bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic NMR study of the electronic state of heteroaromatics. VIII. The influence of the exo‐ and endocyclic heteroatoms
Authors: Kleinpeter E. , Spitzner R. , Schroth W. , Philaja K. 
Published: May 2005

AbstractThe 1H/13C‐n.m.r. chemical shifts and rotational barriers for the exocyclic partial C,N‐double bonds of some pyran‐ (1–3) and thiopyranthiones 4 and 5 are discussed in relation to the π‐electron density in these strongly polar heteroaromatics.
Aromaticity as a Quantitative Concept. 2. Sixteen familiar five‐ and six‐membered monocyclic heterocycles
Authors: Katritzky Alan R. , Feygelman Vladimir , Musumarra Giuseppe , Barczynski Piotr , Szafran Miroslaw 
Published: May 2005

AbstractRestudy of an almost complete data set of 12 characteristics for 16 common heterocycles confirms the previous conclusion [1] of the independence of „classical”︁ and of „magnetic”︁ aromaticity. The scores for the individual heterocycles correlate well with their chemical structure.
Aromaticity as a Quantitative Concept. 3. Benzo‐fused five‐ and six‐membered heterocycles
Authors: Katritzky Alan R. , Feygelman Vladimir , Musumarra Giuseppe , Barczynski Piotr , Szafran Miroslaw 
Published: May 2005

AbstractA rather complete data set for 12 characteristics of 18 common benzo‐fused heterocycles yields two significant principal components. The loadings of the characteristics show a close correlation with those found for the same characteristics of monocyclic heterocycles. The scores for each bicycle are also closely related to those for the corresponding monocycle. The method demonstrates considerable predictive power.
Aza‐Enamine. IX. UV/VIS‐ und NMR‐spektroskopische Interpretation der Elektronenstruktur in Aldehydhydrazonen und daraus hergestellten Aza‐Trimethinen
Authors: Brehme Rainer , Radeglia Reiner , Gründemann Egon 
Published: May 2005

Aza‐Enamines. IX. UV/VIS and N.M.R. Spectroscopic Interpretation of the Electron Structure in Aldehyde‐N,N‐dialkylhydrazones and in Aza‐trimethines Prepared from TheseThe n.m.r. and u.v./vis spectroscopic data of the compounds 2, 3 and 4 – synthesized by electrophilic substitution at the azomethine carbon atom of the aldehyde hydrazones 1 according to the aza‐enamine‐concept – are reported. Compared to the respective C‐atom of the starting hydrazones 1 the azomethine‐C‐atom of the compounds 2–4 exhibits a 13C‐n.m.r. shift not corresponding to usual substituent effects. Our interpretation for this and for the u.v./vis spectroscopic data, too, is a simultaneous existence of both an aza‐trimethine structural unit and an aromatic structure in the compounds 2–4.
Zur Molekülverknüpfung mit Schwefelchloriden. IX. Reaktion von Schwefeldichlorid mit N‐Allyl‐anilinen. Eine Synthese für 2‐Chlormethyl‐2,3‐dihydro‐1,4‐benzothiazine
Authors: Mühlstädt M. , Hollmann K. , Möder M. 
Published: May 2005

Molecule Linkage by Sulfur Chlorides. IX. The Addition Reaction of Sulfur Dichlorides with N‐Allyl‐anilines. A Synthesis for 2‐Chloromethyl‐2,3‐dihydrobenzo‐1,4‐thiazinesReactions of different substituted N‐allyl‐anilines 1 with sulfur dichloride yield 2‐chloromethyl‐2,3‐dihydrobenzo‐1,4‐thiazines 3a–i. The identification of the products was carried out by mass spectroscopy and 1H‐n.m.r.‐spectroscopy. The seven‐membered cyclic isomers of the S, N‐heterocycles 3, dihydro‐benzo‐1,5‐thiazepanes 5 were not obtained.
N.M.R. Studies on Aminated Dinitrobenzofuroxan and Dinitrobenzofurazan Derivatives
Authors: Gründemann E. , Niclas H.‐J. , Göhrmann B. 
Published: May 2005

