bluuebunny/crossref_metadata_2025 huggingface dataset:
Semiempirische MO‐Berechnungen zur Diels‐Alder‐Reaktion, II. Störungsrechnungen zur Produktverteilung der thermischen Homodimerisierung von Butadien‐(1,3), Isopren und Piperylen
Authors: Rasch G. , Sommer M.
Published: January 2005

Quantenchemische Störungsrechnungen auf MINDO/2‐Basis für die thermische Homodimerisierung von Butadien, Isopren, trans‐ und cis‐Piperylen unter Annahme eines einheitlichen cyclischen Modells für den Übergangszustand ergaben qualitative Übereinstimmung mit dem Experiment für die Verteilung der Cycloadditionsprodukte, die größere Reaktivität der substituentenfreien Doppelbindung und die Substitutionsverhältnisse der Sechsring‐Addukte. Die gefundene Asymmetrie der Bindungsbildung stellt den konzertierten Ablauf der Cycloadditionsreaktionen jedoch nicht in Frage.
Reaktion von γ‐Halogen‐α‐cyancrotonsäurenitrilen mit Aminen
Authors: Gewald K. , Hentschel M.
Published: January 2005

Substituierte γ‐Halogen‐α‐cyancrotonsäurenitrile1reagieren mit primären Aminen sowie mit Ammoniak zu substituierten 2‐Amino‐3‐cyanpyrrolen. Arylamine liefern dabei 1‐Arylpyrrole, während mit Alkylaminen 2‐Alkylaminopyrrole entstehen. Die Pyrrolbildung aus dem γ‐Bromnitril1bund Ammoniak bzw. Hydrazin ist mit einer Umlagerung verbunden. α‐Chlorcyclohexylidenmalonitril1creagiert mit Hydrazin zum substituierten Dihydropyridazin11, aus dem durch thermische Blausäure‐Eliminierung das 3‐Aminopyridazin12entsteht.
Physikochemische Analyse der Hydrolyse von N‐(2‐Cyanäthylen‐)harnstoff
Authors: Von Ardenne M. , Berg H. , Fritzsche H. , Reitnauer P. G. , Tümmler R.
Published: January 2005

Mit Pulspolarographie, Infrarot‐ und NMR‐Spektroskopie sowie Elektronenanlagerungs‐Massenspektrographie wurde die Hydrolyse von N‐(2‐Cyanäthylen‐)harnstoff (BA 1) unter noch relativ milden Bedingungen (pH 5,6 bis 9,0; T = 37°C und 22°C) nachgewiesen. Die Hydrolysegeschwindigkeit nimmt mit steigendem pH‐Wert zu. Bei pH 5,6 erfolgt die Hydrolyse sehr langsam (Halbwertszeit etwa 6 Tage), wobei auch schon Kondensationsprodukte nachweisbar sind. Bei pH 9,0 ist bereits nach 2 Tagen BA 1 unter Ringspaltung weitgehend hydrolysiert, und eine Reihe Kondensationsprodukte sind entstanden. Im mittleren pH‐Bereich von 7,3 bis 8,3 wurde das Auftreten von 2‐Cyanaziridin, aber auch schon Ringspaltung und hydrolytische Folgeprodukte beobachtet. Die Halbwertszeit der BA 1‐Hydrolyse konnte bei pH 7,3, 37°C für eine 0,144 molare Lösung in Phosphatpuffer zu 103 ± 1 h bestimmt werden.
Untersuchungen zur Sensibilisierten Photooxidation von 1,3‐Dithiolthionen‐(2)
Authors: Fanghänel E. , Lutze G.
Published: January 2005

1,3‐Dithiolthione‐(2) 1a—h sind sensibilisiert photooxidierbar. Mit Methylenblau als Sensibilisator wird Singulettsauerstoff als Oxidationsreagenz wahrscheinlich gemacht. Die Oxidationsgeschwindigkeit steigt mit der Fähigkeit der Substituenten in 1, die Elektronendichte im Heterocyclus zu erhöhen. Als Hauptprodukte der Photooxidation des 4,5‐Diphenyl‐1,3‐dithiolthions‐(2) 1a wurden 4,5‐Diphenyl‐1,3‐dithiolon‐(2) 8, Dibenzoylsulfid 9 und Benzil 10 neben Schwefelkohlenstoff, Schwefel und Schwefeldioxid isoliert. Das 1,3‐Dithiolon‐(2) 8 reagiert ebenfalls mit Singulettsauerstoff. Ein Weg für die Bildung der Reaktionsprodukte wird diskutiert.
Pyrazolonderivate. II. [5] Synthese von tautomeriefähigen Enaminen einiger 3‐substituierter 1‐Phenyl‐Δ2‐pyrazolinone‐(5)
Authors: Freyer Wolfgang , Tomaschewski Georg
Published: January 2005

Durch Kondensation von 3‐substituierten 4‐Hydroxymethylen‐1‐phenyl‐Δ2‐pyrazolinonen‐(5) mit primären Aminen wurden eine beträchtliche Anzahl stabiler 4‐Aminomethylen‐Δ2‐pyrazolinone‐(5) in guter Ausbeute erhalten. Die gleichen Reaktionsprodukte entstehen, wenn 4‐N, N‐Dimethylaminomethylen‐Δ2‐pyrazolinone‐(5) einer Umaminierung unterworfen werden. Dagegen sind Azomethine, die sich vom 5‐Methoxy‐3‐methyl‐1‐phenyl‐pyrazol ableiten, instabil. Es bilden sich spontan die 4‐Aminomethylen‐Δ2‐pyrazolinone‐(5).
ESR‐Untersuchungen zur Photolyse von σ‐Methyl‐Kobalt(III)‐Chelaten
Authors: Roewer G. , Shagisultanova G. A. , Wojakin I. W.
Published: January 2005

