bluuebunny/crossref_metadata_2025_split huggingface dataset:
β‐Eliminativer Abbau bei 4‐0‐substituierten Hexopyranosiduronat‐Derivaten
Authors: Kiss J. , Burkhardt F. 
Published: December 2004

AbstractTwo types of endocyclic enol‐acetal forming β‐elimination were investigated on synthetic model compounds. In both types the 4‐O‐methanesulfonyl residue was chosen as leaving group. The a,e‐β‐elimination was proved on 2,3‐benzyl ether protected D‐glucopyranosiduronate derivatives I, and the a, a‐β‐elimination on the analogous substituted D‐galactopyranosiduronates XVII. Using a small excess of KOH in methanol at 25°, a quick elimination of a molecule of methanesulfonic acid was observed, and as reaction product the 4,5‐unsaturated 4‐deoxyhexopyranosiduronate derivative II was obtained. Only an unimportant stereoselectivity was found between the a,e‐ and a,a‐mesylate β‐eliminations.The 4,5‐unsaturated 4‐deoxyhexopyranosiduronates show a strong UV. maximum at 238 nm, and Cotton effects in the ORD. spectra. This stable ring system with an endocyclic enol‐acetal linkage is present in a half‐chair (H) conformation.The structure of the unsaturated deoxyhexopyranosiduronate obtained was established by structure‐ and stereo‐correlation with a 2‐deoxy‐L‐xylose derivative, showing that a ring contraction during the β‐elimination does not occur.
L'isomérie géométrique d'amidines mono‐substituées de l'acide benzothiazole‐carboxylique‐2. Isomères anti à carboxyle normal, isoméres syn à carboxyle énolisé
Authors: Baudet Pierre , Rao Dinesh 
Published: December 2004

AbstractThe condensation of methyl benzothiazole‐2‐iminicarboxylate with α‐amino‐acetic esters gives rise to amidines possessing only one (I) of the two possible tautomeric structures. magnified image Both syn and anti isomers have been characterized of the single tautomer. This is the first demonstration of geometrical isomerism around the imine group in amidines.The carboxylic esters and the free acids of the syn fro exist exclusively as the enol, whereas the anti derivatives prefer the carboxyl structure. The existence of these isomers has been confirmed by their IR., UV., and NMR. spectra as well as by the inversion of their configuration and the formation of cyclic derivatives.
Aminodiacylhydrazin‐Umlaǵerungǵ. 5. Mitteilung. Über die Hydrazoessigsäure
Authors: Gisin B. , Brenner M. 
Published: December 2004

AbstractHydrazoacetic acid (7) and a variety of derivatives by alteration of the hydrazo or the carboxyl groups were synthesized. 7 forms complexes with metalions. Under certain conditions N‐acety‐N′‐glycyl‐hydrazoacetic acid (17) undergoes rearrangement into N‐(N‐acetyl‐glycyl)‐hydrazoacetic acid (18).
Sur l'acylation des méthylfluorènes IV. [1] Benzoylation du méthyl‐4‐fluorène
Authors: Chardonnens Louis , Dousse Roland , Horwath Ernö 
Published: December 2004

AbstractBenzoylation of 4‐methylfluorene according to Friedel‐Crafts in carbon disulfide with aluminium chloride yielded two benzoyl derivatives: 5‐methyl‐2‐benzoyl‐fluorene (II) (major product), and 4‐methyl‐2‐benzoyl‐fluorene (III). By oxidation II and III gave the corresponding 9‐oxo‐derivatives, the structure of the last compounds being proved by an independent way.
Die photochemische Anlagerung von Nitrosaminen an Inden
Authors: Wyss E. G. , Schindler O. 
Published: December 2004

AbstractThe 1‐oximino‐2‐amino‐indane derivatives IV‐a and IV‐b are formed by the photoaddition reaction of N‐nitrosomorpholine and N‐nitrosopiperidine with indene. Reduction with LiAlH4 led to the corresponding amines V‐a and V‐b supposed to have trans‐configuration. Substitution of secondary bases to the chlorine atom in the bis‐nitrosochloride II produced compounds of type III which are isomers of IV. The constitution of II was confirmed by conversion to 2‐amino‐indane (VI).
Contribution à l'étude du système quaternaire K+NH4+CrOSOH2O: II. L'isotherme de 25°C
Authors: Flatt R. , Brunisholz G. , Merbach A. 
Published: December 2004

AbstractThe study at 25°C of the system K+NHCrOSOH2O has shown experimentally the existence of a new type of quaternary system of solubility with two cations and two anions. The solubility diagramm is caracterized by the presence of two adjacent ternary limiting systems with a miscibility gap, three univariant lines (one of them being evanescent), one invariant point, three binary and one ternary miscibility gaps.
Über die spektrale Sensibilisierung von Zinkoxid: I. Sorptionsverhalten von o,o′‐Dihydroxyazofarbstoffen
Authors: Brändli R. , Rys P. , Zollinger H. , Oswald H. R. , Schweizer F. 
Published: December 2004

Abstracto,o′‐Dihydroxyazo compounds are spectral sensitizers for the photosemiconductor properties of zinc oxide. It is shown that 1‐(2‐hydroxyphenylazo‐)‐2‐naphthol (II) forms a 1:1 Zn complex on the surface of ZnO particles if adsorbed from toluene solution. With most samples of ZnO a Langmuir type adsorption isotherm is obtained. The concentration of the dye at saturation relative to the BET surface of the ZnO particles correponds to a slightly oblique edge‐on arrangement of the dye molecules on the surfaces.In the case of ZnO pretreated with propionic acid and having taken up dye in excess of a monolayer, it can be shown by electron microscopy that tail‐like complexes (zinc: dye ratio = 1:1) are formed, and that these complexes contain zinc which was originally on the particle surfaces.
Die Cardenolide von Anodendron paniculatum (ROXB.) A. DC. Glykoside und Aglykone, 326. Mitteilung.
Authors: Polonia J. , Jäger Herb. , v. Euw J. , Reichstein T. 
Published: December 2004

