bluuebunny/crossref_metadata_2025 huggingface dataset:
Korrosion und Korrosionsschutz metallischer Werkstoffe
Authors: Speckhardt H. , Gugau M. , Hirth F. W. , Biehl K. , Beyer Chr. , Spähn R.
Published: May 2005

In Früheren Veröffentlichungen [1,2] wurde bereits eingehend über die Arbeit auf dem Gebiet der Oberflächentechnik berichtet. Nun gilt es, den derzeitigen Stand darzustellen. Dabei sind fünf Schwerpunkte zu nennen: die Galvanotechnik, die Kavitations‐Korrosion, die Spannungsrißkorrosion, die Untersuchung von Korrosionsvorgängen bei höheren Temperaturen und Drücken, die Schwingungsrißkorrosion.

In jedem dieser Bereiche erfolgt stets eine enge Zusammenarbeit mit der Industrie, sei es z.B. mit Fachfirmen für Galvanotechnik und mit Lohngalvanisierbetrieben, mit Herstellern von Strömungsmaschinen, mit Herstellern und Betreibern von Verbrennungskraftmaschinen, mit der chemischen Industrie und der Mineralölindustrie, mit Stahlwerken sowie auch mit technischen Vereinigungen wie der Gütegemeinschaft Galvanotechnik e.V.

Oftmals erfolgen die Anregungen zur Formulierung und Durchführung von Forschungsvorhaben unmittelbar aus der Klärung von Schadensfällen. Untersuchungen aus diesem Problemkreis sind beispielsweise in [3] beschrieben, aber auch in [4] und [5].

Nachfolgend stellen die wissenschaftlichen Mitarbeiter in der Abteilung Oberflächentechnik Teilgebiete aus ihren derzeitigen Forschungsarbeiten vor. Dabei ist hervorzuheben, daß dies Ausschnitte sind aus langjährigen Untersuchungen, basierend unter anderem auf vorausgegangenen Dissertationen [6–9] und weiteren wissenschaftlichen Publikationen. So wird eine Kontinuität in der Erforschung des Werkstoffverhaltens bei elektrochemischer und kombinierter mechanisch‐elektrochemischer Beanspruchung hergestellt, wobei ständig neue, verfeinerte Untersuchungs‐, Meß‐ und Prüfmethoden Anwendung finden, die zu einem tieferen Verständnis der im einzelnen ablaufenden Schädigungsmechanismen führen und damit die Grundlagen zur Erarbeitung von Maßnahmen zur künftigen Vermeidung oder doch wenigstens Minimierung von Schäden in der Praxis liefern. Dies ist von wesentlicher Bedeutung hinsichtlich der Werkstoffauswahl, der Werkstoffausnutzung, der Betriebssicherheit, der Gebrauchsdauer und der Verfügbarkeit technischer Geräte und Anlagen.
Calculation of Stress Intensity Factors for axial semi‐elliptical surface cracks in a pipe with cladding loaded thermally
Authors: Grebner H.
Published: May 2005

By means of the weight functions method stress intensity factors were calculated for axial semi‐elliptical surface cracks in a pipe with cladding. The component is loaded by a thermoshock. Starting from a stress‐free state the inner surface of the cladding is suddenly cooled down. The time‐dependent temperature and hoop stress distributions of the uncracked component were calculated for the loading case considered. Numerical values of the stress intensity factors at the deepest point and at the surface points of the crack were evaluated at different time steps for a wide range of crack depths and crack lengths.
High Tech Tabakpfeifen
Authors: Wege E.
Published: May 2005

Die heute gemeinhin als High Tech‐Produkte bezeichneten neuen Errungenschaften der Technik sind keinesfalls auf die Industrie beschränkt, sondern werden im privaten Bereich zunehmend genutzt. Auslöser sind oft geschickte, das Bedürfnis nach z. B. Weltraum‐ oder Formel I‐geprüften und bewährten technischen Lösungen weckende Werbekampagnen. Obgleich der reale Nutzen für die einzelne Person gering ist, schafft die private Verwertung oft erst die wirtschaftliche Basis für spezielle Anwendungen im industriellen Bereich. Am Beispiel der Tabakpfeife wird gezeigt, wie eng technischer Fortschritt und Konsum miteinander verzahnt sein können.
Herstellung von Metall‐Matrix‐Verbundwerkstoffen mit metallischen Gläsern
Authors: Blank‐Bewersdorff M. , Köster U. , Schünemann U. , Herold‐Schmidt U.
Published: May 2005

Metallglas‐Bänder zeichnen sich durch sehr hohe Zugfestigkeit und kostengünstige Herstellung aus, so daß die Entwicklung eines Metallglas‐Metallmatrix‐Verbundwerkstoffes ausgesprochen interessant erscheint.

Die vorliegende Arbeit berichtet über erste Ergebnisse, solche Verbundwerkstoffe durch Oberflächenbeschichten, verschiedene Einbettmethoden bzw. ein Festkörperreaktionsverfahren herzustellen.

Dabei wird vorallem der Einfluß der Herstellungsmethoden auf die Grenzflächenhaftung licht‐ und elektronenmikroskopisch untersucht.
Extended use of solvent venting injection techniques for large sample volumes and coupled capillary columns in SFC
Authors: Berg B. E. , Flaaten A. M. , Paus J. , Greibrokk T.
Published: May 2005

The solvent venting injection technique has been tested for 1‐μL injections of lipids in open tubular column SFC. No sample loss during solvent venting was experienced with a 7‐m precolumn at elevated temperatures. The solvent venting technique has also been combined with gas purging to concentrate the sample on‐line with SFC. Injections totalling 10‐50 μL of sample have been performed. The solvent venting techique with minor modifications in the instrumentation was utilized for group separations of triglycerides. Different techniques for solute focusing were tested. The best peak shape was obtained by a combination of phase ratio and low temperature focusing.
Carbon‐13 variable‐temperature study of 1‐hetero‐spiro[2.5]octanes
Authors: Iratçabal P. , Grenier‐Loustalot M. F. , Lichanot A. , Metras F.
Published: May 2005

