyrin
Authors: Sala R. Costa i , Latour J.‐M. , Bardet M.
Published: May 2005

The complete assignment of 1H and 13C data of an unsymmetrical monosubstitute bisporphyrin based on an extensive application of two‐dimensional 1H1H, 1H13C and 13C‐13C shift spectroscopy is described. The 1H1H shift correlation through dipolar interaction (2D NOESY) was essential to prove the connection of the alkyl fragments and to distinguish protons spatially close but belonging to different units. The additive structural increments method allowed the assignment of the quatenary carbons of tolyl residues.
NMR‐invisible nucleosides in adducts formed from carcinogenic nitrobenzo[a]pyrenes
Authors: Evans Frederick E. , Deck Joanna , Herreno‐Saenz Diogenes , Fu Peter P.
Published: May 2005

Anomalous 1H NMR spectra have been obtained for two related carcinogen‐nucleoside adducts in which a 1‐ or 3‐aminobenzo[a]pyrene ring is bound from its C‐6 position to the N−2 position of 2′‐deoxyguanosine. NOESY and COSY measurements at low temperature in methanol‐d4 revealed chemical exchange between at least two forms. Large chemical shift differences exist between subspectra for all corresponding protons of the nucleoside moiety, whereas all such chemical shift differences are small for the protons of the benzo[a]pyrene moiety. Thus, at intermediate rates of exchange, the nucleoside resonances are broadened beyond recognition, whereas the aminobenzo[a]pyrene resonances appear normal. This is linked with the large anisotropic ring‐current field from the carcinogen ring system, and restricted internal rotation at the site of attachment of the carcinogen to the nucleic acid base. The possibility of an absence of resonances from a nucleoside moiety can complicate structure elucidation of unknown carcinogen‐nucleoside adducts and related compounds, especially in trace analysis.
Molecular modeling and NMR spectroscopic examination of (E)‐cyclodec‐5‐enone and its 2 ‐and 10‐methyl analogs
Authors: Chu Yongliang , Colclough David , White James B. , Smith William B.
Published: May 2005

The 1H and 13C NMR spectra of (E)‐cyclodec‐5‐enone and its 2‐ and 10‐methyl analogs were determined. The 1H NMR spectrum of the former was determined over the temperature range −60 to 20°C. Information from the 2‐D INADEQUATE spectrum of the parent compound was combined with that derived from the homonuclear and heteronuclear correlation spectra to assign the olefinic proton at C‐6. In all three proton spectra, this was the only set of resonances sufficiently well defined to allow conformational information to be deduced. Molecular modeling by molecular mechanics, semi‐empirical and ab initio molecular orbital methods were used to predict conformational preferences. These results were then compared with the NMR data.
Structural assignment of (σ‐π)palladium complexes
Authors: Gogoll Adolf , Grennberg Helena
Published: May 2005

A series of (σ‐π)palladium complexes derived from cyclooctadiene were investigated by 1H, 13C and 19F NMR. The stereochemical assignment was based on intramolecular NOEs in conjunction with molecular modelling and semi‐empirical methods, and confirmed by interligand NOEs in nitrogen chelate complexes derived from the title compounds. The nitrogen chelating ligands are involved in a rotation with respect to the ligand‐palladium axis.
19F NMR study of 1‐halo‐F‐adamantanes
Authors: Adcock James L. , Luo Huimin , Dai Sheng
Published: May 2005

An ‘anomalous’ variation of β‐fluorine chemical shifts with respect to the inductive effect in the 19F NMR of a series of 1‐halo‐F‐adamantanes is reported. These fluorine chemical shifts are similar to the hydrogen chemical shift anomaly found in the corresponding hydrocarbon halides. Whereas the γ‐hydrogen chemical shifts can be rationalized by the inductive effect, the γ‐fluorine chemical shifts have the same ‘anomalous’ variation as found in the β‐fluorine chemical shifts.
15N NMR study of dialkyl, N‐alkyl‐N′‐phenyl and diphenyl sulphur diimides: Assignment of configuration in solution
Authors: Wrackmeyer Bernd , Köhler Christian , Herberhold Max
Published: May 2005

15N NMR spectra of dialkyl sulphur diimides (1) [R1(NSN)R2; R1 = R2 = Me (a), Et (b), nPr (c), iPr (d), nBu (e), tBu (f), tOct (g)], N‐alkyl‐N′‐phenyl sulphur diimides (2) [R1(NSN)R2; R1 = Me (a), Et (b); R2 = Ph] and diphenyl sulphur diimide (3) were measured at variable temperature. The assignment is based on the comparison with data for the corresponding N‐sulphinylamines R1(NSO). The Z/E configuration is always preferred at low temperature, whereas the minor isomer adopts the Z/Z configuration. In the presence of bulky substituents (If and g), only the isomer with Z/E configuration is observed. At room temperature, 15N NMR signals were not observed for symmetrically substituted sulphur diimides, but a single averaged 14N resonance can be measured. The unsymmetrically substituted sulphur diimides 2a and b adopt the Z/E configuration with the alkyl group Z and the phenyl group E. There are no indications of other isomers at low temperature. 14N NMR spectra at room temperature prove that the (Z)‐phenyl/(E)‐alkyl isomer contributes little to the equilibrium.
Applications of Raman magnetic resonance to heteronuclear spin systems
Authors: Yang Daiwen , Ye Chaohui
Published: May 2005

