bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen an Siliciumphosphaten
Authors: Makart H. 
Published: December 2004

AbstractDurch Synthesen mit Kieselgel und H3PO4 bei verschiedenen Temperaturen, bzw. mit Kieselgel und P2O5, wurden Silicophosphorsäure H2Si(PO4)2, eine Verbindung 3 SiO2, 2P2O5 und vier polymorphe Modifikationen von SiO2, P2O5, welche als Formen I‐IV bezeichnet wurden, erhalten.
über Struktur und Aktivität der den H2O2‐Zerfall katalysierenden Cu2+‐Komplexe VII
Authors: Sigel H. 
Published: December 2004

AbstractIt has been stated in a preceding paper [3] that only parts of a ligand coordinated to a metal ion can be oxidized by H2O2 (= peroxidative activity). Considering the reversal of this statement to be true, it is shown by means of the peroxidative activity of the Cu2+‐complexes of ATP, ITP, CTP, UTP, and TTP that in these complexes the heteroaromatic groups contribute to the coordination of Cu2+ ion. By analogy with the Cu2+‐ATP‐complex, where a macrocyclic phosphate‐metal‐adenine chelate is formed [4], and based on his experimental results, the author considers the existence of such a macrocyclic chelate in the copper complexes of ITP, GTP, CTP, UTP, and TTP as established. The coordination sites of the heteroaromatic groups in these complexes are discussed.
Untersuchung reversibler Photoprozesse durch Blitzlichtphotolyse III. Photochromie des 1, 3, 6′,8′‐Tetramethyl‐dehydrodianthrons
Authors: Huber J. R. , Wild U. , Günthard Hs. H. 
Published: December 2004

AbstractThe kinetic decay processes of photochromism of 1,3,6′,8′‐tetramethyl‐dianthrone (TMD) are investigated by means of flash photolysis in the solvents cyclohexane and triacetine, as well as in polymethyl‐methacrylate matrices. It is shown that in solution two distinct photochromic states exist which are both fully populated within 5 μs of exitation. The relative population of the two photochromic states is solvent and viscosity dependent. The green photochromic form can also be produced in polymethylmethacrylate matrices. Quenching experiments indicate that both generation and thermal decay kinetics are not influenced by the presence of molecular oxygen. Contrary to prevailing views, the authors conclude that both photochromic states are not triplet states of TMD but probably conformers of the ground state.
Recherches sur les arǒmes 14ecommunication [1] Sur 1′arǒme de café, II Pyrazines et pyridines
Authors: Goldman I. M. , Seibl J. , Flament I. , Gautschi F. , Winter M. , Willhalm B. , Stoll M. 
Published: December 2004

AbstractPyrazines and pyridines occurring in a coffee concentrate are analyzed by two procedures. 24 compounds have been identified and the presence of some 10 more is revealed. The syntheses, mass and infrared spectral data of reference compounds are given.
Zur kenntnis der ätherischen öle 6. Mitteilung [1] die thermische cyclisation des (−)‐(r)‐Linalools. Die struktur der Plinole und einiger derivate mit Iridan‐Gerüst [2]
Authors: Stirickler H. , Ohloff G. , Sz. Kováts E. 
Published: December 2004

AbstractOn heating linalool, all the four possible diastereomeric plinols are formed by way of an intramolecular Alder “ene”‐synthesis. The knowledge of their absolute configuration, shown to be 2A‐2D, allows a discussion of the stereochemical course of this reaction.
Magnetische Kernresonanz‐Untersuchungen über die Struktur der Komplexe aus Nitroaromaten mit aromatischen aminen 10. Mitteilung über nucleophile aromatische Substitutionsreaktionen [1]
Authors: Caveng P. , Zollinger H. 
Published: December 2004