The conformational preferences of 1‐oxa‐ and 1‐thia‐spiro[2.5]octanes have been determined from lowtemperature 13C NMR spectra. The 13C chemical shifts are discussed in terms of the α, β and γ effects. The energy barrers to inversion of the cyclohexane ring correlate with the energy barriers to internal rotation of the methyl group in 1‐hetero‐2‐methylcyclopropanes.
Analysis of the NMR spectra of trimethylsilyl‐substituted sugars by two‐dimensional heteronuclear 29Si–1H shift correlation spectroscopy
Authors: Liepinsh E. , Sekacis I. , Lukevics E.
Published: May 2005

Two‐dimensional NMR experiments on 29Si‐1H shift correlations in trimethylsilyl‐substituted sugars are described. This technique allows the unambiguous assignment of 29Si and 1H signals of all trimethylsilyl groups.
13C and 31P NMR spectra of 1‐adamantylphosphoryl derivatives
Authors: Duddeck Helmut , Hanna Atef G.
Published: May 2005

The 13C and 31P NMR data of 26 bridgehead phosphorylated adamantanes, adamantyl‐P(O)XY, are reported. The 13C chemical shifts of the α‐carbons are dependent on the X and/or Y group electronegativities, and can be interpreted by assuming pπdπ electron back‐donation from X/Y to P. As expected, 31P chemical shifts cannot be rationalized simply in similar terms. There is an extraordinarily good correlation between α‐carbon chemical shifts and the corresponding 1J(CP) values. A tentative interpretation, based on the proportions of s and p character in phosphorus bond orbitals, is presented. Surprisingly large 4J(PP) values were observed for two bis‐1,3‐dihalophosphophoryladamantanes.
13C chemical shifts and configurational studies of some aryl cyclopropyl sulphones
Authors: Bhaskar Reddy D. , Balaji T.
Published: May 2005

In stereoisomeric aryl cyclopropyl sulphones the 13C chemical shifts for C‐3 vary, while C‐1 and C‐2 are unaffected, on changing from the cis‐ to the trans‐configuration. The δC values of C‐1 of one of the aryl rings are shifted upfield in cis‐isomers and these values, together with those of C‐3, are used diagnostically to assign the molecular configurations.
1H and 13C NMR spectra of several (E)‐ and (Z)‐aldonitrones
Authors: Inouye Yoshinobu , Takaya Kazuharu , Kakisawa Hiroshi
Published: May 2005

The 1H and 13C NMR spectra were assigned for a series of N‐alkyl‐α‐methoxycarbonylmethanimine N‐oxides and N‐methyl‐α‐phenyl‐,N‐methyl‐α‐(pentamethylphenyl)‐ and N‐phenyl‐α‐benzoyl‐methanimine N‐oxides. Data are presented which allow the assignment of their configurations.
Conformational preference of substituted naphthalenes 3—derivatives of methoxy‐ and acetyl‐naphthalene
Authors: Salman Salman R.
Published: May 2005

Proximate coupling between methyl and ring protons is used to deduce the conformational preference of 1‐methoxynaphthalene (1), 2‐methoxynaphthalene (2) and 1‐acetylnaphthalene (3). Molecular orbital calculations at the CNDO/2 and INDO levels are used to calculate the energy and proton‐proton coupling constants in 1, 2 and 3.
Improvement of the two‐dimensional INADEQUATE technique by a ‘double selection’ experiment
Authors: Piveteau D. , Delsuc M. A. , Guittet E. , Lallemand J. Y.
Published: May 2005

The two‐dimensional NMR INADEQUATE pulse sequence allows unambiguous determination of spin‐spin connectivities, especially for dilute spins such as 13C, through the double‐quantum transitions of the spin system. A development of the sequence is presented which allows sign‐sensitive detection in the F1 dimension. The selection is obtained at two distinct stages, creation and observation of the double‐quantum transitions. The originality of the proposed sequence consists in a simultaneous modification of the traditional phase programme and pulse angles. A judicious choice of pulse phases is shown, both theoretically and experimentally, to activate the third pulse; modification of its value can then improve the selectivity of the experiment.
Application of biosynthetic 13C enrichment using [1,2‐13C2] acetate as precursor for 13C NMR spectral assignment of the isopropyl methyls of (24β)‐ethylsterols
Authors: Nicotra Francesco , Ronchetti Fiamma , Russo Giovanni , Toma Lucio , Ranzi Bianca M.
Published: May 2005

The resonances of C‐26 and C‐27 in the 13C NMR spectra of two (24β)‐ethylsterols, poriferasterol and clionasterol, were unambiguously assigned through a biosynthetic experiment from [1,2‐13C2]acetate in the chrysophyte Ochromonas malhamensis; the conclusion that the hydride migration from C‐24 to C‐25 during the biosynthesis of phytosterols occurs in most cases on the si‐face of the 24‐double bond precursor is experimentally established.
Carbon‐13 NMR spectra of dispiro compounds: Effect of homologation on chemical shifts of spiro carbons
Authors: Seth Neelima M. , Bhaduri A. P.
Published: May 2005

A comparative study of the 13C NMR spectra of derivatives of 14‐alkoxy‐ and 14‐hydroxy‐14‐azadispiro[5.1.5.2]pentadec‐9‐ene‐7,15‐diones and 12‐alkoxy‐and 12‐hydroxy‐12‐azadispiro[4.1.4.2]tridec‐8‐ene‐6,13‐diones has been carried out to establish the effect of homologation on the chemical shift of the twospiro carbons in the former class of compounds. Of the two spiro carbons of the derivatives of 14‐alkoxy‐14‐azadispiro[5.1.5.2]pentadec ‐ 9 ‐ ene ‐ 7, 15 ‐diones C‐8 was found to have experienced a greater shielding effect on homologation than the spiro carbon C‐6.
14N NQR study of the effect of protonation on the charge distribution of some N‐methylated ureas
Authors: Murgich Juan , Santana R. Magaly , Abanero José
Published: May 2005

The 14N NQR frequencies measured at 77 K for the amine group of the 1:1 salts of nitric acid with methylurea and 1,3‐ and 1,1‐dimethylurea and the phosphoric acid salt of 1,3‐dimethylurea are reported. The analysis of the NQR data showed that the N loses population from its π orbital. The decrease in π population is partially compensated by an increase in the population of the NC σ bonds. The loss of π population is enhanced when the H atoms of the amine group are substituted by electron‐donating groups such as CH3.
Analysis of internal rotations and rotational diffusion of N,N‐dimethyl‐1‐pyrenecarboxamide in CDCL3 solution
Authors: Gryff‐Keller A. , Poppe L.
Published: May 2005