AbstractThe 13C‐n.m.r. chemical shifts of σ‐NC‐bonded Meisenheimer complexes 3, 5 and their corresponding aminated dinitrobenzofurazans 4 and dinitrobenzofuroxans 6 were determined. The chemical shifts are discussed as a function of electronic substituent effects.The assignment was performed by means of 1H13C coupling constants and by comparison with che 13C‐chemical shifts of appropriate model compounds. The 13C‐n.m.r. spectra of Meisenheimer tomplexes 3 reveal doubling of signals, indicating a hindered rotation at the NCHO bond.
Distribution of alkyl derivatives of 2‐hydroxybenzophenone oximes and aliphatic α‐hydroxyoximes in hydrocarbon‐water and their polarity parameters
Authors: Olszanowski Andrzej , Borowiak‐Resterna Aleksandra 
Published: May 2005

AbstractThe values of partition coefficient of 5‐alkyl‐2‐hydroxybenzophenone oxime derivatives and aliphatic α‐hydroxyketone oximes with various lengths of carbon chains were determined for toluene‐water and heptane‐water systems. The dimerization constants of alkyl 2‐hydroxybenzo‐phenone oxime derivatives in toluene and heptane, and the values of polarity parameters of aliphatic α‐hydroxyoximes were determined by gas chromatography. It was found that the partition coefficients of both groups of oximes decrease with decreasing length of the alkyl chain. The partition coefficients are higher for toluene‐water system than for heptane‐water system. A correlation exists between the partition coefficients and the polarity parameters of hydroxyoximes.
Synthese eines neuen Thienospirans: 6,7‐Dihydro‐1′‐methyl‐spiro[benzo[b]thiophen‐4(5H),2′‐piperidin]
Authors: Fröhlich Hannes , Gmeiner Günter , Sauter Fritz 
Published: May 2005

Synthesis of a New Thienospiran: 6,7‐Dihylro‐1′‐methyl‐spiro[benzo[j]thioxhen‐4(5H),2′‐piperidine]The title spiro compound 6 – a N‐methyl derivative of a new parent system ‐ has been synthesized from nitrile 8 via 4‐phenoxybutylation, followed by modified Schmidt degradation, ensuing O‐deprotection and final cyclization. The constitution of the target compound and of all intermediates is established by 1H‐n.m.r. and 13C‐n.m.r.‐spectroscopy and by microelementary analysis.
Organophosphorus chemistry. 16. The Reaction of Furfurylidenemalonitrile with Alkyl Phosphites
Authors: Abdou Wafaa M. , Khidre Maha D. , Mahran Mohamed R. 
Published: May 2005

AbstractDialkyl phosphites (2a–c) react with furfurylidenemalonitrile (1) to give the corresponding 1:1 phosphonate adducts 3a–c. On the other hand, trialkyl phosphites (6a, b) affected C‐alkylation of the exocyclic ethylenic linkage in compound (1) to give the respective phosphonate 7a, b.
Cyclocondensation of 4‐Benzyl‐1‐hydrazinophthalazine
Authors: El‐Feky Said , Bayoumy Bashner E. 
Published: May 2005