Abstract1. NMR. and visible spectra of the addition products of N,2,4,6‐tetranitro‐N‐methyl‐aniline, 2,4,6‐trinitrochlorobenzene, and 2,4‐dinitro‐6‐cyano‐chlorobenzene with aromatic amines (1‐naphthylamine, N‐mono‐ and ‐di‐methyl‐1‐naphthylamine, 5‐aminotetralin, N‐methylaniline) demonstrate that electron donator‐acceptor complexes (π‐complexes) are formed.
Beiträge zur Chemie der Si‐N‐Bindung, X [1] Oligo‐[1,3‐diaza‐2.sila‐cyclopentane]
Authors: Fink Walter 
Published: December 2004

AbstractAus Dimethyldichlorsilan und Äthylendiamin werden endständig‐chlorfunktionelle Oligo‐[1,3‐diaza‐2‐sila‐cyclopentane] dargestellt,magnified imagein denen sich das Halogen durch Butyl‐, Phenyl‐, Diäthylamino‐ oder Triorganosiloxy‐Reste ersetzen lässt.
Die Strukturen der mittleren Ringverbindungen. XII. Kristallstruktur der 1,1,5,5‐Tetramethylcyclodecan‐8‐carbonsäure
Authors: Dunitz J. D. , Eser H. 
Published: December 2004

AbstractCrystals of 1,1,5,5‐tetramethylcyclodecane‐8‐carboxylic acid are monoclinic, a = 9.22 Å, b = 14.81 Å, c = 11.58 Å, β = 111° 0′, space group P21/c with 4 molecules in the unit cell. The structure has been solved by direct methods and refined by full‐matrix least‐squares analysis of three‐dimensional intensitiy data. The conformation of the ring differs from the previously observed cyclodecane conformation, but the detailed results are abnormal in a number of ways (extremely short CC bond lengths, wide CCC bond angles, large temperature factors). The possibility is discussed that the crystal structure is disordered.
Der Mechanismus der Hydratation von Magnesiumoxid mit Wasserdampf
Authors: Feitknecht W. , Braun H. 
Published: December 2004

AbstractThe hydration of different forms of magnesium oxide by water vapour was studied at room temperature using gravimetric, X‐ray and electron microscopic methods. It takes place in four steps; formation of a layer of chemi‐ and physisorbed water, transition of magnesium and hydroxide ions in the layer of physisorbed water, nucleation of the hydroxide and growth of the hydroxide crystals.
Die Synthese von Acetylen‐carbonyl‐Verbindungen durch Fragmentierung von α, β‐Epoxy‐ketonen mit p‐Toluolsulfonylhydrazin. Vorläufige Mitteilung
Authors: Schreiber J. , Felix Dorothee , Eschenmoser A. , Winter M. , Gautschi F. , Schulte‐Elte K. H. , Sundt E. , Ohloff G. , Kalovoda J. , Kaufmann H. , Wieland P. , Anner G. 
Published: December 2004

AbstractMore than twenty examples illustrate the recently developed oxidoketone‐alkynone‐fragmentation, whereby α,β‐epoxy‐ketones are cleaved under mild conditions with p‐toluenesulfonyl‐hydrazine to give acetylenic ketones or aldehydes.
Über Pterinchemie 23. Mitteilung [1]. Radikalbildung während der Oxydation von Tetrahydrofolsäure und 5,6,7,8‐Tetrahydropterin
Authors: Bobst A. 
Published: December 2004

AbstractEPR. investigations show the existence of one‐electron oxidation of 5,6,7,8‐tetrahydropterine and tetrahydrofolic acid resulting in unstable cationic radicals of red color which are trapped at liquid nitrogen temperature.
Komplexone XLII. Die Untersuchung der 1:1:‐Komplexe von einigen drei‐und vierwertigen Metall‐Ionen mit Polyaminocarboxylaten mittels Redoxmessungen
Authors: Bottari E. , Anderegg G. 
Published: December 2004

AbstractThe formation of complexes of GaIII, InIII, BiIII, ScIII, ZrIV, and ThIV with polyaminocarboxylate ions was investigated using potentiometric measurements with the redox couples Fe3+/Fe2+ and Tl3+/Tl+. Some data concerning the formation of related hydroxo and hydrogen complexes are reported.
Die Kristallstruktur des l, 6‐8, 13‐Bis‐oxido‐[14]‐annulens
Authors: Ganis Paolo , Dunitz J. D. 
Published: December 2004