Die anaerobe Photolyse der Komplexe [CH3CoIII(salen)Y] und [CH3CoIII(salphen)Y] mit sichtbarem Licht in den Lösungsmitteln Chloroform, Isopropanol, Methanol und DMF verläuft unter homolytischer Spaltung der CoC‐Bindung. Die resultierenden low spin Co(II)‐Komplexe sind direkt ESR‐spektroskopisch identifizierbar. Sie reagieren in DMF mit Sauerstoff unter Bildung von Superoxidkomplexen [\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm YCo}^{{\rm III}} \left({{\rm salen}} \right){\rm O}_{\rm 2} }^{\scriptstyle {{\relbar}\kern-3pt {.} }} \right] $\end{document}] bzw. \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm YCo}^{{\rm III}} \left({{\rm salphen}} \right){\rm O}_{\rm 2} }^{\scriptstyle {{\relbar}\kern-3pt {.} }} \right] $\end{document}. Das Methyl‐radikal kann mit tert.‐Nitrosobutan abgefangen werden. Bei der aeroben Photolyse der Methyl‐Co(III)‐Komplexe sind sowohl das Methyl‐ als auch das Methoxyradikal nachweisbar.
Zur Molekülverknüpfung mit Schwefelchloriden. IV. Die Addition von Dichlorsulfan an Allyl‐phenyl‐äther. Anti‐Markovnikov‐Struktur der 1:2‐Addukte
Authors: Mühlstädt M. , Stransky N. , Kleinpeter E. , Meinhold H.
Published: January 2005

Molecule Linkage by Sulfur Chlorides. IV. The Addition Reaction of Dichlorosulfane with Allyl‐phenyl‐ethers. Anti‐Markovnikov‐Structure of the 1:2 ‐ Adducts

Allyl‐phenyl‐ethers react with dichlorosulfane (sulfur dichloride) to anti‐Markovnikov‐adducts. This was demonstrated by the 1H‐n.m.r. spectra and dehydrohalogenation of the isolated bis‐(β‐chloroalkyl)‐thio ethers.
Reaktivität und Toxizität homologer Brom‐ und Dibromalkane
Authors: Fischer Gerhard W. , Riemer Fritz , Grüttner Stephan
Published: January 2005

Reactivity and Toxicity of Homologous Bromo‐ and Dibromoalkanes

The rate constants of the reactions of 4‐(4‐nitrobenzyl)‐pyridine (NBP) with ω,ω′‐dibromoalkanes Br(CH2)nBr (n = 2–4), alkyl bromides CnH2+n1Br (N = 2–4) and allyl bromide in acetophenone were measured and compared with the LD50‐values of these compounds estimated on mice. The tested dibromoalkanes show a contrary graduation of reactivity and acute toxicity.
Untersuchungen über die Autoxidation der isomeren n‐Octene
Authors: Pritzkow W. , Radeglia R. , Schmidt‐Renner W.
Published: January 2005

Studies on the Autoxidation of the Isomeric n‐Octenes

The products of autoxidation of the positionally and sterically isomeric n‐octenes were analyzed by gaschromatography. 22–37% of the gaschromatographically detected compounds were epoxides, 2–9% were products of oxidative cleavage of the CC‐double bond, and 50–70% were allylic oxidation products. Independently of the stereochemistry of the starting olefins mixtures of the corresponding cis‐ and trans‐epoxides were always formed; in the oxidation products of cisoctenes more cis‐epoxides are present than in the oxidation products of trans‐octenes. The composition of the octenol mixtures, obtained by preparative gaschromatographic isolation from the sodium sulphite reduction products of the oxidates, could be determined by 13C‐n.m.r. analysis. All expected positional isomers are formed. The trans‐octenes almost exclusively yield the trans‐octenols; from the cis‐octenes the octenols with the double bond in the original position are formed as mixtures of the corresponding cis‐ and trans‐isomers, but the octenols with shifted double bonds almost exclusively are present in their transforms.

The stereochemical results are discussed on the basis of the lifetime and the conformational or configurational stability of the intermediate radicals.

In connection with the 13C‐n.m.r.‐investigation of the reaction products increments for the shift of 13C‐signals by introduction of hydroperoxy, hydroxy, and carbonyl groups in allylic position of olefins were derived.
Massenspectroskopie von Naturstoffen. XV. Vergleichende Kationen‐Anionen‐Massenspektroskopie von Azidogibberellinen
Authors: Voigt D. , Voigt B. , Adam G. , Franke P.
Published: January 2005

Mass Spectrometry of Natural Products. XV. Comparative Positive‐Negative Ion Mass Spectrometry of Azidogibberellins

The fragmentation behaviour of 1‐azido‐3‐hydroxy‐gibberellin derivatives has been studied by means of positive and negative ion mass spectrometry, high resolution and metastable transitions. The results obtained allow a mass spectrometric distinction to be made between epimers with different stereochemistry of the ring A substituents.
Insect growth regulators. XIII. Juvenoids with Cyclopentene Ring. Synthesis of alkyl ω‐(2,2,3‐trimethyl‐cyclopent‐3‐en‐1‐yl)‐2‐alkenoates and ω‐(2,2,3‐trimethyl‐cyclopent‐3‐en‐1‐yl)alkyl phenyl ethers
Authors: Derdziński K. , Wawrzeńczyk C. , Zabza A.
Published: January 2005

Insektenwachstumsregulatoren. XIII. Juvenoide mit dem Cyclopentenring. Synthese von Alkyl‐ω‐(2,2,3‐Trimethyl‐cyclopent‐3‐en‐1‐yl)‐2‐alkenoaten und ω‐(2,2,3‐Trimethyl‐cyclopent‐3‐en‐1‐yl)alkylphenylethern

Neue Analoga, der Insektenjuvenilhormone mit dem Cyclopentenring wurden aus dem (2,2,3‐Trimethyl‐cyclopent‐3‐en‐ 1‐yl)acetonitril (1) durch eine mehrstufige Synthese erhalten. Die Ether 7 a–c, 8a, b, 15 a–c und 34a, b wurden durch Alkylierung der 4‐substituierten Phenolate mit entsprechenden Tosylaten oder Bromiden synthetisiert. Die Ester 11 a–c, 12a, b, 21 a–c, 23 a–c, 28a, b, 29, 27 und 33 a, b mit unterschiedlicher Kettenlänge wurden durch die WADSWORTH‐EMMONS‐Reaktion der Ketone 11, 12, 19, 26, 27, 32 bzw. des Aldehydes 16 mit entsprechenden Phosphonsäurealkylestern erhalten.
Konfigurative Zuordnung über sterisch definierte Epoxidringe. XI. Glycidonitrile. IV.1. Synthese von 1α‐Methyl‐2α‐aryl‐cyclohexan‐1ß‐carbonsäuren aus 4α‐Aryl‐2‐methyl‐1α‐oxaspiro. octan‐2‐nitrilen
Authors: Fischer F. , Palitzsch P.
Published: January 2005

