bluuebunny/crossref_metadata_2025_split huggingface dataset:
The NMR spectra of the porphyrins 16—zinc(II) meso‐tetraphenylporphyrin (Zn TPP) as a diamagnetic shift reagent. A quantitative ring current model
Authors: Abraham Raymond J. , Bedford Geoffrey R. , McNeillie David , Wright Brian 
Published: May 2005

AbstractThe facile preparation of zinc(II) meso‐tetraphenylporphyrin (Zn TPP) and derivatives from substituted benzaldehydes and pyrrole, combined with the calculation of ring current shifts in these molecules, provides a useful series of selective diamagnetic shift reagents. The porphyrin‐ligand equilibrium is examined for some nitrogenous bases and the complexation shifts (δP values) are obtained in precisely the same manner as LIS. The parameterization of the double‐dipole model of the porphyrin ring current is given, with the inclusion of the phenyl ring currents and free rotation about the substrate‐Zn bond. Precise agreement with the porphyrin proton chemical shifts and the complexation shifts of the geometrically rigid substrates of pyridine, 4‐picoline and quinuclidine is obtained. In contrast, the 13C complexation shifts in these molecules are subject to additional effects other than the ring current shift.
1H NMR structural increments for alkyl substituted η3‐allyl transition metal complexes
Authors: Benn Reinhard , Schroth Gerhard 
Published: May 2005

AbstractThe 1H NMR spectra of various alkyl substituted η3‐allyl transition metal complexes (MNi, Ru) have been analysed. The chemical shifts of the η3‐allyl protons can be calculated using additive increments; the values of the syn and anti vicinal proton‐proton coupling constants approach each other on alkyl substitution of the η3‐allyl group.
A Study of the behaviour of an analogous series of 2H‐thiopyrans, 6H‐1,3‐thiazines and their derivatives by carbon‐13 and nitrogen‐15 nuclear magnetic resonance
Authors: Rabiller C. , Martin G. J. , Pradere J. P. , Meslin J. C. , Quiniou H. 
Published: May 2005

AbstractThe influence of substituents in a new series of 2H‐thiopyrans, 2H‐thiopyran‐2‐ones (thiones) and their thiazine analogues is examined by means of carbon (13C) and nitrogen (15N) NMR. A linear relationship is shown to exist between the chemical shifts (δ13C or δ15N) of the thiopyrans and the thiazines. This relationship is a good indication of the structural similarity which exists between the two series.
Linear solvation energy relationships VIII—solvent effects on NMR spectral shifts and coupling constants
Authors: Taft R. W. , Kamlet Mortimer J. 
Published: May 2005

AbstractThe solvatochromic comparison method is used to unravel solvent polarity and hydrogen bonding effects on a variety of NMR spectral shifts and coupling constants. Solvent effects are rationalized in terms of the solvatochromic parameters π*, δ, α and β. Properties analyzed include 19F shifts of 5‐fluoroindole, 1H shifts of fluorodinitromethane, tert‐butanol, phenol, 2‐methylbut‐1‐en‐3‐yne, and thioacetamide, 1H and 13C shifts and J(13C1H) coupling constants of chloroform, 13C shifts of acetone, 15N shifts of pyridine, 15N and 29Si shifts of 1‐methylsilatrane, and some J(119Sn,C,19F) coupling constants of polyalkyltin compounds.
Electronic and steric effects in arylphosphoramidates and phosphorimidates as monitored by carbon‐13 nuclear magnetic resonance
Authors: Buchanan G. W. , Morin F. G. 
Published: May 2005

Abstract13C NMR chemical shifts and 13C31P couplings are reported for ten arylphosphoramidates and five arylphoshorimidates. The para‐carbon chemical shifts in the phosphoramidates are interpreted in terms of substantial nitrogen lone pair delocalization into the aromatic ring, a phenomenon which is subject to steric inhibition of resonance. By contrast, in the phosphorimidates the electron release into the phenyl ring is not attenuated by steric congestion. Conformational changes about the arylN bond in all compounds have been monitored by vicinal 31PNC13C couplings.
The diphenyliodonium‐2‐carboxylates: An NMR structure investigation
Authors: Mazza Dario Del , Reinecke Manfred G. , Smith William B. 
Published: May 2005