AbstractCrystals of 1,6‐8, 13‐bis‐oxido‐[14]‐annulene are monoclinic, a = 9,29, b = 9,74, c = 11,46 Å, β = 90,0°, space group P 21/c, with 4 molecules in the unit cell. The structure has been solved by direct methods and refined by full‐matrix least‐squares analysis of three‐dimensional intensity data. The cis‐configuration of the two oxygen bridges is confirmed, and the observed molecular parameters are in full accord with the aromatic properties of the molecule.
Thermische Umwandlung von Phenyl‐penta‐2,4‐dienyläthern in 4‐[Penta‐2,4‐dienyl]‐phenole als Beispiel für [5,5]‐sigmatropische Umlagerungen. Vorläufige Mitteilung
Authors: Fráter Gy. , Schmid H. 
Published: December 2004

AbstractThe reaction between phenol and trans penta‐2,4‐dienyl chloride gave trans penta‐2,4‐dienyl Phenyl ether (I), whereas with a mixture of sorbyl chloride and 1‐methylpenta‐2,4‐dienyl chloride, pure trans, trans hexa‐2,4‐dienyl phenyl ether (IV) and trans 1‐methylpenta‐2,4‐dienyl phenyl ether (V) were obtained. The ether I gave, on heating in dilute solution at 185°, 4‐(penta‐2,4‐dienyl)‐phenol (III) as the main product, and also some 2‐(2‐vinylallyl)‐phenol (II). The ether IV provided, on heating at 165°, in addition to the ortho CLAISEN rearrangement product VI, mainly a mixture consisting of 94% 4‐(1‐methylpenta‐2,4‐dienyl)‐phenol (VIII) and only 6% 4‐(hexa‐2,4‐dineyl)‐phenol(IX). The latter product (IX) was the only para isomer produced on heating ether V, but in addition 22% of the ortho rearrangement product VII was formed.The migrations I → III, IV → VIII, and V → IX, proceeding through a ten membered transition state, are the first [5,5] sigmatropic rearrangements described.
Komplexe von Enniatinen und anderen Antibiotica mit Alkalimetall‐Ionen
Authors: Wipf H.‐K. , Pioda Lavinia A. R. , Štefanac Z. , Simon W. 
Published: December 2004

AbstractCrystalline 1: 1‐complexes of enniatins with potassium salts are described. Complex formation constants of different antibiotics with sodium and potassium are given.
Der Abbau des Insektizides GS 13005 in der Ratte. Strukturaufklärung der wichtigsten Metabolite [1]
Authors: Esser H. O. , Mücke W. , Alt K. O. 
Published: December 2004

AbstractThe structures of the essential metabolites which are excreted by the rat after oral application of GS 13005 (O,O‐dimethyl‐S‐[(2‐methoxy‐1,3,4‐thiadiazole‐5(4H)‐one‐4‐yl)‐methyl] dithiophosphate) have been elucidated. The product of final oxidation, CO2, was found to be the main metabolite (up to 36% of the dose applied). Among the degradation products excreted in the urine (up to 45% of the dose applied) the two most important were isolated. They are 4‐methylsulfinylmethyl and 4‐methylsulfonylmethyl derivatives respectively of the intact 2‐methoxy‐1,3,4‐thiadiazole‐5‐one heterocycle (metabolites III and II, in amounts of 20–25% and 5–7% of the dose applied, respectively). These metabolites originate by methylation and subsequent oxidation from the mercaptomethyl derivative liberated after hydrolysis of the PS bond of the dithiophosphoric acid ester.
Pulsradiolyse organischer Halogenverbindungen I. Nachweis kurzlebiger Charge‐Transfer Komplexe mit Chloratomen
Authors: Bühler Rolf E. 
Published: December 2004