Determination of Configurations by the Aid of Sterically Corresponding Epoxides. XI. Glycidic Nitriles. IV. Synthesis of 1α‐Methyl‐2α‐aryl‐cyclohexane‐1ß‐carboxylic Acids from 4α‐Aryl‐2‐methyl‐1α‐oxaspiro[2, 5]octane‐2‐nitriles

The opening of an epoxide ring of the C‐2‐isomeric glycidic nitriles 1a–b with anhydrous HCl in dry Et2O yields the corresponding chlorocyanohydrines 2a–b. Treatment of these chlorocyanohydrines with diluted NaOH does not give the expected α‐chloroketones 3a–b, but only the original glycidic nitriles. Dehydrocyanation of the chlorocyanohydrines 2a–b is carried out by column chromatography on silica or neutral Al2O3. Favorskii rearrangement of the resulting α‐chloroketones 3a–b gives the angular methylated carboxylic acid methyl esters 4a–b, which are converted to the acids 5a–b by saponification with NaOH in quantitative yield.

Better reaction conditions for the Favorskii rearrangement of 1‐acetyl‐1‐chloro‐cyclohexanes are described.
Synthesis of Methyl 7‐Bromo‐5‐heptynoate ‐ a building block for the carboxylic side chain of prostaglandins
Authors: Thell Fritz , Henning Mechthild , Schick Hans , Schwarz Sigfrid
Published: January 2005

Methyl 7‐bromo‐5‐heptynoate (11) was synthesized in 8 steps using the alkylation of 1‐(2H‐tetrahydropyran‐2‐yloxy)‐2‐propyne with 1‐bromo‐4‐chloro‐butane as a key reaction step. Furthermore it was shown, that also the unprotected propargyl alcohol (12) can be C‐alkylated with high chemoselectivity using 1‐bromo‐4‐chloro‐butane. In this way the number of necessary reaction steps could be reduced without decrease in the total yield. Attempts failed to use trimethylsilyl 4‐bromo‐butanoate or 4‐bromo‐butyl acetate as alkylating reagent in this synthesis.
Photooxidation von Leukofarbstoffen. XII. Kurzzeitspektroskopische Untersuchungen zur Photooxidation von Bis‐schwefelsäuremonoestern der Leukoformen von Thioindigoverbindungen
Authors: Hinzmann G. , Grummt U.‐W. , Langbein H. , Fassler D.
Published: January 2005

Photooxidation of Leuco Dyes. XII. Time Resolved Investigations on the Photooxidation of Bis‐sulfuric Acid Monoesters of Leucothioindigoid Compounds

The photooxidation of 4, 4′‐dimethyl‐6, 6′‐dichlorothioindigosol (1) was studied by means of laser and conventional flash photolysis. Three transients were detected and assigned to a radical R generated by homolytic splitting of one OS‐bond of the parent compound and to two further radicals which are formed from R by hydrolytic cleavage of the second ester group. The latter two radicals are in a protolytic equilibrium with each other and react, depending on the nature of the solvent by H‐atom abstraction, or by disproportionation forming the leuco‐thioindigoid dye or both dye and leuco dye. A mechanistic scheme is proposed.
Anionic surfactants catalysis in the two‐phase oxidation of toluene derivatives with cerium ammonium nitrate a facile Synthesis of Some Benzaldehydes
Authors: Skarzewski Jacek , Młochowski Jacek
Published: January 2005

The catalytic activity of sodium 1‐dodecanesulfonate, sodium dodecyl sulfate, disodium 2‐dodecyl‐1, 3‐propanediyl disulfate (1) and trisodium 2, 2‐bis(sulfonatemethyl)tetradecylsulfate (2) was tested in the two‐phase oxidation of p‐xylene with cerium ammonium nitrate (CAN). Also various toluene derivatives were oxidized with CAN in the presence of sodium dodecyl sulfate. The observed reaction enhancements are discussed in terms of the micelle‐substrate interaction. The catalytic oxidation of some toluene derivatives (3) with a subsequent thermal rearrangement of the oxidation product offers a simple synthetic route to benzaldehydes 4.
Deactivation behaviour of Photoexcited Aryltropylium Ions. IV. Influence of Ion Pair Formation
Authors: Abraham W. , Dreher B. , Kreysig D. , Sadovskij N. A. , Kuzmin M. G.
Published: January 2005

Aryltropylium salts exhibit an unusually effective self quenching of fluorescence in dependence on their concentration in dichlòromethane. The quenching process is investigated by static and time resolved fluorescence measurements. The observed biexponential fluorescence decay is interpreted by the emissions of ion pairs and free cations. The rate constant of fluorescence quenching by formation ion pair is two orders of magnitude greater than the diffusion constant.
Reversed substituent effect on CO Stretching Vibrations in Maleinimide Derivatives
Authors: Perjéssy Alexander , Augustin Manfred
Published: January 2005

The arithmetic means of wave numbers of symmetric and antisymmetric CO stretching vibrations measured in tetrachloro‐ and trichloromethane of 31 substituted maleinimides were correlated with Taft inductive σ* substituent constants. The series of N‐phenyl and N‐(4‐methylphenyl) derivatives exhibit normal i.e. positive values of slope of vs σ* correlations. In series of substituted N‐methylmaleinimides (and probably also in maleinimides) the negative values of slope of vs σ* correlations indicate a reversed substituent effect on the CO stretching vibration. The mechanism of transmission of substituent effects in maleinimidee system is discussed considering the results of above mentioned observations.
Synthese und Reaktionen von 2‐Arylhydrazono‐N‐phenyl‐succinimiden
Authors: Augustin M. , Jeschke P.
Published: January 2005

Synthesis and Reaction Behaviour of 2‐Arylhydrazono‐N‐phenyl‐succinimides

2‐Arylhydrazono‐N‐phenyl‐succinimides 4a–f are prepared by the heating of 2‐ethoxycarbonyl‐3‐hydroxy‐N‐phenyl‐maleimid 1 with arylhydrazines or ammonium salts 2a–c in acetic acid. The Knoevenagel condensation of the methyleneactive compound 4a with aldehydes in the presence of pyridine forms the corresponding Z‐isomers 5a–e.