The equilibrium conformation of N,N‐dimethyl‐1‐pyrenecarboxamide in CDCl3 solution has been deduced and the internal rotation rates around all single bonds, as well as the overall reorientation, have been characterized using dynamic NMR and 1H, 13C and 14N relaxation measurements.
1H nuclear magnetic resonance of α‐hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) and the α‐, β‐, γ‐ and δ‐polymorphs of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX)
Authors: Landers A. G. , Apple T. M. , Dybowski Cecil , Brill T. B.
Published: May 2005

1H NMR spectra of the energetic materials α‐hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) and the α‐, β‐, γ‐ and δ‐polymorphs of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) have been obtained in the solid phase. Primary and secondary dipole‐dipole interactions can be observed, which allows calculation of the intramolecular H …︁ H distances. The spectra suggest that γ‐HMX, the molecular structure of which is unknown, possesses a chair‐chair ring conformation similar to that of α‐ and δ‐HMX.
Assignment of quaternary carbons via two‐bond heteronuclear selective NOE difference, a useful structure elucidation aid
Authors: Sánchez‐Ferrando Francisco
Published: May 2005

Very low power irradiation of suitable narrow peaks in the proton frequency range generated NOE enhancement in neighbouring quaternary carbons, positioned two bonds from the irradiated protons. Subsequent FID acquisition under normal broad band decoupling yielded the NOE‐containing FID, which, after subtraction of the unperturbed broad band decoupled FID (devoid of NOE), gave the final NOE difference FID to which only the carbons undergoing NOE enhancement had contributed. Fourier transformation of the latter gave the NOE difference spectrum, usually a one‐ or two‐peak spectrum. This technique proved particularly useful for polysubstituted aromatic rings.
Carbon‐13 and platinum‐195 spin‐lattice relaxation times of tetrabutylammonium pyridinetrichloroplatinate(II)
Authors: Lystbaek K. , Bildsøe H.
Published: May 2005

13C and 195Pt spin‐lattice relaxation times, T1, have been determined for tetra‐n‐butylammonium trichloro‐pyridineplatinate(II) in different solvents. Correlation times for internal rotation around the PtN bond and for the overall motion are calculated based on a two‐site random jump model for the internal rotation. The results indicate that the ion pair forms molecular aggregates or stacks in low dielectric solvents. 13C Ti values for tetra‐n‐butylammonium trichloro(2‐propylpyridine)platinate(II) indicate that internal rotation around the PtN bond also takes place in this compound.
Expectation ranges of 13C NMR chemical shifts
Authors: Bremser W.
Published: May 2005

A table representing the chemical shift ranges for all carbon atoms with varying α‐substituents (one sphere HOSE codes) has been generated from a collection of 58 000 reference spectra, providing an overview of the influence of substitution on 13C NMR chemical shifts.
Carbon‐13 and hydrogen NMR data for a series of 1,4‐benzodiazepines
Authors: Scahill Terrence A. , Smith Stanford L.
Published: May 2005

Hydrogen and carbon chemical shifts and H‐H and C‐H couplings are reported for five simple 1,4‐benzodiazepines, three imidazolo‐1,4‐benzodiazepines, two modified triazolo‐1,4‐benzodiazepines.
Unusual 13C/77se couplings in the 13C NMR spectra of selenoimidates
Authors: Meese Claus O. , Walter Wolfgang
Published: May 2005

The 13C NMR. chemical shifts of several selenoimidates (3) are reported in comparison with imidates (1) and thioimidates (2). Distinct resonance signals of 3 show additional satellites arising from 77Se couplings. Extremely large three‐bond couplings [3J(13C77Se) = 28–39 Hz] are observed in the Z configuration of the N‐methylselenoimidate double bond, where the coupling nuclei (77SeCN13C) are cis‐orientated.
1H NMR spectra of various methylangelicins
Authors: Manzini Paolo , Rodighero Paolo , Pastorini Giovanni , Guiotto Adriano
Published: May 2005

A full analysis of the 1H NMR spectra of angelicin (2H‐furo[2,3‐h]‐l‐benzopyran‐2‐one) and of 25 of its mono‐, di‐ and tri‐methyl analogues, allows the assignments of all the peaks in the spectra to be made with reasonable certainty. Coupling constants have also been utilized in order to provide a better fit of the data.
Nitrogen‐15 NMR study of some barbituric acid derivatives
Authors: Nieminen Antti O. K. , Rautio Marjatta , Rahkamaa Erkki
Published: May 2005

The 15N chemical shifts and the one‐, two‐ and three‐bond 15N‐1H spin‐spin coupling constants for ten unenriched barbituric acid derivatives have been measured at 10.14 MHz in dimethyl sulphoxide‐d6. The measured 15N chemical shifts are in three distinct ranges: −270 to −280 ppm for urea‐type nitrogens, approximately −264 ppm for amide‐type nitrogens and between −226 and −236 ppm for imide‐type nitrogens, in accord with the gradually increasing possibility for delocalization of the nitrogen lone‐pair electrons. The 2 ppm shielding effect of the side‐chain hydroxy group, together with the 5 ppm shielding effect of the N‐methylation on the ring nitrogens, allows the identification of the diastereoisomers of 5‐allyl‐5‐(2‐hydroxypropyl)‐1‐methyl‐2,4,6(1H,3H,5H)‐pyrimidinetrione. The three‐bond coupling constant of 1.5 ± 0.2 Hz found in five compounds is a unique example of pure trans‐type spin‐spin coupling over an NCONH path. This study shows that particular attention must be paid to sample preparation and measuring conditions in order to achieve structurally significant nitrogen chemical shift and coupling information.
Interpretation of polar aromatic solvent‐induced shifts by means of the multipole approximation model
Authors: Nikki Kunio , Nakagawa Naoya
Published: May 2005