AbstractIn a solution of benzene in carbon tetrachloride a transient absorption in the visible part of the spectrum could be detected. It appears within less than 0.3 μs after the irradiation by a high‐energy electron pulse, and it can be shown to be due to the charge‐transfer complex between the chlorine atoms as electron acceptors and benzene molecules as electron donors. A variety of aromatic hydrocarbons also yield similar absorption bands in the visible. They show a linear correlation between the absorption energy and the ionisation potential of the aromatic molecules, which is typical for charge‐transfer complexes. A minimum value for the equilibrium constant of complex formation is given. The equilibrium is almost fully shifted to the complex side. An estimated G value for the charge‐transfer complex indicates that the complex is actually part of a main reaction in the radiation‐induced mechanism. The decay of the charge‐transfer complex is mostly pseudo‐first order with a half life of a few microseconds.
Kupferkomplexe von Bisamiden, IV UV.‐Banden binuclearer Koordinationsverbindungen ohne Cu‐Cu‐Bindung
Authors: Zuberbühler A. , Kaden Th. 
Published: December 2004

AbstractCupric copper and N,N′‐Bis‐(2‐dimethylaminoethyl)‐oxamid form in aqueous solution six complexes, three of them being binuclear. Potentiometric and spectrophotometric data were used to obtain stability constants and concentration of each complex, and to calculate their electronic absorption spectra. The binuclear compounds show strong absorption bands in the near UV., in analogy to the quite differently structured dimeric copper acetate. It is proposed that all these bands near to 370 nm are of charge transfer type.
Struktur der makrocyclischen Alkaloide Oncinotin und Iso‐oncinotin. 129. (vorläufige) Mitteilung über Alkaloide
Authors: Badawi M. M. , Guggisberg A. , van den Broek P. , Hesse M. , Schmid H. 
Published: December 2004

AbstractTwo new macrocyclic alkaloids oncinotine (1) and isooncinotine (2) have been isolated from Oncinotis nitida BENTH. 1 can be converted into 2 by an amide exchange reaction. The spermidine residue was present in both bases. The structural elucidation was based mainly on (I) the determination of the functional groups, (II) degradation to compounds 12 and 13 and (III) mass spectrometric investigation of 1 and of the above mentioned degradation products.
SN‐2‐artige massenspektrometrische Fragmentierungen bei substituierten N‐Alkylpiperidinen. 10. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen [1]
Authors: Sailer Kathi , Hesse M. 
Published: December 2004

AbstractAn SN2‐type fragmentation was observed on mass spectrometric analysis of N‐(ω‐X‐alkyl)‐2‐alkylpiperidines (X = NRCOR′, CONH2, COOR, NH2). The molecular ion after loss of the 2 alkyl substituent on the piperidine ring may eject the neutral piperideine on attack of the substituent X on the α‐carbon of the N‐substituted alkyl‐chain. Through this process a cyclic fragment ion is formed. The influence of its ring size and of the substituent X on the stability of this fragment was investigated. The SN2 reaction is favoured in the case of production of five‐ and six‐membered rings.
Etudes stéréochimiques VII Synthèses diéniques en série résinique; action des peroxoacides et des hydrures doubles
Authors: Gastambide Bernard , Langlois Nicole 
Published: December 2004

AbstractThrough a DIELS‐ALDER reaction between citraconic anhydride (1) and methyl resinates, the adducts 2a, b, c were obtained. The epoxide 6, derived from 2a, by acidic methanolysis gave 7 with retention of configuration. The structure of the latter compound was demonstrated by 7 → 8 → 9, the dilactone 9 being characterized by an electronic interaction and an «M coupling». Sodium borohydride reduced 2d and 2a, giving the diols 3d and 3a, respectively the cis‐configuration of which was chemically demonstrated.
Stoffwechselprodukte von Mikroorganismen 74. Mitteilung [1]. Synthese des Ferrichroms. 1. Teil: (S)‐α‐Amino‐δ‐nitr‐ovaleriansäure (δ‐Nitro‐L‐norvalin)
Authors: Maurer B. , Keller‐Schierlein W. 
Published: December 2004

Abstract(S)‐α‐Amino‐δ‐nitropentanoic acid (δ‐nitro‐L‐norvaline), an intermediate of the total synthesis of ferrichrome, was synthesized starting from diethyl oxalate and γ‐butyrolactone.
Sur les carbonates basiques de fer (III): I. Carbonate basique de fer (III) amorphe
Authors: Dvořák V. , Feitknecht W. , Georǵes P. 
Published: December 2004