Abstract1‐Hydrazino‐4‐benzylphthalazine 1 underwent closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride, trifluoroacetic anhydride, ortho esteres, aldehydes, urea or carbon disulphide to afford the N‐formyl 3a, N‐acyl 3b, and the appropriate 3‐substituted‐6‐benzyl‐s‐triazolo [3,4‐a] phthalazines 4a, c, 7, 8. Alkylation of the obtained s‐triazolo[3,4‐a]‐phthalazine‐3‐thione 7 and s‐triazolo [3,4‐a] phthalazin‐3‐one 8 with N‐substituted chloroacetamides gave the thioether 9 and N‐substitution products 10, respectively. Likewise, applying Mannich conditions of the previously mentioned intermediates 7 and 8 yielded the N‐Mannich bases (11 and 12). The new products were characterized by their elemental and spectral data.
Reaction of Tetracyanoethylene with Arylazoaminopyrazoles via charge‐transfer complexation
Authors: Hassan Alaa A. , Ibrahim Yusria R. , Mohamed Nasr K. , Mourad Aboul‐Fetouh E. 
Published: May 2005

AbstractArylazoaminopyrazoles (1a–d) reacts with tetracyanoethylene (TCNE) to yield pyrazolo[1,5‐a]pyrimidines (9) via charge‐transfer (CT) complex formation. The effect of the substituents on the basicity of the pyrazole nucleus as well as the complexation centre in different types of pyrazoles is discussed.
Synthese von Cyclobutan durch Dehalogenierung von 1,4‐Dihalogenbutanen mit Alkalimetalldämpfen. Zur Relation von radikalischen und metallorganischen Reaktionskanälen
Authors: Volnina S. A. , Avakjan V. G. , Guselnikov L. E. , Al Yaya A. 
Published: May 2005

Synthesis of Cyclobutane by Dehalogenation of 1,4‐Dihalogenbutane in Alkali‐Metall‐Bathway. The Relation of Radical and Metallorganic Reaction‐channels.Gasphase dehalogenation of 1,4‐dichloro‐, 1‐chlor‐4‐bromo, 1,4‐dibrombutanes and 1,4‐dibrompentane by Na/K vapors produces cyclobutane resp. methylcyclobutane with selectivities of resp. 55.5, 46.7, 32.0 and 17 moles/100 moles. Side products of the reaction are ethylene and hydrogen, yields of which increase with increasing temperature and rising degree of substitution of chlorine by bromine. A mechanism is discussed in which the initiation step is the generation of halobutyl radicals of the type H2Ċ(CH2)2CH2X (X = Cl, Br) which are reacting further in two ways – by formation of tetramethylenediradical, splitting off the second halogen atom, or by the formation of the metallorganic compound 1‐kalium‐4‐halogenbutane, which further cyclisize to cyclobutane splitting off KX.Using some methods of theoretical chemistry such as quantumchemical calculations based on ab initio (STO‐3G) and semiempirical (AM1) structures, on the relative energies of conformeres of halogenbutylradicals and on models of the metallorganic intermediates, but also by conformation calculations of the content of rotation isomers of the intermediate formed, the correlation between the two reaction channels in dependence of the type of halogen was estimated. The calculations showed, that only about 20% of cyclobutane are generated by the radical pathway. The high predominance of the metallorganic channel in the case of 1,4‐dichlorbutaneis caused by the high lifetime of chlorobutyl radicals in comparison with his bromoanalogues.
Surface passivation of GaAs using a Ge interface control layer
Authors: Jishiashvili D. , Gobsch G. , Ecke G. , Gobronidze V. , Mtskeradze G. , Shiolashvili Z. 
Published: June 2005

AbstractThe effective surface passivation is a key to achieve useful metal–insulator–semiconductor devices on GaAs. In this work, the composition and structure of the pyrolytic GeOxNy film deposited on GaAs in the hydrazine vapour has been studied by Auger electron spectroscopy and transmission electron microscopy. The capacitance‐voltage characteristics was used to investigate the GeOxNy–GaAs interface in the frequency range of 1 kHz–1 MHz. The deposited insulator film has a layered structure and consists of a thin (∼2–4 nm) amorphous Ge interface control layer adjacent to the GaAs, followed by the outer GeOxNy film. It is found that a high quality interface is formed with the minimum interface state density of 3 × 1011 cm–2 eV–1 at midgap energies in GaAs. It is suggested that a good bond matching at the GaAs–Ge interface and coherent termination of bonds at both sides of the Ge interface control layer are the reason for perfect passivating properties of the GeOxNy film. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect study on deformed Fe–Si alloys by positron annihilation techniques
Authors: Agundez M. , Ruiz D. , Petegem S. Van , De Baerdemaeker J. , Chou K. W. , Segers D. , Houbaert Y. 
Published: June 2005