The succinimides 4a–c are deprotonated to the anions 6a–c, which with heterocumulenes give the new keten‐S,S‐ and keten‐S,N‐acetals 7a–c, 8a–c and (Z/E)‐9a, b. The intramolecular cyclization of 7b and (Z/E)‐9b leads to 1,5‐disubstituted pyrazol‐3,4‐dicarboxylic imides 10a, b. Further derivatives of these heterocyclic series are available by a base promoted opening of the imid ring.
Synthesis of Phosphino Alkane Sulfonates and their corresponding sulfonic acids by reaction of alkalimetal‐phosphides with sultones
Authors: Paetzold Eckhardt , Kinting Annegret , Oehme Günther
Published: January 2005

Alkalimetal salts of dialkyl‐ and diphenylphosphino alkane sulfonic acids (1–4, 6, 7) were prepared by reaction of alkalimetalphosphides with sultones at ambient temperature. The sulfonates can be converted into the free sulfonic acids by ion exchange. This method opens an access to water soluble phosphines (8, 9) which can be important as ligands in transition metal complexes for catalytic processes.

The use of water soluble tertiary phosphines as ligands in catalytic active transition metal complexes seems to be an achievement of the last ten or twelve years [1]. An important aspect of application is the realization of two phase systems with the catalyst in the water phase acting in the interface. After the catalytic process the catalyst can be separated easily from the product and the recovery of the expensive transition metal is possible.

Hydrophilicity of phosphines usually is achieved introducing highly polar hydroxy‐, amino‐, carboxylato‐, ammonium‐, sulfonato‐, and polyether‐groups, respectively, but only tetraalkylammonium‐, polyether‐ and sulfonato‐groups are suitable for a large pH‐range.

Sulfonato groups can be introduced into phenylphosphines by sulfonation with sulfur trioxide in sulfuric acid leading to meta sulfonated products. Especially mono‐ and polysulfonation of triphenylphosphine was investigated by AHRLAND, CHATT et al. [2]. Monosulfonation occurs under mild conditions, but the selectivity of a multiple sulfonation is low, and there are some problems with the separation of reaction products [3]. Nevertheless, phenylphosphines with chiral substituents were sulfonated by this method and used as ligands in rhodium complexes for asymmetric syntheses [4]. A way to a triphenylphosphine sulfonated in the para position was given by SCHINDLBAUER [5], but his method seems to be less satisfactory with respect to yield and selectivity.
Studies on alkylheterocycles. I. A convenient Synthesis of Phthalazines
Authors: El‐Bannany A. A. , El‐Assar A. A. , El‐Nagdy M. H.
Published: January 2005

Ethyl‐2‐arylhydrazono‐2,3‐dioxobutyrate 1a, b reacted with ethylcyanoacetate to yield the pyridazino derivatives 2a, b. Similarly, the pyridazine 2c was obtained via reaction of 3‐arylhydrazonopentan‐2,3,4‐trione with the same reagent. The phthalazines 6 were obtained upon reaction of 2a–c with ylidenemalonitrile 3a, b. The styrene derivatives 7a–d were isolated from the reaction of 2a–c with the appropriate aromatic aldehyde. Compounds 7a–d were subsequently utilized for the synthesis of 6a, d–f respectively via reaction with malononitrile. On the other hand, the phthalazine derivative 8 was formed upon reaction of 2a with either ethylcyanoacetate or malononitrile.
An improved and efficient Synthesis of Quinoxalinecarboxamide 1,4‐Dioxides from benzofuroxan and acetoacetamides in the presence of calcium salts
Authors: Stumm G. , Niclas H.‐J.
Published: January 2005

An improved and efficient method for the preparation of the title compounds 3 is described. Thus, quinoxalinecarboxamide 1,4‐dioxides 3 are synthesized in high yields by reaction of benzofuroxan 1 with acetoacetamides 2 in the presence of catalytic amounts of calcium salts and ethanolamine. The reaction is assumed to involve a chelate mechanism with 4 as intermediate. Side reactions are studied by means of HPLC and TLC.
A novel method for the Amination of 4,6‐Dinitrobenzofuroxan via meisenheimer complexes
Authors: Göuhrmann B. , Niclas H.‐J.
Published: January 2005

The reaction of 4,6‐dinitrobenzofuroxan 1 with alkali metal salts of succinimide, phthalimide, and formamides affords σ‐N–C bonded Meisenheimer complexes 3. The adducts 3a–c may be directly oxidized to the in 7‐position aminated dinitrobenzofuroxan derivatives 6a–c by treatment with aqueous nitric acid. In the case of 6a the oxidation of 3a proceeds with loss of carbon monoxide. For the preparation of 6d–g the alkali metal salts 3d–g must be transformed to the corresponding silver salts 4d–g before oxidation.
Struktur‐Aktivitäts/Selektivitäts‐Beziehungen von Oxidationskatalysatoren
Authors: Kripylo Peter , Koppe Jürgen
Published: January 2005

Structure‐Activity/Selectivity Correlation of Oxidation Catalysts

Various reactive forms of oxygen are active in the selective oxygen functionalization of olefins and aromatic compounds.

These forms are different on different crystal faces of transition metal oxides as shown by their different cation‐oxygen bond lengths. Therefore, face specifity of transition metal oxides as catalysts can be expected for the selective oxidation of hydrocarbons.

Furthermore, the reactivity of the framework oxygen in the transition metal oxides for selective oxygen functionalization of hydrocarbons is dependent on the nature of the catalytic cycle (one‐ or two‐electron‐processes).