Raman magnetic resonance (RMR) with direct and indirect detection schemes features 1D display of multiple quantum (MQ) transitions. Consequently, useful information such as couplings and correlations can be easily extracted from the RMR approach. In this paper, RMR experiments are demonstrated to determine heteronuclear chemical shift correlations, homonuclear and heteronuclear long‐range coupling constant values and their relative signs, with typical samples. It is shown that this approach is useful for the study of small molecules and groups of special interest in a complex molecule.
Solvation and metal ion effects on structure and reactivity of phosphoryl compounds. Part 3—conformational analysis of 2‐substituted alkylphosphonates by phosphorus‐31‐carbon‐13 coupling constants
Authors: Belciug Marie‐ P. , Wessels Philippus L. , Modro Tomasz A.
Published: May 2005

One‐ and three‐bond P,C coupling constants in the phosphonate skeleton of dimethyl esters of 2‐hydroxy (or 2‐methoxy) alkylphosphonic acids were determined from 13C NMR spectra recorded in various solvents and in the presence of metal ions. The results confirmed earlier conclusions about the intramolecular attractive interactions between the OH (OMe) and the phosphoryl groups, enhanced by the complexation with Na+ or Mg2+ ions. Reasonable correlation between the 3J(P,C) values and the population of the conformer involving the trans orientation of the phosphonate group and the C‐3 carbon atom was obtained.
Detection of NOE interaction between components of organic π‐complexes
Authors: Hoffman Roy E. , Rabinovitz Mordecai
Published: May 2005

Homonuclear 1H, 1H NOE effects were observed for π charge‐transfer complexes of 2,4,6‐trinitrotoluene (TNT) with aromatic hydrocarbons using a 1D‐NOESY experiment. The intensity of the NOEs indicates that the structure in solution is analogous to that in the solid state as determined by x‐ray crystallography.
Solution and solid phase 13C NMR studies of cyclic and acyclic 1,2‐dialkoxybenzenes and their mononitro derivatives
Authors: Buchanan G. W. , Driega A. B. , Ratcliffe C. I.
Published: May 2005

13C NMR chemical shifts are reported for 1,2‐dimethoxybenzene (veratrole) and related benzodioxane, benzodioxepane and benzodioxenane systems and their 4‐nitro derivatives in solution and in the solid state. Results are discussed in terms of the stereoelectronic influence of substituents.
1H 2D‐NMR characterization of Ni(II)‐substituted azurin from Pseudomonas aeruginosa
Authors: Moratal José‐María , Salgado Jesús , Donaire Antonio , Jiménez Hermas R. , Castells Josep , Martínez‐ferrer María‐josé
Published: May 2005

1H two‐dimensional NMR experiments on nickel(II)‐substituted azurin have been successfully applied. Despite the short relaxation times of the hyperfine‐shifted resonances, the combined use of NOESY and COSY spectra allowed the assignment of 15 resonances belonging to the metal‐coordinated residues Gly‐45, His‐46, His‐117 and Met‐121. Even in the case of the two broad and furthest downfield resonances, the NOESY spectra were successful in assigning these signals to the β‐CH2 protons of Cys‐112. The protons of the non‐coordinated residues Met‐13, Phe‐15 and Trp‐48 were also assigned via NOESY, COSY and TOCSY experiments.
Determination of the methionine haem ligand conformation in cytochrome cH from Methylophilus methylotrophus by two‐dimensional 1H NMR
Authors: Santos Helena , Turner David L.
Published: May 2005

A complete relaxation matrix approach was used to determine the conformation of the Met ligand to the haem in Methylophilus methylotrophus cytochrome cH, including the configuration at the sulphur; the pattern of NOEs is shown to be dominated by spin diffusion at mixing times as short as 25 ms, rendering the two‐spin approximation unreliable. The Met conformation, together with an analysis of aromatic proton resonances, indicates a structure almost identical with that found by x‐ray crystallography for Pseudomonas aeruginosa cytochrome c551, which has a 45% similarity in sequence. The paramagnetic shifts of the haem methyl proton resonances in the oxidized protein support the view that the asymmetry in the electronic structure of the haem is dominated by the orientation of the Met ligand.
Assignment of the 1H and 13C NMR spectra of 132(R)‐methoxychlorophyll a using the two‐dimensional HMQC and HMBC techniques
Authors: Kilpeläinen Ilkka , Kaltia Seppo , Kuronen Pirjo , Hyvärinen Kristiina , Hynninen Paavo H.
Published: May 2005