AbstractThe preparation of a non‐stoichiometric basic carbonate of iron (III) is described. The amounts of carbon dioxide and water can vary in large limits, depending on the way the samples are dried. The ratio of Fe2O3:CO2 in a fresh product is nearly one, but decomposition takes place already at room temperature and ambient humidity. When heated slowly, the carbon dioxide is given of in two clear steps, an intermediate product being formed at about 200°C. The basic iron (III) carbonate decomposes between 400° and 500°C to an α‐Fe2O3 with still a small amount of carbon dioxide. The infrared spectra show that in the freshly prepared products the greater part of the CO ions are linked by two oxygen atoms to two iron atoms, and a smaller part probably only by one oxygen to one iron atom. In the intermediate product, part of the CO2_3 ions are linked by two oxygen atoms to one iron atom, or a hydrogenocarbonate group may be formed. The X‐ray diagrams taken with Mo Kα rays show only two broad lines.
Sur les carbonates basiques de fer (III): II. Préparation, radiocristallographie et spectres IR. du (NH4)2Fe2(OH)4(CO3)2 · H2O
Authors: Dvořák V. , Feitknecht W. 
Published: December 2004

AbstractThe obtention of the crystalline basic carbonate of iron (III) and ammonium, (NH4)2Fe2(OH)4(CO3)2 · H2O, is described and its formula is established by chemical analysis and infrared spectroscopy. The powder X‐ray diagram could be indexed tetragonally leading to a body centred elementary cell with a = 12,04 ± 0,02 Å and c = 6,62 ± 0,01 Å.The infrared spectra show that in the CO groups either one oxygen atom is linked to one iron atom or, rather, two oxygen atoms are linked to two iron atoms. The symmetry of the NH groups is lower than C3v. The OH‐groups are linked by hydrogen bonds of 2,75 Å. Two sorts of OH‐groups can be distinguished, with a radius of approximately 1,34 Å and 1, 48 Å, respectively. The iron atoms are octahedrally coordinated by oxygen atoms, but either the octahedra are deformed or the iron atoms are in part coordinated tetrahedrally.
Muscle regeneration, inflammation, and connective tissue expansion in canine inflammatory myopathy
Authors: Salvadori Claudia , Peters Iain R. , Day Michael J. , Engvall Eva , Shelton G. Diane 
Published: December 2004

AbstractInflammatory myopathies (IMs) are relatively common in dogs, and canine IMs have many similarities to human IMs. The aim of this work was to analyze aspects of the pathogenesis of canine IM with an ultimate goal of establishing canine IM as a model for human IM. Muscle biopsies from 16 dogs with a histological diagnosis of IM were analyzed to determine degree of muscle regeneration, presence of eosinophils, expression of selected cytokines and chemokines, and extent of fibrosis. Regeneration, as shown by staining for developmental myosin heavy chain, was more extensive than evidenced with hematoxylin–eosin staining in most cases of canine IM. Expression of mRNA encoding transforming growth factor‐beta (TGF‐β) and eotaxin 3 was upregulated in all cases evaluated. Eosinophils were abundant in most cases, and the connective tissue was variably expanded, as demonstrated by the distribution of the ubiquitous extracellular matrix proteins collagen VI and fibrillin. The extensive regeneration demonstrates that muscle may survive this adverse environment if inflammation and fibrosis can be stopped or reduced. Muscle Nerve, 2005
A semiempirical SCF–LCAO–MO treatment of some oxygen‐ and nitrogen‐containing heterocyclic molecules
Authors: Sallavanti Robert A. , Fitts Donald D. 
Published: December 2004

AbstractThe π‐electronic properties of furan, oxazole, benzofuran, benzoxazole, anthranil, and dibenzofuran are calculated by the semiempirical self‐consistent‐field molecular orbital method. A single set of parameters is found which satisfactorily reproduces the π → π* electronic transition energies and other π‐electronic properties.
Analytic techniques for the coupled multiconfiguration SCF perturbation theory
Authors: Jaszuński Michal , Sadlej Andrzej J. 
Published: December 2004