The aromatic solvent‐induced shifts (ASIS) of various polar solutes induced by polar and non‐polar aromatic solvents were determined. The protons that produce a large ASIS in non‐polar solvents show a remarkable depression of the ASIS in highly polar aromatic solvents. The observed ASIS in polar aromatic solvents are in good agreement with the calculated ASIS based on the electrostatic interaction between solute and solvent molecules.
Mechanism of epimerization of 2,3‐erythro‐aldoses to 2,3‐threo‐Aldoses: An NMR study
Authors: Lee Albert W. M.
Published: May 2005

Proton NMR spectroscopic studies on the conversion of 2,3‐erythro‐aldoses to 2,3‐threo‐aldoses in methanolic K2CO3 solution revealed the formation of the hemiacetals of the corresponding aldehydes, which probably provided the driving force of the easy epimerization.
13C1H Coupling Constants in Fluoropyridines
Authors: Yu. Denisov A. , Mamatyuk V. I. , Shkurko O. P.
Published: May 2005

The proton‐coupled 13C NMR spectra of 2‐, 3‐ and 4‐fluoropyridines were completely analysed and the signs and magnitudes of the 13C‐1H coupling constants determined. The root mean square deviations of the observed J(CH) values from those calculated using empirical correlations between the coupling constants in monosubstituted pyridines and benzenes were found to be 0.90 Hz for 1J(CH) and less than 0.26 Hz for the other nJ(CH) couplings.
NMR study of sesquiterpenes of the helenalin and parthenin series
Authors: Díaz E. , Domínguez G. G. , Mannino A. , Negrón G. , Jankowski K.
Published: May 2005

The assignment of the proton and carbon spectra of some cyclopropane sesquiterpene lactone derivatives of helenalin and anhydroparthenin is presented. The interpretation of the spectra was achieved using 1H‐13C two‐dimensional heteronuclear chemical shift correlation, proton two‐dimensional homonuclear correlated 2D and 2D‐J, and some classical techniques. In particular, the spectra of halocyclopropane derivatives are discussed and compared with the spectra of the parent sesquiterpenes.
Proton magnetic resonance studies of substituted 3,5‐dimethylbenzenes: Influence of substituents on the methyl proton chemical shifts
Authors: Kamounah Fadhil S. , Al‐Sheibani Ikbal. S. , Shibaldain Nazar L. , Salman Salman R.
Published: May 2005

Proton NMR data for a number of 1‐X‐4‐Y‐3,5‐dimethylbenzenes and 1‐X‐2‐Y‐4‐Z‐3,5‐dimethylbenzenes are presented. The proton chemical shifts of the methyl groups at positions 3 and 5 are mainly affected by the ring current effect of the substituents. This conclusion was strongly supported by the proton chemical shifts calculated using additivity rules.
One‐ and two‐dimensional nuclear overhauser effect. Investigation of the stereochemistry of 5‐functionalized 2‐imidazolines
Authors: Marsura A. , Luu‐Duc C. , Nardin R.
Published: May 2005

The study of 5‐functionalized 2‐imidazolines by 1H NMR, 1‐D NOE and 2‐D NOE is reported. The application of these methods confirms the relative configurations and conformations of the compounds. In particular, NOE effects and related crystallographic data are in good agreement with the proposed angular geometry of the N‐1 and the ring. Some examples of spectra obtained with the different techniques are presented and discussed.
1H Assignments of glycopeptide antibiotics by double quantum NMR and relayed correlation spectroscopy
Authors: Fesik Stephen W. , Perun Thomas J. , Thomas Alford M.
Published: May 2005

Two‐dimensional double quantum NMR and relayed correlation spectroscopy were used to complete the 1H assignments of a series of glycopeptide antibiotics. The double quantum NMR experiments were particularly useful in assigning the complicated aromatic region of the spectra by identifying the coupled protons with small differences in chemical shifts, and simplifying the contour maps by selectively enhancing the cross‐peaks corresponding to either the ortho‐(J≈8 Hz) or meta‐(J≈2 Hz) coupled protons. In addition, from the double quantum NMR experiments, protons belonging to the same spin system were unambiguously identified, even though not directly coupled. The connectivities between remote nuclei belonging to the same network were also established through relayed correlation spectroscopy.
Investigation of the amide rotation in N,N‐dialkylbenzamides. 7–Re‐examination of the role of the hydrogen bond in 2‐mercapto substituted derivatives
Authors: Gryff‐Keller Adam , Szczeciński Przemysław
Published: May 2005

Barriers to the amide rotation in 2‐mercapto‐N,N‐dialkylbenzamides [alkyl = CH3 or CH(CH3)2] and some of their derivatives were measured by dynamic 1H NMR. For N,N‐diisopropylamides, barriers to rotation about the carbonyl–aryl bond were also determined. The results show that the intramolecular hydrogen bond has only a very small influence on the measured barriers. In contrast to the literature data, only one set of signals, common to all possible forms of 2‐mercapto‐N,N‐dimethylbenzamide, has been observed.
Complete Assignments of the 13C NMR Spectra of Bilirubin‐IXα and its Dimethyl Ester
Authors: Müller Norbert
Published: May 2005

Using two‐dimensional heteronuclear 1H‐13C chemical shift correlation spectroscopy via one‐bond and long‐range couplings, all 13C resonances of bilirubin‐IXα and its dimethyl ester in dimethyl sulphoxide solution are assigned, independently from reference to partial structures. Previous ambiguities in the methyl regions of the 1H NMR spectra of these compounds are also resolved.
Asymmetry parameters of the electric field gradient at the 35Cl nuclei in compounds of the XC6H4CH2Cl series (X = CH3, Cl)
Authors: Feshin V. P. , Dolgushin G. V. , Voronkov M. G. , Sapozhnikov Yu. E. , Jasman Ya. B. , Popova E. P.
Published: May 2005

The asymmetry parameters of the electric field gradient at the 35Cl nuclei in polycrystalline compounds of the 2‐, 3‐ and 4‐XC6H4CH2Cl (X = CH3, Cl) series were measured at 77 K. The data obtained directly indicate the almost axial symmetry of the electric field gradient at the 35Cl nuclei, and the participation of the pσ electrons of the chlorine atom of the CICH2 group in the interaction with the geminal sp2 carbon atom in the molecules studied.