AbstractPositron annihilation lifetime and coincidence Doppler broadening measurements have been performed on ultra low carbon steel and Fe–Si alloys with different Si contents (from 3.32 up to 11.1 wt%) in the annealed state and after a deformation of 5% thickness reduction. It was seen that above 5.6 wt% Si the nature of the defects trapping the positron changes. This coincides with the concentration for the onset of long range D03 ordering in the Fe–Si alloys changing the nature of the dislocation structure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐step method for precise calculation of core properties in molecules
Authors: Titov A. V. , Mosyagin N. S. , Petrov A. N. , Isaev T. A. 
Published: May 2005

AbstractPrecise calculations of core properties in heavy‐atom systems that are described by the operators heavily concentrated in atomic cores, such as hyperfine structure and P,T‐parity nonconservation effects, require accounting for relativistic effects. Unfortunately, four‐component calculation of molecules containing heavy elements is very consuming already at the stages of calculation and transformation of two‐electron integrals with a basis set of four‐component spinors. In turn, the relativistic effective core potential (RECP) calculations of valence (spectroscopic, chemical, etc.) properties of molecules are very popular, because the RECP method allows one to treat quite satisfactorily the correlation and relativistic effects for the valence electrons of a molecule and to reduce significantly the computational efforts. The valence molecular spinors are usually smoothed in atomic cores, and, as a result, direct calculation of electronic densities near heavy nuclei is impossible. In this paper, the methods of nonvariational and variational one‐center restoration of correct shapes of four‐component spinors in atomic cores after a two‐component RECP calculation of a molecule are discussed. Their efficiency is illustrated in correlation calculations of hyperfine structure and parity nonconservation effects in heavy‐atom molecules YbF, BaF, TlF, and PbO. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Foundations of the relativistic theory of many‐electron bound states
Authors: Sucher J. 
Published: May 2005

AbstractMost of the existing calculations of relativistic effects in many‐electron atoms or molecules are based on the Dirac–Coulomb Hamiltonian HDC. However, because the electron–electron interaction mixes positive‐ and negative‐energy states, the operator HDC has no normalizable eigenfunctions. This fact undermines the quantum‐theoretic rationale for the Dirac–Hartree–Fock (DHF) equations and therefore that of the relativistic configuration‐interaction (RCI) and multiconfiguration Dirac–Fock (MCDF) methods. An approach to this problem based on quantum electrodynamics is reviewed. It leads to a configuration‐space Hamilton H which involves positive‐energy projection operators dependent on an external potential U; identification of U with the nuclear potential Vext corresponds to use of the Furry bound‐state interaction picture. It is shown that the RCI method can be reinterpreted as an approximation scheme for finding eigenvalues of a Hamiltonian H, with U identified as the DHF potential; the theoretical interpretation of the MCDF method needs further clarification. It is emphasized that if U differs from Vext one must consider the effects of virtual‐pair creation by the difference potential δU = Vext − U; an approximate formula for the level‐shift arising from δU is derived. Some ideas for dealing with the technical problems introduced by the projection operators are discussed and relativistic virial theorems are given. Finally, a possible scheme for adapting current MCDF methods to Hamiltonians involving projection operators is described.
Relativistic studies of atoms and ions with complex configurations
Authors: Rudzikas Z. B. 
Published: May 2005