AbstractDiphenyliodonium‐2‐carboxylate, phenyl 4‐methylphenyliodonium‐2‐carboxylate and phenyl 5‐methyl‐phenyliodonium‐2‐carboxylate have been examined by 1H and 13C NMR spectroscopy. Each compound showed one proton considerably upfield from the others. From the two substituted compounds this was deduced to be H‐6 on the ring containing the carboxylate group. Shift reagents and relaxation measurements were used to make the 13C chemical shift assignments. These data are most consistent with a cyclic, neutral structure for these iodonium carboxylates. The iodine is in the center of a trigonal bipyramid with the unsubstituted phenyl and carboxylate group apical, which places the C‐6 proton in the shielding region of the adjacent phenyl group.
Proton NMR studies of reduced porphyrin compounds
Authors: Harel Yaacov , Manassen Joost 
Published: May 2005

AbstractDetailed 1H NMR studies of ms tetraphenylchlorins (H2TPC), new amino‐ and hydroxypyrroline substituted ms tetraphenylchlorins and ms tetraphenylisobacteriochlorins (H2TPisoB) are presented and discussed. The results obtained are consistent with the general aspects of the ring current models as applied to the parent porphyrins. According to proton chemical shifts a gradual reduction in the magnitude of the ring current is observed in the order ms tetraphenylporphyrin (H2TPP) > H2TPC> ms tetraphenylbacteriochlorin (H2TPB) > H2TPisoB. The 1H NMR spectra show chemical non‐equivalence of the pyrroline ring protons due to adjacent substituents, and effects of steric constraints on the aminoalkyl substituents due to the close vicinity to the meso phenyl rings. The non‐equivalence of the methylene protons of the pyrroline ring produces geminal coupling between the two methylene protons and vicinal coupling with the adjacent pyrroline proton, more pronounced in H2TPCOH and in . Restricted configuration of the methylene groups in the ethyl groups of H2TPCC(H)(CH3)N(CH2CH3)2 produces observable geminal coupling between the methylene protons. 1H NMR reveals the difference between two types of meso phenyls in the chlorins, and three types of meso phenyls in isobacteriochlorins, as reflected in the chemical shifts of the o‐phenyl protons.
The 1H, 13C and 31P NMR spectra of EZ pairs of some phosphorus substituted alkenes
Authors: Duncan Mark , Gallagher Michael J. 
Published: May 2005

AbstractThe olefins Ph2P(X)CHCHR [X=lone pair, O, S, Ch3I; RCh3, ph, P(X)ph2] have been prepared and their 1H, 13C and 31P NMR spectra measured. trans 3J[P(IV)C] (range 18.3–25.7 Hz) is greater than cis 3J[P(IV)C] (range 6.9–11 Hz) but this relationship does not hold for P(III) compounds. In the 31P spectra the E isomer absorbs to higher field than the Z isomer for P(III) and P(IV) compounds. The 1H data are in accord with previous results; average substituent shielding coefficients for ph2P(X) substituted alkenes are reported.
Carbon‐13 nuclear magnetic resonance spectra of aminocyclohexanecarbonitriles and comparison with phencyclidine analogues
Authors: Bailey Keith , Legault Donald 
Published: May 2005

AbstractThe 13C NMR spectra of 20 aminocycloalkanecarbonitriles were determined in CDCl3. The signals were assigned by a self‐consistent analysis of chemical shift data and comparison with results from phencyclidine analogues. The results were interpreted in terms of changes in the amine (primary, secondary, tertiary) and the cycloakane (cyclohexane vs cyclopentane) moieties and their bulk. Changes in the conformational equilibria of the cyclohexane series are suggested by comparisons between data from the carbonitrile and phencyclidine series. The spectra are suitable for corroborative authentication of reference materials and the identification of unknowns.
1H NMR studies of solvent and substituent effects on strong intramolecular hydrogen bonds
Authors: Brzezinski Bogumił , Szafran Miroslaw 
Published: May 2005