Therefore, structure sensitivity of oxidation catalysts on the selectivity of transition metal oxides as oxidation catalysts is possible. Starting from this concept the following phenomena of the activity/selectivity relations are discussed for the most important industrial oxidation catalysts:

—ensemble effects on the selectivity of supported Ag catalysts for the oxidation of ethylene to ethylenoxide.

—face specifity of multicomponent Bi/Mo‐oxide catalysts in the selective oxidation of propylene to acrolein and in the ammoxidation of propylene.

—structure sensitivity of V2O5‐containing catalysts in the oxidation of aromatic compounds.
Study on the Reactions of 3‐Benzoyl‐2,4,5‐pyrrolidinetrione with aliphatic diamines, phenylhydrazine, semicarbazide and guanidine derivatives
Authors: Żankowska‐Jasińska Wanda , Ostrowska Katarzyna
Published: January 2005

3‐Benzoyl‐2,4,5‐pyrrolidinetrione (1a,b) with aliphatic diamines, phenylhydrazine, semicarbazide, and guanidine derivatives yields mono and binary salts (4, 7, 10, 11‐14), enamines (2, 3), imine (5), pyrrolo[3,4‐c]pyrazole (6) and pyrrolo [3,4‐e][1,4]diazepine (8), respectively. The influence of the reagents basicity on the route of cyclocondensation is studied.
Synthesis and characterization of substituted 2‐diazo‐1 ‐oxo‐1,2‐dihydzonaphthalenes and their products of photolysis and thermolysis
Authors: Baumbach B. , Bendig J. , Nagel T. , Lubsky B.
Published: January 2005

Several 2‐diazo‐1‐oxo‐1,2‐dihydronaphthalene{ (1, 2) have been synthesized by reaction of selected hydroxy compounds and 2‐diazo‐1‐oxo‐1,2‐dihydzonaphthalene‐5‐ and ‐4‐sulfonylchloride, respectively.

Photolysis as well as thermolysis of 1 and 2 leads to final products, the nature of which depends on the position of substitution. So, reactions of 5‐substituted derivatives (1) yield the corresponding indene‐3‐carboxylic acids 3 and their esters 5, respectively. In contrast, reactions of 4‐substituted derivatives (2) lead to the formation of the 1‐sulfo‐indene‐3‐carboxylic acid derivatives 4 and 6. Prepared compounds have been characterized by means of mass, ultraviolet, infrared, 1H‐n.m.r. ind 13C‐n.m.r. {pectroscopy.
Pyryliumverbindungen. 46. 4‐Aroyl‐fluoren‐9‐one durch Ringtransformation von 2,4,6‐Triaryl‐pyryliumsalzen mit Indan‐1,3‐dion
Authors: Zimmermann T. , Fischer G. W. , Olk B.
Published: January 2005

Pyrylium Compounds. 46. 4‐Aroyl‐fluoren‐9‐ones by Ring Transformation of 2,4,6‐Triarylpyrylium Salts with Indan‐1,3‐dione

The ring transformation of 2,4,6‐triarylpyrylium salts 1 with indan‐1,3‐dione in the presence of a condensing agent such as piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate leads to 4‐aroyl‐1,3‐diaryl‐fluoren‐9‐ones 6. As reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile, dimethylformamide) or chlorinated hydrocarbons (methylene chloride, chloroform) can be used. The structure of the novel compounds 6 was confirmed by spectroscopic methods as well as by independent synthesis of the fluorenone 6a.
Dielectric Relaxation and Short Range Order of a Liquid Crystalline Benzoate
Authors: Kresse H. , Haas S. , Heinemann S. , Kremer F.
Published: January 2005

Dielectric investigations on 4‐nitrobenzyl 2,5‐bis‐(4‐n‐hexyloxybenzoyloxy)‐benzoate A (10Hz – 100MHz) and a mixture of A and rodlike benzoates B (10Hz – 100kHz) reveal for A two main relaxation mechanisms in the liquid crystalline phases. The low frequency one connected with the reorientation around the short molecular axis shows in mixtures an anormal increase of the intensity with temperature. The unexpected behaviour of the static dielectric constants of A as well as the systematic change of the dielectric data in the mixture with B are interpreted by a systematic change of the antiparallel correlation of A in the short range.
Konformationsanalyse freier und komplexierter Kronenether in Lösung
Authors: Kleinpeter E.
Published: January 2005

Conformational Analysis of Free and Complexed Crown Ethers in Solution

The conformational analysis of the crown ether family by means of n.m.r. spectroscopy is reviewed here. Conclusions about preferred conformations are drawn from dipolar (NOE) and scalar couplings (nJH,H),13C chemical shifts and their temperature dependences as well. Information about the flexibility are available from dynamic n.m.r. spectroscopy and the spin‐lattice relaxation times T1 Also conformational variations as result of the complexation of cations or other guest molecules, flexibility variations and the stoichiometry of the complexes obtained can be readily studied by the same n.m.r.‐parameters. Special remarks are referenced to the respective possibilities of CP‐MAS‐13C‐ n.m.r. spectroscopy in the solid state as well as other alternative methods of conformational analysis in solution as are dipole moment measurements and the RAMAN vibrational spectroscopy. The conformational peculiarities of the crown ether family are summarized.
Energies of optical excitations and ionization potentials for hydrocarbons with multiple bonds according to results of the DVM‐Xα calculations
Authors: Gutsev G. L. , Boldyrev A. I. , Ovchinnikov A. A.
Published: January 2005

The electronic structure of the C2H2, C2H4, and trans‐C4H6 molecules is calculated using the discrete variational Xα‐method (DVM‐Xα). The calculated energies of optical excitations and ionization potentials are compared with both experimental data and results of other nonempirical methods. We conclude that DVM‐Xα is a reliable method for investigating the electronic structure of polyenes.
The electronic structure of all‐trans‐polyenes C2nH2n+2, n = 3–7
Authors: Gutsev G. L. , Boldyrev A. I. , Ovchinnikov A. A.
Published: January 2005