AbstractThe method of the relativistic investigation of the energy spectra and the electronic transitions in the case of complex configurations, based on the theory of the irreducible tensorial operators and the genealogical coefficients, is described. The use of the quasispin and isospin technique in the relativistic approximation is discussed. Expressions are presented for electric multipole transition probabilities for general values of the gauge condition of electromagnetic field potential.
Relativistic calculation of autoionization widths of 1s2s2pjJ, 1s2s22S1/2, and 1s2pJ2pj′J levels
Authors: Safronova U. I. , Tsirekidze T. A. 
Published: May 2005

AbstractThe autoionization widths of levels 1s 2s 2pjJ, 1s2s2 2S1/2, and 1s2pj2pj′ J have been calculated for ions with Z = 6–30. The calculation has been carried out in intermediate coupling. The decay amplitudes have been calculated in a relativistic approximation.
Use of the S‐matrix in the relativistic treatment of resonance energy transfer
Authors: Avery John 
Published: May 2005

AbstractThe S‐matrix formalism is used to treat the phenomenon of resonance energy transfer (sensitized fluorescence). It is shown that for dipole‐allowed transitions and short sensitizer–acceptor separations, the relativistic treatment yields the same result as the nonrelativistic Perrin–Förster theory. For large sensitizer‐acceptor separations, long‐range coupling terms appear in the relativistic treatment. Resonance energy transfer through these long‐range coupling terms is compared with spontaneous photon emission, and direct‐interaction theories of electromagnetism are discussed. In the Appendix it is shown that the relativistic theory predicts resonance transfer of triplet excitation energy through the spin–spin coupling term in the Breit interaction.
Self‐consistent Dirac–Slater calculations for molecules and embedded clusters
Authors: Ellis D. E. , Goodman G. L. 
Published: May 2005

AbstractThe basis of self‐consistent local density theory used in the fully relativistic Dirac–Slater model is briefly reviewed. Moment‐polarized extensions of theory are developed to treat open‐shell systems by lifting the pair‐wise Kramers degeneracy. The discrete variational method is used to calculate one‐electron energies and charge and magnetization densities of a series of rare‐earth trihalides. The theoretical binding energies compare very well with recent gas‐phase photoelectron spectra of Berkowitz et al. The von Barth–Hedin exchange and correlation potential produces energies which are significantly better, compared to simpler exchange‐only models. Embedded molecular cluster studies on actinide compounds are reported, with particular emphasis on the AcO2 dioxides. Single‐particle energy densities of states (DOS) and magnetization DOS are presented, along with an analysis of effective atomic configurations in the solid. Trends in these quantities with actinide atomic number are noted. In contrast to the semicore nature of rare‐earth 4f electrons, the actinide 5f levels are seen to be active participants in bonding interactions.
Spin‐orbit excitation in the system I + I2: Relativistically parameterized extended‐Hückel calculations
Authors: Viste A. , Pyykkö P. 
Published: May 2005

AbstractRelativistically parameterized extended‐Hückel (REX) calculations concerning species and exchange reactions in the system I or I* + I2 are reported, where I = 2P3/2 and I* = 2P1/2. From their experimental data for related halogen systems X + YZ XY + Z, E. B. Gordon, A. I. Nadkhin, S. A. Sotnichenko, and I. A. Boriev [(Chem. Phys. Lett. 86, 209 (1982)] have proposed a conservation rule for the spin‐orbit state (X* → Z*, X → Z). The results of REX calculations, double‐group symmetry analysis, and schematic state correlation diagrams reported here are consistent with the proposed conservation rule. Two of the transition states are linear and the third nearly so, but no Γ1/2–Γ3/2 crossings leading to spin‐orbit conversion are found.
Relativistic band structure calculations
Authors: Christensen N. Egede 
Published: May 2005