The experimental η values allow a more precise assignment of the lines in the NQR spectrum of 3‐ClC6H4CH2Cl.
Application of two‐dimensional correlated NMR techniques to the structure elucidation of 1‐methoxy‐endo‐tetracyclo[6.3.0.02,11.03,7]‐ undec‐9‐ene
Authors: Kruk C. , Jans A. W. H. , Cornelisse J. , Lugtenburg J.
Published: May 2005

By means of 500 MHz 1H two‐dimensional correlated NMR spectroscopy and the 62.89 MHz 13C two‐dimensional Inadequate technique, all proton and carbon chemical shifts of 1‐methoxy‐endo‐tetracy‐clo[6.3.0.02,11.03,7]undec‐9‐eene can be assigned in an unambiguous way.
Fractional populations of individual conformers in multidihedral systems: A J coupling constant approach
Authors: Barone Vincenzo , Lelj Francesco , Abbate Giancarlo
Published: May 2005

The use of J coupling constants in determining the conformational states of flexible molecules is analysed. A general model is developed which allows a complete specification of the molecular conformation, taking into the proper account the coupling between different dihedral angles. The number of joined fractional populations to be determined increases dramatically with the number of coupled dihedral angles, but it can be substantially reduced by a reasonable partitioning of the potential. An illustrative example is fully developed to show that a simple analysis of forbidden sequences of staggered conformations allows a reliable solution in the case of two coupled internal rotations.
Carbon‐13 chemical shift assignment of some organophosphorus compounds. IV—2‐oxo‐ and 2‐thio‐2‐phenoxy‐1,3,2‐diazaphosphorinanes and related P(IV) compounds
Authors: Al‐Rawi Jasim M. A. , Behnam George Q. , Ayed Naceur , Kraemer R.
Published: May 2005

Carbon‐13 chemical shifts and J(POC) and J(PNC) values have been determined for a series of substituted 2‐oxo‐ and 2‐thio‐2‐phenoxy‐1,3,2‐diazaphosphorinanes and related P(IV) compounds. 31P and 1H NMR were used in conjunction with 13C NMR spectra to establish some aspects of the stereochemistry of these compounds. 3J(PNCC) and 3J(POCC) seem to be more sensitive to the stereostructure than the 13C chemical shifts.
Enantiomeric purity of chiral metal carbonyl complexes using Eu(hfc)3
Authors: Solladié‐Cavallo A. , Suffert J.
Published: May 2005

It is shown that the enantiomeric purity of metal carbonyl complexes bearing an aldehyde group can be determined using Eu(hfc)3 and 200 MHz 1H NMR spectroscopy. A correlation between the chemical shifts and the absolute configuration is proposed in the case of the chromium tricarbonyl complexes.
13C NMR spectra of aryl‐substituted spirocyclopropanes
Authors: Abdel‐Wahab A. , Doss S. H. , Dürr H. , Spang P.
Published: May 2005

The 13C NMR spectra of 2‐arylspiro[cyclopropane‐1,9′‐thioxanthene S,S‐dioxides], 1–5, and 2′‐aryl‐spiro[10,11‐dihydro‐5H‐dibenzo[a,d]cycloheptene‐5,1′‐cycyclopropanes], 6–9, are described, and the effects of substituents are discussed. The relationship between the 13C shifts and the Hammett σ constants of substituents on the phenyl ring is not linear for 1–5. For 6–9 the chemical shifts of the cyclopropane carbons (C‐2′ and C‐3′) correlate reasonably well with electron density.
Stereochemical studies of tetracycline antibiotics and their common impurities by 400 MHz 1H NMR spectroscopy
Authors: Casy A. F. , Yasin Ahmed
Published: May 2005

The 400 MHz 1H NMR spectra of hydrochlorides of tetracycline, chlortetracycline, doxycycline and two epimeric derivatives are reported and interpreted in terms of solute conformation in DMSO‐d6 and configuration. Coupling constant magnitudes within the system H‐5, H‐4a, H‐4 and H‐12a and dimethylamino chemical shifts are applied to the configurational assignment of isomeric α‐ and β‐apooxytetracyclines.
13C NMR spectra of 2‐amino‐4H‐pyran derivatives
Authors: Pascual Conrado , Martin Nazario , Seoane Carlos
Published: May 2005

The 13C NMR spectra of sixteen 2‐amino‐4H‐pyran derivatives, consisting of seven 3‐cyano, two 5‐cyano and seven 3,5‐dicyano derivatives, are reported. For the purposes of comparison, 13C NMR data for 2,6‐dimethyl‐3,5‐dicyano‐4‐phenyl‐4H‐pyran are also given.
13C nuclear magnetic resonance spectra of bridged‐ring steroids and related compounds
Authors: Winnik Françoise M. , Yates Peter
Published: May 2005

Assignments of the 13C NMR signals of a series of bridged‐ring steroids incorporating a bicyclo [2.2.1] heptane system into ring A or B have been made on the basis of comparisons of their spectra with those of related unbridged steroids and bicyclo[2.2.1] heptane derivatives.
Data reduction by double forward fourier transformation
Authors: Roth K. , Kimber B. J.
Published: May 2005

By application of two successive forward Fourier transformations to an original free induction decay, the number of data points can be reduced by a factor of two without losing information.
13C NMR spectra of some mesoionic 1,2,3‐triazoles
Authors: Tsoleridis C. A. , Alexandrou N. E.
Published: May 2005

The 13C NMR spectra of three mesoionic 1,2,3‐triazol‐4‐ylacetamides and two 1,2,3‐triazol‐4‐ones were determined, and an evaluation of the shifts in relation to their mesoionic structure was made. A linear correlation between the 13C resonances and net charge densities, calculated by the CNDO/2 method, was obtained.
Carbon‐13 NMR of some organophosphorus compounds. 5‐2‐oxo‐ or 2‐thio‐2‐, 3‐, 4‐, 5‐, or 6‐substituted 1,3,2‐oxazaphosphorinanes and related P(IV) compounds
Authors: Al‐Rawi Jassim M. A. , Ayed Naceur , Kraemer Raymond , Navech Jacques
Published: May 2005

The 13C chemical shifts and PC coupling constants of nine 2‐oxo‐ or 2‐thio‐2‐, 3‐, 4‐, 5‐ or 6‐substituted 1,3,2‐oxazaphosphorinanes, with various groups attached to the ring carbon phosphorus and nitrogen atoms have been analysed. Some aspects of the stereochemistry of these compounds are verified.
31P chemical shifts and 31P—−13C coupling effects in the stereochemical analysis of benzo‐7‐phosphanorbornene derivatives
Authors: Quin Louis D. , Bernhardt F. Christian
Published: May 2005