AbstractChemical shifts of H‐bonded protons in tetrabutylammonium hydrogen maleate and 14‐substituted picolinic acid N‐oxides have been measured in a number of dry solvents, of different activity, in order to distinguish between symmetrical single minimum and asymmetrical hydrogen bonds. In tetrabutylammonium hydrogen maleate the resonance was observed at 20.70 ppm and its was independent of the nature of the solvent used. The chemical shift value of picolinic acid N‐oxide varies with the solvent. These observations suggest that the hydrogen bond is symmetrical in tetrabutylammonium hydrogen maleate but that it is asymmetrical in picolinic acid N‐oxide. The chemical shifts of substituted picolinic acid N‐oxides were correlated with σp, σm and ΔpKa. The substituent and solvent effects are compared and the position of the intramolecular H‐bonded protons in picolinic acid N‐oxides are estimated and discussed.
Carbon‐13 NMR signals of some benzodiazepine drugs
Authors: Patra Amarendra , Mukhopadhyay Apurba K. , Mitra Alok K. , Acharyya Aditi K. 
Published: May 2005

AbstractSome carbon‐13 NMR signal assignments of diazepam, flurazepam, clonazepam and chlordiazepoxide have been revised and the assignments of nitrazepam are reported. The assignments of the various resonances were made by considering the changes in chemical shifts produced by the change of substituents and also by comparison with the chemical shifts of model compounds.
A practical paramagnetic relaxation reagent for aqueous solutions
Authors: Bearden William H. , Cargin Valorie M. , Roberson Willie R. 
Published: May 2005

AbstractWhile there is a useable paramagnetic relaxation reagent (PARR) for use in nonpolar or low polarity solvents, there has not been a practical PARR for use in highly polar solvents. A reagent, Gd(NO3)3‐inositol, is described which appears to satisfy this need. The performance of the reagent is given in terms of its effect on the T1, NOE and line width values of N,N‐dimethylformamide. In addition, the application of this reagent to adenosine is also reported.
Derivatives of cis‐NPCl2(NSOCl)2 and (NPCl2)2NSOCl. Part XIV—synthesis and nuclear magnetic resonance study of dimethylamino derivatives of NPCl2(NSOPh)2 and (NPCl2)2NSOPh
Authors: de Ruiter B. , van de Grampel J. C. 
Published: May 2005

AbstractThe compounds trans‐NPCl2−n(NMe2)n(NSOPh)2(n=0‐2iNPCl2−n NMe2)n (NSOPh)2 (n=0‐2) and N2P2Cl4−nl4−n(NMe2)nNSOP2P2Cl4−n(NMe2)nNSOPh(n=0‐4), were prepared from their chloro‐precursors. The substitution follows a completely non‐geminal pathway, and all possible isomers are formed. The observed relative abundance of these isomers shows that the phenyl group exhibits a strong directing effect on the incoming amine. The 1H, 31P and 13C NMR spectra of the most abundant isomers are reported. 2J(CP) couplings within the PNMe2 grouping are affected by the number of substituents at the phosphorus atom. Almost linear relationships exist between the degree of substitution and the chemical shift of C‐1 and C‐4 of the phenyl groups. The effect of substitution on the 13C chemical shifts of these groups is ascribed to inductive effects.
77Se, 13C and 1H NMR investigations on ortho‐carbonyl benzeneselenenyl derivatives
Authors: Llabrès Gabriel , Baiwir Marcel , Piette Jean‐Louis , Christiaens Léon 
Published: May 2005