The 1H and 13C NMR spectra of 132(R)‐methoxychlorophyll a were assigned utilizing the two‐dimensional 1H‐detected heteronuclear one‐bond (HMQC) and multiple‐bond (HMBC) correlation techniques. The protons and carbons of the macrocycle and its short side‐chains could be completely assigned using the HMQC and HMBC data in concert. These techniques were also valuable in achieving assignments for the phytyl chain, which were previously incomplete. The proton and carbon assignments of the P1‐CH2, P2‐CH, P4‐CH2 and P15‐CH groups and those of all methyl groups of the phytyl chain could be established by the coupling patterns and by the combined information obtained from the HMQC and HMBC connectivities. Fairly unambiguous proton and carbon assignments were also obtained for the P6‐CH2, P7‐CH, P9‐CH2, P11‐CH and P14‐CH2 groups. The sensitivity of the HMQC and HMBC techniques is good, making it possible to achieve the spectral assignments under high dilution and monomeric conditions. This was considered to be of paramount importance in the structural analysis of chlorophylls and related compounds, which are difficult to prepare in adequate amounts and purity because of their lability and which show a strong aggregation tendency at higher concentrations and lower temperatures.
Application of modified selective polarization transfer experiments to the structural analysis of β‐silylated silyl enol ethers by 1H, 13C and 29Si NMR
Authors: Baudrillard Vincent , Davoust Daniel , Ple Gerard
Published: May 2005

The 1H, 13C and 29Si NMR spectral characteristics of β‐silylated silyl enol ethers were determined. nJ(Si, H) measurements (2 < n < 4) were achieved from selective polarization transfer experiments with selective decoupling during acquisition. 1H,29Si two‐dimensional heteronuclear correlation confirmed the positions of the silylated groups in the molecules.
1H1H and 1H19F coupling constants of some styrene, benzaldehyde and benzylidene amine derivatives
Authors: Suntioinen Sirpa , Laatikainen Reino , Král Vladimir
Published: May 2005

Five para‐fluorobenzene derivatives having a CHCR2 or a CHNR group were prepared and their 1H and 19F NMR spectra in acetone‐d6 were analysed. The 6J(Hα,F) and 4J(Hα,H) couplings of the nitrogen derivatives fall between those of the carbon and oxygen derivatives: the electronegativity of the side‐chain β‐atom seems to have a prominent role in the spin information transmission. The 6J(Hα,F) and 4(Hα,H) couplings indicate that the nitrogen derivatives are rigidly planar whereas the carbon derivatives are non‐planar.
Demonstration of the linear dependence of proton magnetization transfer on polymer concentration in aqueous gels at two different field strengths
Authors: Tessier Jean J. , Potter Kimberlee , Carpenter T. Adrian , Hall Laurance D. , Tyler Jenny A.
Published: May 2005

Saturation transfer experiments were performed at both 85 and 300 MHz to measure the magnetization transfer (MT) rate as a function of macromolecular concentration. For this purpose calcium alginate gels with an internal concentration gradient were manufactured from aqueous sodium alginate and calcium ions. Although aqueous sodium alginate did not exhibit any MT, the proton magnetization transfer rate in calcium alginate gels was found to depend linearly on the concentration of polysaccharide. Since the rate did not depend on the field strength, the dominant mechanism of MT in these systems is either chemical exchange or a highly efficient intermolecular cross‐relaxation process. The high sensitivity of MT to variation in polysaccharide concentration and mobility suggests that it is an excellent tool to monitor changes in the chemistry, mobility and concentration of slowly moving polymers in aqueous gels.
1H and 13C NMR assignment of sodium chenodeoxycholate in aqueous solution. Polarization of bile salts steroid nucleus
Authors: Zakrzewska J. , Okon M. , Vučelić D.
Published: May 2005

1H and 13C NMR assignments of sodium chenodeoxycholate in aqueous solution were obtained for three different bile salt concentrations. 1H and 13C NMR chemical shifts of sodium chenodeoxycholate and deoxycholate show slight concentration dependence due to micelle formation. Opposite trends in chemical shifts changes for α‐ and β‐protons cause polarization of the steroid nucleus.
1H and 13C NMR analysis of C‐23 and C‐24 diastereomers of 5α‐dinosterane
Authors: Stoilov Ivan , Smith Stanford L. , Watt David S. , Carlson Robert M. K. , Fago Frederick J. , Moldowan J. Michael
Published: May 2005

Detailed analysis of the 1H and 13C NMR spectra of four diastereomers of the important geochemical biomarker (20R)‐5α‐dinosterane was completed using various two‐dimensional 1H1H and 1H13C correlation techniques.
15N NMR: Substituent effect analysis in para‐and meta‐substituted phenylhydrazines
Authors: Mezzina Elisabetta , Ferroni Fiammetta , Spinelli Domenico , Chimichi Stefano , Frenna Vincenzo
Published: May 2005