AbstractThe perturbation theory based on the paired excitation multiconfiguration self‐consistent field approach of Clementi and Veillard is considered. The coupled first‐order perturbed orbital equations are analysed and an appropriate computational scheme for their solution is discussed. The proposed computational scheme is analogous to the technique employed for the solution of the coupled Hartree–Fock equations in the one‐configuration approximation. However, because of the presence ofnondiagonal Lagrangian multipliers and the use of different one‐electron operators for different orbitals, the present scheme raises some new computational problems. In this context a new technique for the solution of the unperturbed multiconfiguration self‐consistent field equations is proposed. A simple illustration of the superiority of the multiconfiguration perturbation approach with respect to the ordinary coupled Hartree–Fock scheme is given. Also the validity of the variation formulation of the presented scheme and its relation to the finite‐field approach are discussed.
Calculation of intermolecular interactions within the PCILO framework using fixed wave‐functions
Authors: Lochmann R. 
Published: December 2004

AbstractThe PCILO method was used to calculate intermolecular interactions using fixed polarities. In this way our calculations are without any iteration cycle.The investigated supermolecules involve London–van der Waals type, hydrogen bonding type, and charge transfer type interactions, respectively. Both stabilization energies and equilibrium distances are in good agreement with the calculated values using optimized wavefunctions.Also the analysis of the individual contributions to the energy reflects well the mechanism of the intermolecular interactions.
Simplifications in the generation and transformation of two‐electron integrals in molecular calculations
Authors: Beebe Nelson H. F. , Linderberg Jan 
Published: December 2004

AbstractApproximate numerical linear dependence among the columns of the two‐electron integral matrix and the positiveness of the Coulomb operator are exploited in order to reduce the number of integrals that need to be calculated when a numerical accuracy is given by the machine in use or by the choice of the investigator. Numerical results presented indicate that the method leads to an algorithm for carrying out the two‐electron integral four‐index transformation which in practice can be achieved in a small fraction (˜1/5–1/3) of the time required to generate the integrals by one of the fastest available Gaussian integral programs, Almlöf's MOLECULE. This effectively removes one of the major bottlenecks of computational quantum chemistry.
An algebraic approach to bound states of simple one‐electron systems
Authors: Čížek J. , Paldus J. 
Published: December 2004

AbstractA very general realization of the so(2, 1) algebra, which easily follows from the basic commutation relations that are satisfied by any pair of mutually conjugate generalized coordinates and momenta, is constructed. Using special cases of this general realization, and closely following the well known derivation of the eigenvalue spectra of the angular‐momentum operators, based on the so(3) algebra, we derive the energy spectrum for the N‐dimensional isotropic harmonic oscillator, and for both the nonrelativistic and the relativistic N‐dimensional hydrogen atom. Special attention is given to a simple derivation of the form of these Hamiltonians in terms of the so(2, 1) algebra generators. In particular, the usually exploited tilting transformation is avoided, and the whole derivation is presented in an extremely simple and straightforward way. The present approach stresses the similarity and mutual relationship between the systems studied and, in addition to introducing some novel techniques and providing considerable insight into the overall structure of these problems, also has a definite pedagogical value.
Angular dependence of Gaussian‐Lobe orbitals. I. Analysis of standard p‐ and d‐orbitals
Authors: Le Rouzo H. , Silvi B. 
Published: December 2004

AbstractMultipole expansions of Gaussian‐lobe atomic orbitals around their centers are theoretically investigated in order to study the exact angular dependence of such functions. Analytical expressions of the multipole coefficients are derived for standard lobe orbitals. It is shown that the average‐square values of multipole components are related to a unique orbital parameter λ. The numerical values of p‐ and d‐components are given for selected λ and the choice of this parameter is discussed on the basis of symmetry and computational arguments. The transferability of optimized atomic exponents from harmonic (or Cartesian) functions to lobe functions is established so that the possibility of applying the Gaussian‐lobe orbital approach in chemical studies is greatly extended.