The electronic structure of the C2nH2n+2 trans‐polyenes, n = 3–7, is calculated by the Discrete Variational Xα method (DVM‐Xα). The valence ionization potentials (IP) calculated using the Clementi double zeta basis agree with the known experimental data within several tenths an electron volt. However, the DVM energies of the π → π* optical excitations are systematically underestimated by 0.8–1.0 eV. For polyenes with equal C—C bond lengths, the computed energies of the first optical transitions are smaller than those of polyenes with alternating C—C bond lengths. The charge distribution in polyenes is analyzed in the framework of a Mulliken scheme. The composition of the frontier molecular orbitals (MO) is analyzed.
Discrete spatial symmetries in energy derivatives
Authors: Banerjee Ajit , Jensen James O.
Published: January 2005

Based upon the invariance of N‐particle systems under discrete operations of reflection, inversion, and rotation by 2π/n, a method for obtaining complete sets of relations among energy derivatives of all orders has been presented. The method is based on the criterion that, for a discrete symmetry operation such as reflection across a plane; the change in energy due to simultaneous arbitrary displacements of each particle is equal to another set of “conjugate” displacements of all particles. Applications of the above relations for particular molecular systems possessing a combination of symmetry operations is also presented. Here, via the row echelon analysis, the number of independent derivatives are found, and simple symmetry relations that allow determination of the remaining derivatives are presented. For example, for a homonuclear diatomic molecule with D2h symmetry only 1 of the 6 first derivatives and 1 of the 21 second derivatives need to be independently calculated.
The formation of highly excited H in the reaction H2+(v) + H2 → H + H
Authors: Schatz George C. , Badenhoop Jay K. , Eaker Charles W.
Published: January 2005

A quasiclassical trajectory surface hopping method has been used to study H(v) + H2 → H + H for v = 0, 3, 7, 10, 13, and 17 with an emphasis on determining the H internal energy and angular momentum distributions for high v. For v = 13 and 17, significant cross sections are found for producing H at energies above its dissociation energy. An average metastable H lifetime of 11.5 ps for v = 13 and 4.7 ps for v = 17 is found, but there is also a much longer lived component to the lifetime distributions that is more important for v = 13 than for v = 17. Some of the longer lived metastables correspond to high angular momentum orbiting states of H, but other sources of metastability are also present.
Reactive scattering in hyperspherical coordinates
Authors: Linderberg Jan , Vessal Behnam
Published: January 2005

Preliminary results are presented for transition probabilities in the H + H2 system derived from an adiabatic representation in terms of surface functions on hyperspheres. Special attention is given to the resonance structure for transition probabilities in the first vibrational level.
Symmetry effects in the electronic spectrum of ammonia at low temperature
Authors: Engelking P. C. , Vaida V.
Published: January 2005

A band intensity alternation has been observed in the absorption spectra to the Ã 1A state of NH3 and ND3 cooled in supersonic expansions. The nuclear statistical explanation for this interesting effect is given here.
Matrix elements for the Morse potential using ladder operators
Authors: Berrondo M. , Palma A. , López‐Bonilla J.L.
Published: January 2005

The algebra of the two‐dimensional harmonic oscillator is exploited to obtain matrix elements between eigenstates of the Morse potential. This follows after mapping the latter into the radial equation of the former problem by means of a change of variable and the use of the angular variable as a dummy variable.
Exact wave functions for few‐particle systems: The choice of expansion for coulomb potentials
Authors: McIsaac K. , Maslen E. N.
Published: January 2005

For exact few‐particle wave functions the choice of expansion has a strong influence on the ease with which the coefficients may be determined. Some expansions, such as those involving hyperspherical coordinates, require complicated expressions for Coulomb interaction potentials. The choice of expansion provides a possible means for minimizing algebraic problems in determining the exact wave function. The complexity due to the nonseparable terms in the potential occurs at different stages of the solution of the Schrödinger equation when the expansion is transformed. When solving recurrence relations to determine the wave function, it is necessary to understand the relationship between degrees of freedom in the solution and the boundary conditions. The degrees of freedom in the solution must be chosen to ensure that the wave function is continuous and normalizable and that the derivatives are bounded everywhere.
Analysis of inter‐ring coupling effects in N‐heterobicyclic π‐systems using a structural definition of aromaticity
Authors: Gready Jill E.
Published: January 2005

A purely structural definition of aromaticity based on the average ring bond length and ‐bond order is proposed. The definition is illustrated for N‐heterocycles by reference to theoretical STO‐3G and 3‐21G geometries and charges for some pteridine derivatives. The treatment focuses on the gross structural changes (i.e., ring size, overall degree of π‐electron delocalization, and net ring charges), accompanying chemical changes, such as substitution, tautomerization, ring reduction, and deazination, as well as the structural interdependence of the two rings in a bicyclic ring system.
Hole localization and broken symmetry: A theoretical study of core electron ionization in the Li2 molecule
Authors: Bacskay George B. , Bryant Glenn , Hush Noel S.
Published: January 2005

Ab initio SCF, CI, CEPA, and MCSCF techniques are compared and contrasted in a theoretical study of the 1s core ionized Li2 molecule from the point of view of core hole localization. In agreement with earlier studies of symmetric core ionized molecules, SCF theory is found to give a physically reasonable description of core ionization only when symmetry breaking is allowed. This results in a dramatic lowering of the energy of the core ionized state and hence of the ionization potential. By extension, CI wave functions that are developed in terms of a broken symmetry SCF reference plus its single and double excitations are found to perform significantly better than those constructed from symmetry adapted SCF orbitals. Alternatively, if the full point group symmetry is to be retained, a multiconfigurational treatment is called for and, in agreement with the conclusions of an analogous study on O2 [H. Ågren, P.S. Bagus, and B.O. Roos, Chem. Phys. Letters 82, 505(1981)], it is found that a modestly sized MCSCF wave function is capable of accounting for the energetic effects of symmetry breaking. Potential energy curves for Li2 and several states of core ionized Li2 have been calculated, allowing predictions of the adiabatic ionization potential and vibrational, satellite, and Auger structures in the photoelectron spectrum of Li2 to be made.
Bases for the irreducible representations of O(3) symmetry adapted to a crystallographic point group
Authors: Gould M. D. , Chandler G. S.
Published: January 2005