The first phosphines based on the benzo‐7‐phosphanorbornene system have been prepared and found to have extremely deshielded 31P nuclei. The phosphine with a P‐tert‐butyl group gives the most downfield value (δ +152.5) ever recorded for a tertiary phosphine. The lone‐pair orientation in phosphines controls the magnitude of 2J (PC) and 3J (PC), and these effects were used to determine stereochemical features of the phosphines. These compounds were formed by HSiCl3pyridine reduction of the Diels—Alder adducts of isophosphindole oxides with norbornadiene. 13C NMR was also used to confirm the assignment of these phosphine oxides.
High‐field orientation effects in the high‐resolution proton NMR spectra of diverse porphyrins
Authors: Bothner‐By A. A. , Gayathri C. , van Zijl P. C. M. , MacLean C. , Lai Jan‐Ji , Smith Kevin M.
Published: May 2005

Dipolar splittings with a quadratic dependence on static magnetic field strength are reported for selected pairs of nuclei in several porphyrins. These splittings are detectable as a result of a slight molecular alignment caused by the interaction of the static magnetic field with the anisotropic magnetic susceptibilities of the porphyrin rings. The magnitude of the splitting yields an effective value for ΔX, the anisotropy of the susceptibility. This value includes association effects which may be estimated therefrom. Dipolar splittings between protons of attached vinyl groups can also be measured, and provide information about the average dihedral angle between the planes of the vinyl group and porphyrin ring.
1H, 3H and 13C NMR studies on porphobilinogen
Authors: Evans J. N. S. , Fagerness P. E. , Mackenzie N. E. , Scott A. I.
Published: May 2005

A key intermediate in porphyrin and corrin biosynthesis is the trisubstituted pyrrole porphobilinogen (PBG). The fate of PBG in the biosynthesis of porphyrins and corrins has been monitored by NMR spectroscopy in vivo and in vitro employing various nuclei. The syntheses of highly tritiated PBG and its immediate precursor 5‐aminolevulinic acid (ALA) are reported, together with 3H, 1H and 13C assignments.
The solution structure of lidocaine: Conformational analysis and NMR lanthanide‐induced shifts
Authors: Laplanche Laurine A. , Vanderkooi Garret , Jasmani Halila , Suki Maimunah Mat
Published: May 2005

Proton lanthanide‐induced shifts (LIS) were measured for Yb(fod)3—lidocaine complexes in CCl4 solution. The data were used in conjunction with empirical conformational energy calculations to determine the preferred conformations of lidocaine in complex with the lanthanide shift reagent. Energy calculations gave two pairs of symmetry‐related low‐energy conformations for lidocaine. The LIS analysis ruled out, on the basis of poor agreement factors, both members from one possible pair. This combination of methods therefore yielded two low‐energy, good agreement factor, symmetry‐related conformations for lidocaine in solution. These two conformations differ significantly from the reported crystal structure of lidocaine hydrochloride in the value of the NCOCH2N dihedral angle.
Through‐space 19F,19F spin—spin coupling constants in some fluoroallyl cations
Authors: Bakhmutov V. I. , Galakhov M. V. , Fedin E. I.
Published: May 2005

The 4J (19F19F) spin—spin coupling constants in some fluoroallyl cations are discussed. The through‐space contribution to the total spin—spin coupling constant for proximate 19F nuclei is obtained, and the dependence of this contribution on the internuclear distance is defined.
Deuterium isotope effects on 14N and 15N nuclear shielding in simple nitrogen‐containing compounds
Authors: Lyc̆ka Antonin , Hansen Poul Erik
Published: May 2005

Deuterium isotope effects on the 14N and 15N nuclear shielding of simple nitrogen‐containing compounds have been investigated. Very similar positive values for 1ΔN(D) have been observed in a series of amides and amines, excluding ammonium ions. Negative values of the deuterium isotope effect over three bonds are observed in acetonitrile and acetanilide. Both coaxial tube and single tube methods have been used, and show comparable results. The additivity of isotope effects over one bond is found to hold for ammonium compounds and amides. Solvent effects were investigated and are shown to be important. The origin of the solvent effects is ascribed to hydrogen bonding.
Carbon—carbon coupling constants derived from biosynthetic studies
Authors: Horak R. Marthinus , Steyn Pieter S. , Vleggaar Robert
Published: May 2005

The published data up to 1984 on carbon‐carbon coupling constants derived from biosynthetic studies are presented. Nearly 1400 one‐, two‐, and three‐bond carbon‐carbon coupling constants, representing 212 compounds are arranged in three Tables. In the first Table the compounds, together with their J (CC) values, are arranged according to their biosynthetic origin. In the second Table couplings over more than one bond are collected. The one‐bond couplings are arranged in Table 3, in order of increasing magnitude in each of six categories which, in turn, are based on the formal hybridisation of the coupled carbon atoms. This method of categorisation provides direct access to a vast amount of biosynthetic information and allows the estimation of typical ranges for the various types of (C,C) coupling constants. The magnitude of the carbon‐carbon couplings is discussed in terms of factors such as the electronegativity of the substituents, ring size and stereochemical influences. In addition, the applications of carbon‐carbon coupling in biosynthetic studies, as well as the experimental methods for obtaining these values, are discussed.
The structure of thialene as studied by proton magnetic resonance in a nematic phase
Authors: Suryaprakash N. , Khetrapal C. L. , Klein R. F. X. , Horak V.
Published: May 2005

1H NMR studies on thialene (cyclopenta[b]thiapyran) oriented in a nematic liquid crystalline phase are reported. The indirect spin‐spin and direct dipolar couplings and the chemical shifts between the protons are derived from the spectral analysis. The intra‐ring proton‐proton indirect couplings derived from the isotropic and nematic phase spectra are in agreement. The inter‐ring proton‐proton couplings, however, could only be obtained from the nematic phase spectra. The structural information extracted from the direct dipolar couplings corresponds to significant distortions in the arrangement of the protons of the six‐ and five‐membered rings from the regular hexagonal and pentagonal arrangements, respectively; the molecular geometry of the fused five‐membered ring is similar to that of the corresponding ring in azulene.
Intramolecular van der Waals interactions and 13C chemical shifts: Substituent effects in some cyclic and bicyclic systems
Authors: Li S. , Chesnut D. B.
Published: May 2005