15N NMR spectra of phenylhydrazine and of 14 para‐ and meta‐substituted phenylhydrazines were measured at natural isotope abundance in DMSO‐d6 solution. The substituent present exerts a larger influence on the chemical shift of the nitrogen atom directly bound to the aromatic ring (N‐1) than on the second one (N‐2), which shows an attenuated and inverted trend. The chemical shifts of N‐1 and N‐2 give a good cross correlation in both series of compounds if p‐NO2 and m‐F derivatives are excluded from the correlations of para‐ and meta‐substituted phenylhydrazines, respectively. Moreover, N‐1 SCS values show good linear correlations with Hammett substituent constants, with SCSs of directly bound hydrogen (H‐1) and with aniline nitrogen SCSs. The results of dual substituent parameter analysis are also reported together with a comparison of 13C and 15N chemical shifts with those of monosubstituted benzenes and substituted anilines.
Structural studies on chiral (π‐Allyl)Pd(II) complexes. 1H, 13C and 31P NMR Studies of [Pd(η3‐CH3CHCHCH2)(S, S‐Chiraphos)] CF3SO3
Authors: Pregosin Paul S. , Salzmann Renzo
Published: May 2005

The chiral (π‐allyl)Pd(II) complex [Pd(η3CH3CHCHCH2)(S, S‐Chiraphos)]CF3SO3 was shown to exist in four isomeric forms (two diastereomeric and two geometric). Aspects of their three‐dimensional structures were elucidated using 1H, 13C and 31P one‐ and two‐dimensional NMR methods. The assignment of the diastereomers, which differ with respect to the coordinated face of the allyl ligand, was achieved using 1H‐NOESY methods.
Enhanced diagnostic EPR and ENDOR spectroscopy of radical spin, adducts of deuterated α‐phenyl N‐tert‐butyl nitrone
Authors: Haire D. Lawrence , Janzen Edward G.
Published: May 2005

Deuterated analogues of C‐phenyl N‐tert‐butyl nitrone (PBN) were synthesized to provide significant gains in spectral sensitivity and resolution in electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) applications. Three deuterated α‐phenyl N‐tert‐butyl nitrones (PBNs) were prepared. EPR spectra of the corresponding radical spin adducts with the phenyl ring (PBN‐d5‐R˙) or tert‐butyl moiety (PBN‐d9‐R˙) deuterated were found to enhance disclosure of the structure of the added radical. The most dramatic increases in EPR resolution, however, were not realized until both the phenyl and tert‐butyl groups were deuterated (PBN‐d14‐R˙). Here, baseline resolution of unique long‐range (e.g. γ‐ and δ‐) hyperfine splittings from the radical addend could be displayed. Representative radical spin adducts of PBN‐d14 (methyl, hydroxyl, aminyl, cyanyl, carbamoyl, and vinyl) were prepared and compared with those of PBN to illustrate this point. It is also shown that when even higher spin adduct resolution is desired the combination of spin trap deuteration and ENDOR may be applied to advantage.
1H and 13C NMR spectral assignments of some phenothiazine derivatives
Authors: Pelecanou M. , Mikros E. , Catsoulacos P.
Published: May 2005

1H and 13C NMR data for six pheno‐thiazine derivatives are reported. Spectral assignments were made on the basis of two‐dimensional homonuclear 1H,1H and heteronuclear 1H,13C correlation techniques (COSY, COSY‐LR, HETCOR, COLOC) and 13C,1H coupling constant measurements.
Structural assignment of the 1H and 13C NMR spectra of 3‐Cyano‐1,2,2‐trimethyl‐6‐azatricyclo [3.3.1.03,8] non‐6‐ene using two‐dimensional NMR spectroscopy
Authors: Caronna Tullio , Luogo Daniela Dal Pio
Published: May 2005

1H NMR of the tricyclic molecule 3 ‐ Cyano ‐1,2,2‐ trimethyl ‐ 6 ‐ azatricyclo ‐[3.3.1.03,8]non‐6‐ene does not permit the distinction between this structure and the other regioisomer that can be formed in a photochemically induced reaction. The elucidation of the structure was possible via the assignment of the 1H and 13C NMR spectra of this compound obtained using two‐dimensional NMR spectroscopy.
Assessment of NMR probe temperature stability and gradient using a nematic phase solution
Authors: Farrant R. D. , Lindon J. C.
Published: May 2005

The measurement of the 1H NMR spectrum of a sealed sample of benzene dissolved in a nematic liquid crystal provides a convenient and sensitive test of both NMR probe temperature stability and of the temperature gradient across the sample.
55Mn, 13C coupling constants of some σ‐ and π‐organomanganese complexes
Authors: Torocheshnikov Vladimir , Rentsch Daniel , von Philipsborn Wolfgang
Published: May 2005

55Mn, 13C coupling constants of σ‐ and π‐organomanganese pentacarbonyl, tetracarbonylphosphine and tricarbonyl complexes were determined by lineshape analysis of the 13CO and 13C(R) signals (R = alkyl, acyl or aryl) using the iterative lineshape fitting program QUADR. The 1J(55Mn, 13C) data are in the range 29–47 Hz for MnCO bonds and 2–28 Hz for MnR bonds. The 55Mn chemical shifts and linewidths are also reported.
14N NMR spectroscopy of NH4+ as a probe of ion‐exchange membranes
Authors: Haryadi  , Rankothge M. , Hook J. , van Gorkom L. , Moran G.
Published: May 2005