Abstracto‐Carbonyl benzeneselenenyl compounds with COCH3, CHO and COOCH3 as carbonyl functions and SeCl, SeBr, SeSCN, SeSeCN, SeCN and SeCH3 as selenium‐containing groups, have been studied by 1H, 13C and 77Se NMR spectroscopy. The IR CO stretching frequencies of these compounds are also reported. If the SeCH3 derivatives are excluded, the compounds mainly adopt a planar ‘cis’ conformation, due to an interaction between the CO group and the selenium atom. The range of over 800 ppm for the observed 77Se chemical shifts makes 77Se NMR spectroscopy a powerful tool for physical organic chemists.
Carbon‐13 chemical shift assignments of the nitration products of pyrene
Authors: Kaplan Samuel 
Published: May 2005

Abstract13C and 1H nuclear magnetic resonance (NMR) spectra have been obtained in order to identify the six nitration products of pyrene—1‐nitropyrene, 1,3‐dinitropyrene, 1,6‐dinitropyrene, 1,8‐dinitropyrene, 1,3,6‐trinitropyrene and 1,3,6,8‐tetranitropyrene. 13C chemical shifts in DMSO‐d6 were assigned using empirical rules, with particular emphasis on the additivity of the substituent effects. Carbon spectra of separated dinitromixtures enabled identification of the previously unreported 1,3‐isomer, and proton spectra differentiated the 1,6‐ and 1,8‐ isomers.
Carbon‐13 nuclear magnetic resonance studies of anthraquinones. Part III—correlation of substituent effects for 2‐substituted anthraquinones
Authors: Berger Y. , Berger‐Deguée M. , Castonguay A. 
Published: May 2005

AbstractThe 13C chemical shifts of 2‐substituted and 2,6‐disubstituted anthraquinones have been determined and assigned. The C‐1, 2, 3, 4, 13 and C‐14 chemical shifts of 2‐substituted anthraquinones are correlated with the chemical shifts of monosubstituted benzenes. A three‐parameter correlation with Swain and Lupton's ℱ and ℛ parameters and Schaefer's Q parameter provides relationships for the prediction of all chemical shifts of 2‐substituted anthraquinones from the substituent parameters. Q values for the SCH3, OCOCH3, C2H5 and C(CH3)3 groups are proposed. The two types of correlations are compared for predicting chemical shifts.
Iterative analysis of the 1H NMR spectra of naphthalene (AA′ A″ A‴ BB′ B″ B‴ system) and two of its derivatives
Authors: Cassidei Luigi , Sciacovelli Oronzo 
Published: May 2005

AbstractThe 1H NMR spectra of naphthalene as an eight spin system, and two of its derivatives, 2,4‐dichloro‐ and 2,4‐dinitro‐1‐naphthol, have been completely analysed. The Indor technique has been very useful in the determination of the signs and magnitudes of very small coupling constants. An improved version of the Laocoon 3 program has greatly facilitated the spectral analysis through, first, the knowledge of the dependence of each transition upon the spectral parameters; second, some modifications in the iterative loop which avoid failure of convergence, and, third, the use of a slightly modified diagonalization subroutine which saves 20% CPU computer time. Our data suggest a rather small substituent effect on intra‐ring couplings of the unsubstituted ring. The inter‐ring coupling constants display a negative or positive sign according to an even or odd number of intervening bound, except the all‐trans 6J which is positive. No substituent effect on the inter‐ring couplings has been observed, except a small effect for the all‐trans 6J.
13C NMR studies of isomeric piperidine derivatives with opiate properties and related compounds
Authors: Casy A. F. , Iorio M. A. , Podo F. 
Published: May 2005

AbstractThe 13C NMR spectra of a series of methyl substituted 3‐arylpiperidines and 4‐aryl‐4‐piperidinols and related compounds are reported, and chemical shift data analysed in terms of the configuration and conformation of isomeric pairs. Special attention is given to the γ chemical shift parameter of axial methyl, and the effects of a nitrogen lone pair orbital and hydroxyl or acyloxy group on the chemical shifts of ring and methyl carbons.
CH, CD, CC and HH coupling constants in isotopically enriched cyclobutene
Authors: Hansen Poul Erik , Led Jens J. 
Published: May 2005