In recent work, a reasonably good linear correlation was found to exist between the local van der Waals steric energy as calculated by the MM2 force field and the chemical shift of the resonant nucleus within classes of saturated aliphatic phosphines, amines, hydrocarbons and monofunctional alcohols. This study extends this work to some additional cyclic systems: 91 trans‐ and 31 cis‐decalin carbons, 57 bicyclo[2.2.1]heptane and 27 bicyclo[2.2.2]octane nuclei have been investigated and yield root‐mean‐square errors of 3.3–3.7 ppm and correlation parameters in good agreement with those found previously for other carbon species. In the more strained bicyclo systems it is found that additional class parameters must be defined. The theory is applied to a variety of α,β,γ,… ubstituents effects in cyclohexane and decalin systems, and correlated these resonant shifts under one simple, physical model.
Application of two‐dimensional NMR spectroscopy to the study of the cyclic decapeptide antamanide
Authors: Giralt Ernest , Feliz Miguel
Published: May 2005

The 1H and 13C NMR spectra of antamanide were analysed by using the concerted application of two‐dimensional (2D) homocorrelated (1H1H) and heterocorrelated (13C‐1H) spectroscopy. Through these experiments it was possible to confirm the assignment of many of the 1H and 13C NMR signals of antamanide and, in addition to provide further assignments. The temperature coefficients of all the NH resonances were calculated by comparing 2D spectra obtained at different temperatures.
Concerted use of homo‐ and hetero‐nuclear 2D NMR: 13C and 1H assignment of sucrose octaacetate
Authors: Nishida Toshiaki , Enzell Curt R. , Morris Gareth A.
Published: May 2005

The complete assignment of the sugar and acetate 13C and 1H signals of sucrose octaacetate by homo‐ and hetero‐nuclear 2D NMR is described, using the Jeener (COSY) and relayed coherence transfer techniques and heteronuclear shift correlation via both one‐bond and long‐range couplngs.
1H and 13C NMR studies on 2‐aminofluorene derivatives with carcinogenic and mutagenic activities
Authors: Nicoletti M. , Iorio M. A.
Published: May 2005

1H and 13C NMR spectroscopy were utilized for the identification of carcinogenic and mutagenic N‐hydroxy(acyloxy)‐2‐acetylaminofluorenes, and the inactive products derived from their thermal/enzymatic rearrangement involving N→C‐1/C‐3 migration of the hydroxy (acyloxy) group.
13C and proton nuclear magnetic resonance spectra of trans‐[arylbromobis(triethyl phosphine)palladium(II)] and related compounds. The π‐donor ability of the Ni(PEt3)2X, Pd(PEt3)2X and Pt(PEt3)2X groups
Authors: Granell Jaume , Muller Guillermo , Rocamora Mercè , Vilarrasa Jaume
Published: May 2005

13C and proton NMR spectra of several arylpalladium and some arylnickel and arylplatinum complexes have been compared. The Ni(PEt3)2X and Pd(PEt3)2X substituents induce a paramagnetic shift of Cipso (of the phenyl ring) which is much larger than that induced by Pt(PEt3)2X. However, there are no significant differences along the Ni/Pd/Pt series for the ortho, meta and para positions. For the six compounds of general formula trans‐[ArPdBr(PEt3)2] reported here, the mean Δ(δ)C values induced on the ArH by the introduction of the PdBr(PEt3)2 substituent are found to be 26.9 (Cipso), 7.2 (Cortho), −1.1 (Cmeta), −5.5 (Cpara), −0.03 (Hortho), −0.28 (Hmeta) and −0.38 ppm (Hpara).
The use of 13C satellites in the proton NMR spectra of oriented systems for the determination of molecular structure
Authors: Suryaprakash N. , Khetrapal C. L.
Published: May 2005

The use of the 13C satellites in the proton NMR spectra of systems providing deceptively simple spectra is suggested and demonstrated for the determination of molecular geometry using NMR spectroscopy of oriented systems. The rα structure of phenyl isothiocyanate has thus been determined. The spectrum without the 13CH satellites does not provide sufficient independent dipolar couplings to determine the relative arrangements of protons and the order parameters.
Sequential assignments in deoxyribonucleotide tetramers by 31P/1H two‐dimensional shift correlation NMR spectroscopy
Authors: Otter Albin , Lown J. William , Kotovych George
Published: May 2005

The potential of two‐dimensional 31P/1H shift correlation NMR spectroscopy is demonstrated on three self‐complementary oligodeoxyribonucleotides: [d(CpGpCpG)]2, [d(ApCpGpT)]2 and [d(ApGpCpT)]2. The usefulness of this experiment for the sequential assignments of the nucleotides as a complementary technique to homonuclear shift correlation procedures (e.g. COSY) is outlined. The complete 31P assignments for all three tetramers are given, and are compared with literature data obtained by different approaches. A surprising and, as far as we are aware, previously unreported property of the 4′‐protons in the sugar phosphate backbone is described.
Carbon‐13 chemical shift assignment of some organophosphorus compounds. II—bicyclic phosphoranes bearing a chiral pentacoordinated phosphorus and a chiral carbon atom
Authors: Al‐Rawi Assim M. A. , Ayed Naceur , Osman Ayez H.
Published: May 2005

Carbon‐13 chemical shifts and PC coupling constants of seven bicyclic phosphoranes[1‐alkyl or 1‐aryl‐2,8‐dioxa‐5‐aza‐1‐phospha(V)bicyclo[3.3.0]octanes] and their 3‐ and 6‐substituted bicyclic phosphoranes were verified using changes in the 13C chemical shifts and the J(PC) values.
Molecular structure determinations of BF3‐tetralone complexes by NMR spectroscopy
Authors: Torri J.
Published: May 2005