14N NMR Spectroscopy of NH4+ is a convenient and sensitive probe of structure and mobility in Nafion, Dow and Neosepta cation‐exchange membranes. NH4+ ions bound to these commercially produced membranes give rise to small 14N quadrupolar splittings ranging from 10 to 160 Hz. Moderate stretching of Nafion and Dow membranes induces much larger splittings of up to 2 kHz. The splitting has also been found to be dependent on the orientation of the membranes in the magnetic field B0. In Nafion it reaches a minimum at an angle of 45–55° between the direction of stretch and B0. The quadrupolar splittings also increase with increase in temperature. 14N spin–lattice relaxation times in all three membranes at 300 K are about 20 times shorter than in aqueous solution, consistent with strongly bound NH4+ ions. The apparent activation energies for 14N relaxation, derived from the temperature dependence of the T1, data, show that reorientation of the bound NH4+ ions requires ca. 20 kJ mol−1 in Nafion and Dow membranes and ca. 30 kJ mol−1 in Neosepta, compared with 6.5 kJ mol−1 for free NH4+ in aqueous solution.
Study of the π‐electron distribution in push—pull alkenes by 1H and 13C NMR spectroscopy. Part III—the conformation of 3,4‐dihydro‐4‐oxo‐2H‐thiins
Authors: Kleinpeter E. , Heydenreich M. , Chatterjee S. K. , Rudorf W.‐D.
Published: May 2005

The 1H and 13C NMR spectra of a variety of differently 2,5,6‐trisubstituted 3,4‐dihydro‐4‐oxo‐2H‐thiins (integrated push–pull alkenes) were unequivocally assigned by means of a wide variety of 1D and 2D NMR spectroscopic methods. The NMR parameters thus obtained, together with the results of accompanying force‐field calculations, proved useful in determining the preferred ring conformation of 3,4‐dihydro‐4‐oxo‐2H‐thiin (half‐chair). Additionally, the 13C chemical shift difference, Δδ(C‐5, C‐6), could be employed to indicate the degree of bond polarization of the partial C‐5C‐6 double bond (push–pull character); the barrier to rotation, otherwise used to estimate this parameter characterizing the push–pull alkenes, cannot be applied owing to the ring fusion. Interestingly, NH2 proved less effective in C‐5C‐6 bond polarization than NHPh.
Substituent effects of 1H NMR parameters of chlorinated diphenyl ethers. A statistical approach
Authors: Nevalainen Tapio , Kolehmainen Erkki
Published: May 2005

The 1H NMR spectra of 64 polychlorinated diphenyl ethers (PCDEs) were measured and assigned. Multiple linear regression analysis was used to estimate the effects of chlorine atoms on the 1H NMR chemical shifts and coupling constants. The ‘simple sum rules’ were found to be inadequate for the prediction of 1H NMR chemical shifts of PCDEs. Therefore, corrective terms of two chlorine atoms were taken into account. The most important effects on chemical shifts were shown to be the steric interactions of two adjacent chlorine atoms and the intramolecular ring current effect observed in the ortho‐proton of tri‐ortho‐substituted PCDEs. The substituent effects on J(HH) coupling constants were found to be approximately additive. An interannular coupling between ortho‐protons [6J(HH) = 0.05–0.15 Hz] of adjacent rings was observed.
Nitrogen NMR of some sulphur diimide anions and calculated (GIAO) nitrogen shielding constants
Authors: Wrackmeyer Bernd , Gerstmann Silke , Herberhold Max , Webb Graham A. , Kurosu Hiromichi
Published: May 2005

Sulphur diimide anions of the type [NSN]2− (1), [RNSN]− (1), [R = tBu (3), SiMe3 (4), tBu2P (5)] were prepared with the counter ions [nBu4N]+ or [(Me2N)3S]+ (for 1, 3, 4) and K+ (for 5) and studied in solution by 14N NMR, and for assignment purposes by 15N NMR (4). The experimentally determined 14N chemical shifts (δN) were compared with nitrogen shielding constants calculated by the gauge included atomic orbitals (GIAO) technique, and a linear relationship between σN(calc) and δN was obtained. This correlation serves to support the Z configuration of the anions [RNSN]−, analogous to the isoelectronic N‐sulphinylamines. On this basis, two 14N resonance signals reported in the literature with uncertain assignment can be attributed to [HNSN]− (2), and the previously assigned δN values suggest that the anion [HNSNS]− (6) adopts the Z/E configuration.
1H and 13C NMR study of new organic nitrate esters. I. (2H)‐1,3‐benzoxazin‐4‐(3H)‐one derivatives
Authors: Bertolini Giorgio , Conti Sonia , Ferrario Francesco , Sala Alberto
Published: May 2005

The 1H and 13C NMR of a series of 3‐nitrooxyalkyl‐2H‐1,3‐benzoxazin‐4‐(3H)‐ones were measured and assigned on the basis of substituent chemical shifts, DEPT experiments and 13C/1H shift correlated spectra.
Characterization of the unsymmetrical trimer of indole‐5‐carboxylic acid by proton NMR spectroscopy
Authors: Mackintosh J. G. , Mount A. R. , Reed D.
Published: May 2005