Abstract1H, 2H and 13C NMR studies of cyclobutene and a series of isotopically enriched species have led to a determination of the 1H1H, 13C1H, 13C2H and 13C13C coupling constants in these compounds. In agreement with general observations, 1J(CH) is found to depend on the hybridization of the carbon atoms. Likewise, 2J(HH), 2J(CC), 3J(HH) and 3J(CH), but not 2J(CH), depend on the angles between the bonds connecting the coupled nuclei. When comparing cyclobutene with thiete 1,1‐dioxide (thiete sulphone) an increase of almost 20 Hz is observed for 1J(C‐2, H‐2) in the latter compound. All but one of the observed deuterium isotope effects on chemical shifts are negative. In the case of isotope effects upon the one‐bond coupling constants, the obtained values support the results of the theoretical calculations of Sergeev and Solkan.
13C NMR study of ortho‐, meta‐ and para‐ substituted phenyldiphenylamines: Substituent effect correlations
Authors: Grimley Eugene , Collum David H. , Alley Earl G. , the late Layton Bobby 
Published: May 2005

AbstractThe 13C chemical shifts of 11 substituted triphenylamines have been determined and the assignment of these resonances made using intensities, 1H and 19F couplings and predictions from bond additivity relationships. 13C chemical shifts at carbons bearing the substituent and at carbons ortho to the substituent correlated reasonably well with the Q parameter. A multiple regression analysis of chemical shifts with the field and resonance parameters of Swain and Lupton and the Q parameter produced significantly better correlations than those obtained when Q was omitted for these positions. 13C chemical shift correlations for carbons meta and para to the substituent were not significantly better than when Q was omitted. Significant correlations were obtained between field and resonance parameters and 13C chemical shifts of C‐o and C‐p, and C‐i, C‐o, C‐m and C‐p of the non‐substituent bearing phenyl rings in ortho‐ and para‐substituted phenyldiphenylamines, respectively.
Carbon‐13 NMR studies of benzoquinones
Authors: Joseph‐Nathan P. , Abramo‐Bruno D. , Ortega D. A. 
Published: May 2005

AbstractThe assignment of all ring carbons of p‐benzoquinones derived from perezone and from thymoquinone was completed using gated decoupled spectra. The long range proton‐carbon couplings are discussed in terms of the degree of substitution of the quinone ring. The tautomeric interconversion of the two energetically equivalent forms of 2,5‐dihydroxy‐1,4‐benzoquinones has been studied in various solvents and at several temperatures.
Conformational changes in cyclodecanone due to 2H substitution
Authors: Andrews G. C. , Chmurny G. N. , Whipple E. B. 
Published: May 2005

AbstractRecently reported long‐range deuterium isotope shifts of 13C NMR lines in [2‐2H1]cyclodecanones are simply explained on the basis of changes in the averaging of otherwise equivalent conformations.
Effect of the orientation of substituents on the chemical shifts of 13C. IV—13C NMR spectra of N,N‐diisopropylamides and ‐thioamides
Authors: Fritz Hans , Hug Paul , Sauter Hanspeter , Winkler Tammo , Lawesson Sven‐Olov , Pedersen Bjarne Skindhoj , Scheibye Sten 
Published: May 2005

AbstractN,N‐diisopropylamides and ‐thioamides show hindered rotation around the NCH bonds, and the presence of mixtures of conformational isomers can be demonstrated at temperatures below 273 K in solution. 1H and 13C NMR spectra of these conformers are measured and assigned. The 13C data serve to study through‐space effects on 13C chemical shifts, which strongly depend on the conformations of the isopropyl groups. For amides, a through‐space shielding of the N‐methine carbons is found to exist only for conformers in which the methine hydrogen atom is spatially close to the oxygen atom. Chemical shift differences between amides and thioamides can be rationalized in terms of through‐bond and through‐space contributions, and serve for a better understanding of the shift differences in N,N‐dialkylamides and ‐thioamides.
Carbon‐13 NMR spectra of tembamide, aegeline and related amides
Authors: Patra Amarendra , Mitra Alok K. , Ghosh Arundhati , Mukhopadhyay Prabir K. 
Published: May 2005