AbstractThe inclusion of relativistic effects in band theory is discussed. Examples showing how these affect optical properties, Fermi surface properties, and cohesive properties are shown. With respect to the latter, it is pointed out that the mass–velocity and Darwin shifts are most important, whereas the SO coupling can be omitted since it does not shift the bands (quenching of angular momentum). The band theoretical aspects are presented in the terminology of the LMTO‐ASA method which offers a physical transparent picture of the formation of bands. The volume and energy dependences of the spin‐orbit splittings are explained in this picture. As examples are considered calculations for W, Xe, Au, and the copper halides.
Interaction of O2, CO and CO2 with Co films
Authors: Frerichs M. , Schweiger F. X. , Voigts F. , Rudenkiy S. , Maus‐Friedrichs W. , Kempter V. 
Published: May 2005

AbstractMetastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS(HeI)) and x‐ray photoelectron spectroscopy (XPS) were applied to study the interaction of O2, CO and CO2 with Co films at room temperature. The films were produced on Si(100) surfaces under the in situ control of MIES, UPS and scanning tunnelling microscopy (STM). For O2, dissociative adsorption takes place initially and then incorporation of oxygen starts at exposures of ∼5 L. Comparison of the MIES and UPS spectra with those published for CoO shows that near‐stoichiometric CoO films can be obtained by co‐deposition of Co and O2. The CO is adsorbed molecularly up to a maximum coverage of ∼0.6 monolayer, with the C‐end pointing towards the surface. The CO2 adsorption is dissociative, resulting in the formation of Co–CO bonds at the surface. The resulting oxygen atoms are mostly incorporated into the Co layer. For all studied molecules the interaction with Co is similar to that with Ni. Copyright © 2005 John Wiley & Sons, Ltd.
Scenario‐based decision making for architectural variability in product families
Authors: America Pierre , Hammer Dieter , Ionita Mugurel T. , Obbink Henk , Rommes Eelco 
Published: May 2005

AbstractIn this article, we present a systematic approach towards decision making for variability in product families in the context of uncertainty. Our approach consists of the following ingredients: A suitable set of architectural views that bridge the gap between customer needs and available technology, a multiview variation modeling technique, the selection of several scenarios of different kinds, and a quantitative analysis of quality aspects for these scenarios. Copyright © 2005 John Wiley & Sons, Ltd.
Experiences with conducting project postmortems: reports versus stories
Authors: Desouza Kevin C. , Dingsøyr Torgeir , Awazu Yukika 
Published: May 2005

AbstractThe most popular unit of work in organizations is a project. Managing knowledge in and about projects is salient for successful project management. In this article, we will discuss how postmortems can be used to capture tacit experiences in projects. Conducting a postmortem, either after a milestone or at the end of a project, is salient in order to gauge what has been learnt, what were the main issues faced, and what can be used to improve the processes of work in the future. The conducting of postmortems aids in articulation of tacit experiences into explicit forms. This enables for experiences to be better re‐used in the future. Re‐using of postmortem findings depends heavily on the nature of the postmortem outcome. We will compare two kinds of postmortem outcomes—traditional reports and stories. Both types have their pros and cons, and management must choose the right kind of postmortem report to calibrate, depending on the project and learning outcomes. The article will also highlight lessons learnt from conducting postmortem reviews in several software organizations. Copyright © 2005 John Wiley & Sons, Ltd.
Über Organo‐Phosphore mit anorganischem Grundmaterial. II. (Sauerstoffempfindliche Borsäure–Phosphore)
Authors: Chomse Heinz 
Published: May 2005

Abstract1. Borsäure‐Phosphore, die in ihrer Lumineszenzfähigkeit durch die Anwesenheit von Sauerstoff beeinflußt werden, waren bisher nicht bekannt. Es wird die Darstellung von solchen Borsäure‐Phosphoren beschrieben, die in ihrem Verhalten gegenüber Sauerstoff den von H. KAUTSKY gefundenen phosphoreszenzfähigen Farbstoffadsorbaten weitgehend entsprechen und somit die Vorstellungen über die dem Lumineszenzvermögen zugrundeliegenden Mechanismen auf die Borsäure‐Phosphore zu übertragen gestatten.