Indole‐5‐carboxylic acid trimer, a major product formed during the electro‐polymerization of indole‐5 carboxylic acid, was characterized by 1H NMR spectros‐copy, and a wide range of one‐ and two‐dimensional NMR techniques were employed to allow full analysis of the 1H spectrum. Homonuclear NOE experiments were carried out in different solvents and at different temperatures, owing to the unusual observation of negative enhancements in some experiments. This was shown to be due to the slow tumbling rate of the molecule.
Investigation of the electronic structure of 4‐chlorophenylisoxazole and 4‐chloroisoxazoline by NQR spectroscopy and quantum‐chemical calculations
Authors: Poleshchuk O. Kh. , Nogaj B. , Latosińska J. N. , Koput J. , Babushkina T. A. , Sokolov S. D.
Published: May 2005

35Cl NQR spectra of substituted phenylisoxazoles and isoxazolines were analysed. For certain molecules the atom charges and orbital populations were calculated with the MINDO/3 method. It was proved that a chlorine atom at position 4 on an isoxazole ring transmits the influence from the phenyl ring at position 3 to the phenyl ring at position 5 on the isoxazole ring through the system of π‐bonds.
Synthesis of pentasubstituted pyridines. II—NMR study of the addition products of 1‐(N,N‐diethylamine)prop‐1‐yne to methyl 2‐isothiocyanato‐3‐phenylpropenoate
Authors: Peláez‐Arango Elvira , López‐Ortiz Fernando , Barluenga José , Ferrero Miguel , Palacios Francisco
Published: May 2005

The structure of the pentasubstituted pyridines obtained in the reaction of methyl 2‐isothiocyanato‐3‐phenylpropenoate with 1‐(N,N‐diethylamine)prop‐1‐yne were assigned based on 2D heteronuclear correlation experiments and NOE measurements. At 0°C a 2‐azabicyclo[2.2.2] octa‐2,7‐diene intermediate was isolated and spectroscopically characterized.
Comparative multinuclear (35Cl,79Br,81Br,127I and17O) magnetic resonance study of the perhalate anions XO4−(X  Cl, Br or I) in acetonitrile solution
Authors: Dove Michael F. A. , Sanders Jeremy C. P. , Appelman Evan H.
Published: May 2005

The NMR spectra (35Cl,79Br,81Br,127I and17O) of the tetrahedral perhalate anions XO4−(X  Cl, Br and I) were compared for the first time in acetonitrile solution, a medium in which the resonances are relatively sharp and in which no oxygen exchange occurs. Relaxation studies of the quadrupolar nuclei in these solutions at 24°C are reported and show that excellent spectra may be obtained at 0.1 M concentration; thus the observation of separate resonances for Cl16O4−and Cl18O16O3−represents the first reported instance of a35Cl secondary isotopic shift [1Δ35Cl(18.16O) = ‐0.090 ppm]. Enrichment with17O of all three ions was carried out and the1J(127I,17O) coupling constant (489 Hz) has been observed for the first time. The chemical shifts and coupling constants are discussed, especially in connection with the anomalous properties of the perbromate ion. Halogen chemical shifts for BrO3F, IF7and IF6+AsF6−are reported for the first time.
NMR study of iminophosphine oligomers by 31P, 15N and 31P, 13C heteronuclear shift correlation
Authors: Gudat D. , Link M. , Schröder G.
Published: May 2005

2D 31P, 15N heteronuclear shift correlation, based on a non‐refocused INEPT pulse sequence with 15N detection, was applied to a 15N NMR study of the azadiphosphiridines 1‐5 which are formed by [2 + 1] cycloaddition of iminophosphines, RPNR′. The pulse sequence used allowed consistent assignment of both the 31P and 15N NMR spectra in one experiment; by a slight modification, also the signs of numerous 31P‐15N coupling constants across one or two bonds could be determined. Comparison of the data with those of the azatriphosphetidine 6 (obtained from ID 1H,15N and 31P,15N INEPT spectra) showed the influence of the ring size and conformational effects on the NMR parameters. 31P,13C shift‐correlated 2D spectra were further used to measure (including sign determination) and assign 31P‐13C coupling constants across one to three bonds in 1‐5. Based on the analysis of the coupling information and the known conformation of 4a, the relative stereochemistry of the diastereomers 4a and b could be derived; further, the comparison of the 31P‐13C coupling data of 1‐3 with those of the 4a and b allowed the conformations of these derivatives, which were previously unknown, to be determined. The derived information of the constitution and stereochemistry of 1‐5 gives insight into mechanistic details of the iminophosphine [2 + 1] cycloaddition.
NMR visibility of 35Cl− in human erythrocytes
Authors: Riddell Frank G. , Zhou Zhe
Published: May 2005