AbstractCarbon‐13 NMR spectral studies of tembamide (1) and aegeline (2), constituents of Fagara hyemalis and Aegle marmelos respectively, and a series of their structurally related amides (3–13) have been carried out. The assignment of the resonances of two related dimers are also reported. The assignment of the various resonances were made by considering the changes in chemical shifts produced by the change of substituents and also by using 1, 13 and a related compound as model compounds.
Configuration and 13C NMR spectra of alkylcyclopropane derivatives
Authors: Touillaux R. , Van Meerssche M. , Dereppe J. M. , Leroy G. , Weiler J. , Wilante C. 
Published: May 2005

AbstractEight alkylcyclopropane derivatives were prepared in a conventional manner and analysed by 13C NMR spectroscopy. Additivity parameters were calculated from the chemical shifts of the endocyclic carbons, and the configurational structures derived for these compounds are confirmed by the internal coherence found for this set of parameters.
The differentiation of diastereomers by 13C NMR spectroscopy
Authors: Schneider Hans‐Jörg , Lonsdorfer Michael 
Published: May 2005

Abstract13C shifts are reported for diastereomers with halogen, oxygen and amino substituents which are mainly at vicinal chiral centres. The conformer populations underlying the 13C shift analysis can be verified by chemical means, such as change of temperature, solvent polarity (with dihalides), solvent hydrogen bonding capacity (with diols), deprotonation (with diacids) and by molecular mechanics calculations. The latter provide the basis for configurational and conformational assignments with a series of ephedrine derivatives. In accordance with the 13C shift observations, it is found that ephedrine derivatives predominate in conformations with a gauche O and N substituent arrangement, even in cases where hydrogen bonds are absent.
Remote polar substituent effects on 13C NMR spectra of olefinic and aromatic carbons
Authors: Hill E. Alexander , Guenther Howard E. 
Published: May 2005

AbstractChemical shifts of the olefinic carbons of ω‐substituted 1‐pentenes and 1‐butenes and the aromatic carbons of phenylethanes and phenylpropanes have been measured. Correlations with various substitutent constants, electronegativities, NMR data from related chemical systems and calculated electrical fields were evaluated. Although the pattern of results is quite consistent with expectations for a field‐induced shift of π‐electron density, simple correlations of high statistical precision are not found. The general problem of correlating substitutent effects with reactivity and NMR shifts is discussed.
Deuterium nuclear magnetic resonance spectroscopy. 1—Larmor frequency ratio, referencing and chemical shift
Authors: Al‐Rawi Jasim M. A. , Behnam George Q. , Taha Nihad I. 
Published: May 2005

AbstractPrecise values for the ratio of the Larmor frequencies, w1H/w2H, were measured at constant field for various organic compounds. The values of the Larmor frequency ratio depend on carbon‐hydrogen bond hybridization. The best ratio for the ghost referencing of 2H NMR spectra was then determined (6.514399862). This value enables an accurate ghost reference for any 2H NMR spectrum to be derived from the observed 1H NMR frequency of the normal internal reference. Deuterium and proton chemical shifts measured from internal, partially deuteriated TMS under the same conditions are shown to be the same.
Carbon‐13 nuclear magnetic resonance spectra of D‐homoandrostane derivatives
Authors: Marcano Deanna , Rojas Anibal , Méndez Bernardo , De Méndez Jeannette 
Published: May 2005

AbstractThe 13C chemical shift data of a series of ketone, alcohol and ester derivatives of D‐homoandrostane are reported. Homologation effects are discussed, as well as substituent effects on the homologated structures.