We construct bases for the irreducible representations of the rotation group O(3) which are symmetry adapted to a Crystallographic point group. We obtain explicit expressions for the cubic groups, which are valid for arbitrary values of the angular momentum quantum number l. Our method yields an efficient algorithm for both analytical and numerical work. An explicit formula for the multiplicities of an irreducible representation for the cubic groups in an arbitrary angular momentum term l is also derived.
Unitary transformation on the model space. Comparison of Brandow's and Kirtman's versions of quasidegenerate many body perturbation theory
Authors: Svrček Michal , Hubač Ivan
Published: January 2005

In this paper we study the unitary transformations on the model space in quasidegenerate many body perturbation theory (QDMBPT). From this point of view we compare Brandow's and Kirtman's versions of QDMBPT up to the fifth order of perturbation expansion. We show that, starting from Brandow's QDMBPT, we can derive various versions of effective Hamiltonians order by order, of which the Kirtman's version is the simplest one. The operator of unitary transformation we express through the correlation operator.
Some iterative techniques for large CI matrices. I. Excited eigenvalues
Authors: Bendazzoli G. L. , Evangelisti S. , Palmieri P.
Published: January 2005

Iterative methods for computing eigenvalues and eigenvectors of large symmetric matrices are discussed using the language of multidimensional partitioning technique. New variants are proposed and found useful particularly for the computation of highly excited states of CI matrices.
Resonances and microlocal analysis
Authors: Sjöstrand Johannes
Published: January 2005

In this paper we outline briefly how microlocal analysis can be applied to give a general approach to the mathematical theory of resonances in the semiclassical limit. We also describe recent results about the asymptotic behavior of resonances generated by closed trajectories and stationary points in the classical flow.
Shape resonances in electron–molecule scattering. A proposed model in terms of S matrix poles and associated generalized quantum numbers
Authors: Krylstedt Peter , Elander Nils , Brändas Erkki
Published: January 2005

As an extension of the recent atomic work of Krylstedt et al. [1, 2], we propose the synthesis of the static exchange plus polarization model within the multiple scattering Xα formalism and the exterior complex rotation method for the study of shape resonances occurring in molecular collisional systems. The bound state multiple scattering Xα method is reviewed with special attention to the form of the various wave functions for the different molecular regions. In connection with the inclusion of continuum electron exchange into the scattering model, we analyze a possible solution to the problem of asymptotical behavior caused by the local density‐based free electron gas approximation used in this case. We also propose a method to fix the cutoff parameter, inherent in the polarization potential, for symmetry‐related molecular participants in the scattering process, thereby obtaining a possible predictive power for the one‐parameter scattering model.

Titchmarsh–Weyl's theory is used to formally connect the above formulation to scattering theory. The theoretical difficulties in obtaining a unique meromorphic continuation of the S matrix are investigated in connection with the requirements on the actual potential to be exterior dilation analytic. Furthermore, the occurrence of asymptotic quantum numbers is noted and discussed in conjunction with muffin tin‐like approximations and related exterior complex rotated schemes.

It is found that the electron exchange part of the nonstatic one‐body potential exhibits a functional form that is not exterior dilation analytic, albeit the general electron and nuclear many‐body problem involving Coulomb forces are dilation analytic. Although the immediate consequences indicate a rotation angle (θ) dependence on the S matrix continuation, a uniquely defined assignment of the cutoff parameter r0 = r0(θ) makes the present nonstatic model “exterior dilation analytic” in the sense that it mimics the dilation analytic structure of the full many‐body problem at the same time obeying “asymptotic” spherical symmetry via the associated constant of evolution. However, in the static exchange approximation the above difficulties are shown to be circumvented via a certain reformulation, leading to a regular analytic asymptotic form for the interaction potential.
Inclusion of relativistic effects into ZDO methods. I. A quasi‐relativistic CNDO/1
Authors: Boča Roman
Published: January 2005

A version of the CNDO/1 method has been outlined that includes dominant relativistic effects. The method utilizes a nonempirical parametrization based on atomic Dirac–Fock calculations. The goal of this QR‐CNDO/1 method lies in its applicability to molecules consisting of arbitrary atoms (z = 1–118). Applications to molecular geometries and ionization potentials for 50 molecules are presented.
Core projection effects in atomic frozen‐core calculations: A numerical analysis
Authors: Luaña V. , Pueyo L.
Published: January 2005

Frozen‐core calculations on the (He) 2s22p6 – 1S state of the F− ion and the (Ar) 3d44s2 – 5D state of the Cr atom, obtained with differently reduced basis sets and different core‐projection schemes, are presented and compared with the corresponding all‐electron results in order to analyze the behavior of the core projection under these circumstances. Severe truncation of the valence basis set can give frozen‐core results noticeably deviated from the all electron values if the regular projection (projection factors xg = 2.0) is adopted. Much better results are obtained in these cases if a softer projection (xg = 1.0) is used for those core orbitals having high electronic density in regions where the valence basis set has low flexibility. In these circumstances the expectation value of the core projector becomes a nonvanishing correction to the valence energy because the core‐valence orthogonality is incomplete after core projection.
SCF Deformation densities and electrostatic potentials of purines and pyrimidines
Authors: Eisenstein M.
Published: January 2005

4‐31G wave functions have been computed for five purines and pyrimidines. The calculated deformation densities have been partitioned into atomic fragments, which were integrated to yield atomic multipole moments. The transferability of atomic fragments between related molecules was verified by constructing model maps for uracil and guanine from appropriate fragments of cytosine and adenine. Model electrostatic potentials calculated from the moments of model atoms are similar to the corresponding 4‐31G potentials. Comparison of 4‐31G and 4‐31G** deformation densities of cytosine provides simple rules for estimating the effects of polarization functions on the atomic multipole moments of most atom types occurring in the purines and pyrimidines. These rules were applied to the other molecules and yielded reasonable approximations for their molecular dipole moments. Substituting CH3 for H has little effect on the deformation density beyond the substitution center.
A comparative study of the bonding in different halides of iridium
Authors: El‐Issa B. D. , Katrib A. , Ghodsian R. , Salsa' B. A. , Addassi S. H.
Published: January 2005