The 13C NMR shielding effects of the carbonyl‐BF3 interaction for a series of methyl‐ and methoxy‐tetralones were determined. Once the conformations of the complexes have been defined, the major shift data which can be related to charge density changes can be qualitatively discussed in terms of the transmission of the electronic properties of the CO:BF3 group. Complexation mainly causes a reorganization of the conjugated π‐system via a resonance mechanism. Delocalization of the π‐electrons towards the BF3 electron‐withdrawing group increases the carbonyl reactivity of the base, while complex stability is favoured.
13C NMR spectra of 7‐, 8‐, 9‐ and 10‐fluorobenzo[a]pyrene
Authors: Sardella D. J. , Boger E.
Published: May 2005

The 13C NMR spectra of 7‐, 8‐, 9‐ and 10‐fluoro‐benzo[a]pyrenes have been recorded and the chemical shifts of all protonated (and fluorine‐substituted) carbons have been assigned. The effect of fluorine on carbon shifts (and also on electron densities, which correlate reasonably well with the shifts) is confined largely to the fluorinated ring and contiguous sites, such as peri positions or carbons across bay regions. A variety of short‐ and long‐range couplings are observed, and correlations with π‐bond orders (two‐bond couplings) and ato n polarizabilities (one‐bond couplings) are observed. Long‐range coupling patterns are less obvious, but six‐bond couplings appear to correlate with atom‐atom polarizabilities, as expected for transfer of spin information through the π‐system.
13C and 1H NMR spectral studies of some piperidin‐4‐one oximes
Authors: Pandiarajan K. , Mohan R. T. Sabapathy , Hasan Misbah Ul
Published: May 2005

13C NMR spectra have been recorded for eleven piperidin‐4‐one oximes and for seven of them 1H NMR spectra have been recorded at 270 MHz. The effect of oximation on the NMR chemical shitts is discussed. The conformations of the oximes are also discussed, based on the observed chemical shifts. Although several oximes appear to adopt a chair conformation, in the same manner as the corresponding ketones, the oximes of 3,5‐dimethyl‐2,6‐diarylpiperidin‐4‐ones with cis‐methyl groups seem to adopt an asymmetric non‐chair conformation. Analysis of the chemical shifts of cis‐2,6‐dimethylcyclohexanone oxime suggests that this compound also exists in a non‐chair conformation, and not in a chair conformation with two axial methyl groups as suggested previously.
1H and 13C NMR spectra of pentafulvalene compared with selected pentafulvenes
Authors: Escher André , Bönzli Peter , Otter Albin , Neuenschwander Markus
Published: May 2005

The 1H NMR spectrum of pentafulvalene has been analysed. Proton‐proton coupling constants and 13C chemical shifts are compared with those of sterically similar pentafulvenes. Pentafulvalene can be regarded as a pentafulvene with a highly localized π‐system.
Chelate ring effects in 95Mo NMR spectroscopy
Authors: Alyea Elmer C. , Somogyvari Arpad
Published: May 2005

Ring contributions (δR) to the chemical shift in 95Mo NMR spectroscopy are defined for some molybdenum(0) complexes of chelating phosphine ligands. The chelate ring effect is greatest for five‐membered rings, with the 95Mo resonances being shielded by ca 120 ppm for the ditertiary phosphine complexes. Experimental estimates of δRR(95Mo) are also reported for five‐membered rings containing nitrogen and arsenic donor ligands.
13C NMR studies of 23‐norchol‐20(22)(E)‐enoic acid derivatives
Authors: Maier Marta S. , Seldes Alicia M. , Gros Eduardo G.
Published: May 2005

The 13C NMR spectra of a series of derivatives of 23‐norchol‐20(22)(E)‐enoic acids and their ethyl esters are reported.
Benzene‐induced 1H NMR shifts of flavone protons: Detection of H‐3
Authors: Vyas Ashok V. , Mulchandani Newand B.
Published: May 2005

Deuteriated benzene‐induced shifts [Δ ppm = δ(CDCl3)–δ(C6D6)] in the 1H NMR spectra of some naturally occurring polyoxygenated flavones isolated from Ageratum conyzoides and Eupatorium odoratum have been studied. The downfield shift of the pyrone ring proton H‐3, particularly in B‐ring methoxylated flavones, is significant; as it is in the opposite direction to that of an aromatic proton it could be of diagnostic value in structural elucidation. The benzene‐induced shifts of all the other protons have also been studied.
Nitrogen‐15 nuclear magnetic resonance studies of hydrogen bonding and proton transfer in some pyridine trifluoroacetates in dichloromethane
Authors: Dega‐Szafran Z. , Szafran M. , Stefaniak L. , Brevard C. , Bourdonneau M.
Published: May 2005

The 15N NMR chemical shifts of ten substituted pyridines (B) and their complexes with trifluoroacetic acid (AHB) were measured at the natural abundance level in dichloromethane. The plot of the relative chemical shifts [Δδ(15N)δ(AHB)δ(B)] against ΔpKa gives a titration curve which reflects a protometric equilibrium AH…B⇌A−…HB+. These data were used to determine the constants of the overall proton transfer reaction (Kexp). A linear relationship holds between log Kexp and ΔpKa. Δδ(15N) values can be treated as a good hydrogen bond parameter.
1H NMR study of Eu(fod)3–macrocyclic lactone systems
Authors: Cazaux L. , Picard C. , Tisnes P.
Published: May 2005

The effect of Eu(fod)3 on some 12–30‐membered macrocyclic lactones containing various basic sites was investigated in CDCl3 solution using 1H NMR spectroscopy. Apparent complexation constants Kc, and lanthanide‐induced shifts of the complexes were determined for an assumed 1:1 stoichiometry. In these macrocycles, the participation of the binding sites depends not only on their nature, but also on the ring size and on the conformational behaviour of the macrocycles. On the other hand, the equilibrium constant data clearly indicate that the ring size is the dominating factor in the stability of the Eu(fod)3–lactone system.
Comparison of the thiocarbonyl13C NMR resonances of N‐phenylthioureas, N‐phenyl thiocarbamates and N‐phenyl dithiocarbamates
Authors: Ares Jeffrey J. , Urchek Thomas G. , Palmer Charles W. , Miller Duane D.
Published: May 2005

13C NMR spectra of N‐phenylthioureas, N‐phenyl thiocarbamates and N‐phenyl dithiocarbamates of the ethyl and n‐butyl type are compared. Significant differences are observed in the chemical shift of the thiocarbonyl carbon, which do not parallel the electronegativity of the bonded heteroatom.