Contrary to previous reports, Cl− is visible by 35Cl NMR inside human erythrocytes. In spectra run at 49.01 MHz the intracellular chloride has a linewidth at half‐height of ca 700 Hz and shows double Lorentzian character. Mn2+ was used to relax the extracellular 35Cl− to allow the intracellular 35Cl− to be seen. The experimental protocol described should allow NMR observation of anion transport rates in human erythrocytes.
Complete assignment and additivity rule for 1H and 13C chemical shifts of non‐planar, nonacyclic aromatic hydrocarbons
Authors: Ueda Toyotoshi , Iwashima Satoshi , Aoki Junji , Takekawa Minoru
Published: May 2005

Complete assignments of 1H and 13C NMR spectra were made for heptacyclic peropyrene and five isomers of dibenzoperopyrenes, using 2D correlation spectroscopic techniques of homonuclear HH‐COSY and NOESY and heteronuclear CH‐COSY and HMBC methods. New additivity rules of 1H and 13C chemical shift values were established for compounds having two types of benzene ring condensation. All 1H chemical shifts were satisfactorily interpreted by a very simple magnetic point dipole model. This model includes net contributions from each constituent benzene ring due to the ring current anisotropy and permits some ring planes to deviate from the mean molecular plane. The conjugated ring currents are consistent with the chemical shifts. Thus, the aromatic properties are normal even if the molecular skeleton is considerably deformed and becomes non‐planar.
Solid‐state 13C NMR investigations of monosubstituted cyclohexanes in thiourea inclusion compounds
Authors: Müller Klaus
Published: May 2005

Thiourea inclusion compounds with substituted cyclohexanes bearing polar or non‐polar substituents were studied by dynamic 13C magic angle spinning NMR spectroscopy. Variable‐temperature experiments were performed to evaluate the specific features of the guest molecules comprising both the kinetic and the thermodynamic aspects. Further information was also obtained about potential guest‐host interactions which might have a bearing on the molecular behaviour of the guest species. Quantitative analysis in these experiments revealed that within the temperature range covered, the relaxation behaviour is dominated by ring interconversions of the guest molecules. In addition, reorientational motions of the guest molecules exist on a very fast time‐scale which are responsible for the observed significant reduction in the anisotropic magnetic interactions. The most prominent results are the evaluated unusual conformational equilibria. It is shown that the thiourea host lattice obviously stabilizes the axial conformational state. This is true for all systems with polar substituents whereas for those with non‐polar substituents the conformational equilibria are not affected. These findings are related to specific guest‐host interactions, probably of a polar nature.
NMR studies of exchanging amide protons in 1‐desamino‐8‐D‐argininevasopressin by selective Hartmann‐Hahn transfer
Authors: Zangger Klaus , Sterk Heinz
Published: May 2005

Proton exchange rates between the solvent H2O and the amidic protons of a nonapeptide (1‐desamino‐8‐D)‐argininevasopressin in aqueous solution were determined by using selective nuclear magnetic double‐resonance methods. Transverse magnetization, the magnitude of which depends on the chemical exchange rate and the relaxation time T1, is transferred via doubly selective homonuclear Hartmann‐Hahn mixing to a scalar coupling partner. With respect to well established two‐dimensional experiments, this one‐dimensional alternative has two advantages: it is much less time consuming and, as a true benefit, it is even applicable when two signals which are in exchange with the same compound (solvent) are overlapping. The evaluation of amide proton exchange rates in the investigated peptide led to the assumption of an intramolecular hydrogen bond.
Conformational and configurational study of 1,3‐dioxolanes by proton and carbon NMR spectroscopy
Authors: Mucci A. , Schenetti L. , Brasili L. , Malmusi L.
Published: May 2005

The configurational and conformational properties of six 4‐trimethylammoniummethyl 2,2‐disubstituted 1,3‐dioxolanes were studied using NOE experiments and vicinal coupling constants. Selective 1D NOE experiments proved to be effective tools in the configurational assignment of C‐2 relative to C‐4. The preferred conformation of the dioxolane ring and the exocyclic group at C‐4 was obtained by employing vicinal coupling constants and NOE results. The 1H and 13C NMR chemical shifts show stereochemically dependent trends. Quantitative analysis of conformer populations was performed using Haasnoot et al's equation. The N+(CH3)3 group was found to be synclinal with respect to the heterocyclic O‐3 atom and points outside the ring. When a phenyl group is present at C‐2, the 4‐CH2N+— group in a trans relationship to the 2‐phenyl ring was found to occur prevalently in a pseudo‐axial orientation, whereas it was established to be prevalently pseudo‐equatorial when cis with respect to the phenyl ring.
Long‐range proton‐carbon coupling constants. Part II—norbornene systems
Authors: Parella Teodor , Sánchez‐Ferrando Francisco , Virgili Albert
Published: May 2005

Long‐range proton‐carbon coupling constants, nJCH, were measured for some simple norbornene derivatives. Among the influence of substitution pattern, a study of the experimental influence of the double bond in the norbornene skeleton on 2JCH and 3JCH was made, taking into account the previously published experimental data for analogous saturated systems. These experimental data show that structural groups which are several bonds away from the coupling sites, but close in space, can provide important alternative mechanisms for transmission of the heteronuclear coupling.
Karplus‐type dihedral angle dependence for the coupling constants 3J(119SnCC119Sn) and 3J(119SnCC29Si)
Authors: Mitchell Terence N. , Kowall Bernd
Published: May 2005