X‐ray photoelectron spectroscopy and multiple scattering Xα calculations have been applied to a series of iridium halide complexes in order to corroborate the nature of the bondings inherent in this class of compounds. Our results seem to substantiate contentiously that higher oxidation states of iridium favor the formation of covalent bonds. This conclusion is based on the observation that (1) successive bombardment of the iridium species by Ar ions almost definitely leads to a configuration in which iridium is bound to at most one halide ion, and (2) the theoretical charge per ligand ion approaches systematically a value of {1−} in the limit as the formal oxidation state of iridium approaches {1+}. The theoretical results are further arthenticated by the fact that the experimental ionization energy of the Ir(4f) level in the different iridium halide complexes studied is seen to decrease as a result of exposure to Ar ions.
Quantum phenomena in small semiconductor structures and devices
Authors: Berggren K.‐F.
Published: January 2005

The ability to artificially structure new semiconductor materials on an atomic scale, using advanced crystal growth methods such as molecular beam epitaxy and metal organic chemical vapor deposition, has led recently to the observation of new physical phenomena as well as the creation of entirely new classes of devices based on band gap and wave function engineering. In these lectures an elementary introduction is given to the quantum aspects of these new structures.
Dimensionality dependence of total energy of closed shells in a bare Coulomb field for large atomic number
Authors: March N. H. , Cizek J.
Published: January 2005

For Z particles moving independently in an unscreened Coulomb potential energy −Ze2/r, it is known that the total energy E = −(3/2)1/3Z7/3 in nonrelativistic theory as Z→∞. The generalization of this result to d dimensions in the same asymptotice limit is obtained as

which includes the known result above for the three‐dimensional case.
The mechanism of bacteriorhodopsin functioning. II. Ejection and injection of proton
Authors: Krasnogolovets V. V. , Protsenko N. A. , Tomchuk P. M.
Published: January 2005

Transmission of vibrational excitation energy conserved in cis‐conformation of retinal to the outlet proton channel is considered from the perspective of quantum theory. A distribution of vibrational excitations in the channel is found; it allowed to calculate the magnitude of the directed drift proton current. The differences between velocities of proton movement in active and passive channels are considered. A transition of retinal from cis‐ to all ‐trans‐ conformation with the subsequent capture of proton by Schiff base out of the inlet channel is described. The lack of proton in this channel, i.e., in the H‐bonded chain, is eliminated at the expense of the capture of a proton out of the cytoplasmic water enviroment. The correspondence between theoretically established states and spectroscopically identified forms of bacteriorhodopsin (inter‐mediates L, M, N, and O) is proposed.
The Hartree–Fock ground state of atomic two‐electron systems and the Wilson–Silverstone 1s orbital
Authors: Hoor Marten J. Ten
Published: January 2005

For the Hartree–Fock ground state of atomic two‐electron systems, the variational function of Wilson and Silverstone, ϕ(r) = (a + kr)−1 exp(‐kr) / (4π)1/2, can be optimized in two complementary ways. For small values of the atomic number Z, all intergrals have been calculated numerically and optimization can be performed accurately. However, as Z increases, loss of significant figures is increasingly detrimental to the optimization process. For sufficiently large values of Z, the integrals may be replaced by asymptotic expansions in terms of (2a)−. As a result of optimization, the parameters and expectation values can be given as expansions in terms of (32Z)−1/2. Both methods yield good results for Z ≈ 25, so that the whole range of Z can be treated accurately. The results have been compared with those derived from other analytical two‐parameter functions. It is found that ϕ(r) is indeed the outstanding two‐parameter function, at least for small and intermediate values of Z.
Path integral formulation of Roothaan's equations
Authors: Marañón Julio
Published: January 2005

The generating functional Z(N) of the molecular orbital theory of N electrons has been projected into a subspace of atomic orbitals. By application of the saddle‐Point approximataions to the corresponding effective action, a set of equations of motion results. These equations are the classical Roothaan's equations of quantum chemistry.
Fifth‐order constant denominator perturbation therory within a localized bond model: Contributions from single and double excitations
Authors: Cullen J. M.
Published: January 2005

A Fifth‐order constant denominator perturbation treatment of all single and double excitations occuring in the third‐order perturbation wave function is presented for the perturbation configuration interaction using localized orbitals (PCILO) method. Contributions from triple and quadruple excitations which decay back to singles and doubles at third order are automatically included in this theory. This method is computationally very fast, with an execution speed proportional to N3, Where N is the number of orbitals present. A [2,1] Padé approximate involving only singles and doubles contributions through to fifth order is shown to be remarkably accurate.
Conformational preferences of modified nucleic acid bases N6‐(Δ2‐isopentenyl) adenine and 2‐methylthio‐N6‐(Δ2‐isopentenyl) adenine by the quantum chemical PCILO calculations
Authors: Tewari Ravindra
Published: January 2005

Conformational preferences of the hypermodified nucleic acid bases N6‐(Δ2‐isopentenyl) adenine, (i6Ade) and its 2‐methylthio derivative (ms2i6Ade) have been investigated theoretically by the quantum chemical perturbative configuration interaction using localized orbitals (PCILO) method.

The predicted most stable conformation of i6Ade and ms2i6Ade are such that the isopentenyl substituent is oriented away from the imidazole moiety of the adenine ring. The atoms N(6), C(10), and C(11) remain coplanar with the adenine ring for both molecules. However, in contrast to the predicted cis orientation of the C(10)C(11) bond with respect to the C(6)N(6) bond in i6Ade, the trans orientation is favored for ms2i6Ade. The plane of the isopentenyl group is rotated by 120° from that of the purine base in i6Ade, whereas rotation by 60° is favored in ms2i6Ade. The favored orientation of the methylthio group with respect to the C(2)N(3) bond is trans; however, the alternative cis arrangement is also quite probable. The conformational implications of the methylthiolation of the isopentenyladenine are brought out in the context of the considerably large range of accessible (β,γ) and χ orientations. The compatible roles of i6Ade and ms2i6Ade in tRNA are thus understood, besides their distinguishing features.