In compounds of the type Me3SnCH2CHRSnMe3 and Me3SiCH2CHRSnMe3, there is a linear relationship between 3J(H,H) and 3J(119Sn,119Sn) or 3J(119Sn,29Si), respectively, thus providing unequivocal evidence for a Karplus‐type behaviour for the coupling constants 3J(119Sn,119Sn) and 3J(119Sn,29Si). Preliminary Karplus equations are presented on the basis of the available data.
Interpretation of substituent‐induced chemical shifts in 13C NMR spectra of 2‐substituted norbornadienes. Influence of homoconjugation
Authors: Krawczyk Hanna , Szatylowicz Halina , Gryff‐Keller Adam
Published: May 2005

Complete signal assignments and an interpretation of the 13C NMR spectra of bicyclo[2.2.1]hepta‐2,5‐diene and of 12 of its 2‐substituted derivatives are presented. The substituent effects observed at C‐1, C‐2 and C‐3 are very similar to those reported for 2‐substituted propenes and monosubstituted benzenes. Transmission of those effects on C‐5 and C‐6 may be at least partially attributed to the homoconjugative interaction between the double bonds in the systems investigated. The relative importance of the field and the resonance effects at particular positions have been evaluated by the dual substituent parameter analysis of the chemical shift data. Relationships between substituent‐induced chemical shifts and electron densities, calculated by the PM3 method, have been found.
29Si and 13C NMR spectra of tert‐butyldimethylsilyl derivatives of amino acids
Authors: Kubec Roman , Velíšek Jan , Kvíčalová Magdalena , Čermák Jan , Schraml Jan
Published: May 2005

29Si and 13C NMR chemical shifts are reported for tert‐butyldimethylsilyl (TBDMS) derivatives of ten common amino acids. The 29Si chemical shifts of TBDMS derivatives of various functionalities encountered fall into distinct spectral regions. The 29Si chemical shifts correlate linearly (r = 0.999) with the 29Si shifts reported earlier for the trimethylsilyl (TMS) derivatives of the same amino acids, the 29Si chemical shift values in the TBDMS derivatives being larger than those in the TMS derivatives (in SiN groups this downfiled shift varies between 3.8 and 5.8 ppm and in SiO groups between 1.4 and 1.7 ppm).
Determination of signs of coupling constants [1J(77Se29Si), 2J(77Se13C), 3J(77Se1H)] in 2,5‐dihydro‐1,2,5‐selenasilaborole derivatives
Authors: Wrackmeyer Bernd , Köster Roland , Seidel Günter
Published: May 2005

The signs of coupling constants [1J(77Se29Si) > 0, 2J(77Se13CSiMe) > 0,3J(77Se1HSiMe) > 0] were determined for pentaorgano‐substituted 2,5‐dihydro‐1,2,5‐selenasilaboroles [R3 = Me, la; R3 = C(Me)CH2, 1b], and also for derivatives in which the surroundings of the selenium atom were changed by forming a pyridine‐borane adduct (2), by formation of an SeAlCl3 adduct (3) and by π‐complexation with the transition metal fragments [Fe(CO)3] (4) and [Ru(CO)3] (5). The sign determination was achieved by using various types of 2D heteronuclear shift correlations (HETCOR) with 13C, 29Si or 1H detection (HMQC). Some of these experiments had to be modified by z‐filtering or by a Ψ‐BIRD pulse sequence. The change in the magnitude of 1J(13C13C) (la, 58.9 Hz; 4, 33.8 Hz) as a result of π‐complexation follows the trend known for diene complexes.
Investigation of substituted dihydronaphthalenes using 1H and 13C NMR spectroscopy
Authors: Alam Todd M. , Liu Ming‐Eng , Garcia Daryl K. , Hernandez Valerie M. , Malone Richard R. , Chamblee Brian B. , Deck Lorraine M. , Royer Robert E.
Published: May 2005

1H and 13C NMR studies were carried out on the substituted dihydronaphthalene compounds 1,2‐dihydro‐8‐isopropyl‐6,7‐dimethoxy‐2‐methylnaphthalene, 3‐bromo‐1, 2‐dihydro‐8‐isopropyl‐6, 7‐dimethoxy‐2‐methylnaphthalene, 3, 4‐dihydro‐5‐isopropyl‐6, 7‐dimethoxy‐3‐methyl‐1(2H)‐naphthalenone, 1, 2‐dihydro‐6, 7‐dimethoxy‐2, 8‐dimethylnaphthalene, 3‐bromo‐1, 2‐dihydro‐6, 7‐dimethoxy‐2, 8‐dimethylnaphthalene and 3, 4‐dihydro‐6, 7‐dimethoxy‐3, 5‐dimethyl‐1(2H)‐naphthalenone. Complete assignments of the proton and carbon spectra were made using one‐ and two‐dimensional NMR techniques including APT, COSY, NOESY and 1H‐13C HETCOR spectroscopy.