AbstractThe wood of Anodendron paniculatum contains a large number of cardenolides; 14 of such compounds could be spottet in PC. and TLC. with Kedde reagent. Five of these (A, E 1, E 2, F, and G) could be isolated in crystalline form and two other ones (B 1 and B 2) as an amorphous mixture. A crystalline aromatic ketone (compound α) was obtained as by‐product. The isolated cardenolides, named as anodendrosides A‐G, were found to be glycosides containing unusual sugars. According to UV. and IR. spectra the genin portion in anodendroside E 1 (probably also in F and B 2) contains a cardenolide structure with saturated ring D and normal butenolide side‐chain, while the anodendrosides A, E 2 and G (probably also B 1) contain an additional double bond at C‐16. The four compounds for which IR. spectra could be taken (A, E 1, E 2, and G) possess a keto group.
Eine Abfangmethode zum Nachweis kurzlebiger Carbenium‐Ionen in stark sauren Reaktionsmedien
Authors: Bosshard H. , Baumann M. E. , Schetty G. 
Published: December 2004

AbstractIn a new approach, unstable carbenium ions produced in strong protic media could be trapped by thioethers yielding sulfonium compounds. The method has successfully been applied to the rearrangement reactions of sec‐butyl alcohol and pinacol, where carbenium ions could be trapped before their rearrangement.In the case of the pinacol‐pinacon rearrangement the carbenium ion 13 has already been discussed but for the first time its existence is proved.Since compound 16 has been found, a new mechanism for the pinacol‐pinacon rearrangement is postulated starting with diprotonated pinacol.
Photoisomerisierung von o‐Di‐isobutenylbenzol
Authors: Ulrich L. , Hansen H.‐J. , Schmid H. 
Published: December 2004

Abstracto‐Di‐isobutenyl‐benzene (4) on irradiation in hexane with a low‐pressure mercury lamp gives 4 photoproducts in an overall yield of 24%. Three of these products were identified as 4, 4, 6, 6‐tetramethyl‐benzobicyclo [3.1.0] hex‐2‐ene (5, main product, 14%), 1.1‐dimethyl‐2‐isopropenyl‐indane (6, 8%) and 1‐isopropenyl‐2, 2‐dimethyl‐indane (10, 2%). 6 is also formed by irradiation of 5 in hexane.
Transformation, par 1′anhydride acètique, d'aldèhydes à caractére èlectrophile prononcè; catalyse par des pyridines. 1. Acyloïnes et hydrates di‐o‐acètylès d'aldèhydes
Authors: Baudet P. , Otten Cl. 
Published: December 2004

Abstract2‐Benzothiazole‐carbaldehyde is transformed into di‐O‐acetyl‐enol‐(benzothiazolecarboxyl‐2)‐oin in the presence of acetic anhydride and of pyridine as catalyst. Without pyridine or with 2,6‐lutidine no reaction occurs. A mechanism of this reaction is proposed. No reaction was observed in the case of benzaldehyde.Choral reacts with acetic anhydride in the presence of pyridine as well as of 2,6‐lutidine as catalyst to give 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane. A mechanism is proposed, in which in an intermediate state the acetate ion (and not pyridine, for steric reasons) attacks the carbon of the carbonyl function of the conjugate acid with the acetylium cation to yield 1,1‐diacetoxy‐2,2,2‐trichloro‐ethane.These two reactions occur only with aldehydes whose carbonyl is very electrophilic, and seem to be a possible way to point out the presence of an acylium cation in pyridine medium.
Über die Stereochemie der Hydrogenolyse von N‐Benzyl‐Bindungen I. Die Hydrogenolyse von Derivaten der 2‐Amino‐2‐phenyl‐propionsäure.
Authors: Dahn H. , Garbarino J. A. , O'Murchu C. 
Published: December 2004

AbstractThe stereochemistry of the hydrogenolysis of benzyl‐N bonds was studied using S(+)‐2‐dimethylamino‐2‐phenyl‐propionic acid (I) and its derivatives, and R(−)‐2‐anilino‐2‐phenyl‐propionic acid (II). The configuration of I was confirmed, that of II established by ORD. measurements, after transformation of the phenyl into cyclohexyl groups. On a palladium catalyst the hydrogenolysis of I, its methyl and ethyl esters and its amide proceeded with 72 to 99% inversion of configuration, that of II with at least 66% inversion. The ester of the quaternary ammonium derivative of I gave as much inversion as retention (= racemisation).
Thermodynamique des mélanges liquides binaires. Chaleurs de mélange des cycloalcanes
Authors: d'Almeida M. Dias , Fernandez‐Garcia J. G. , Boissonnas Ch. G. 
Published: December 2004

AbstractHeats of mixing were measured between 10° and 80°C for all binary systems formed with cycloalcanes CnH2n, n = 5, 6, 7, 8.
Applications of “Artificial Intelligence” for Chemical Inference, VI. Approach to a General Method of Interpreting Low Resolution Mass Spectra with a Computer
Authors: Buchs Armand , Delfino Allan B. , Duffield A. M. , Djerassi Carl , Buchanan B. G. , Feigenbaum E. A. , Lederberg J. 
Published: December 2004

AbstractLe programme connu sous le nom de «Heuristic DENDRAL» est maintenant capable d'interpréter d'une manière absolument automatique les spectres de masse à basse résolution de n'importe quel composé de formule élémentaire CnH2n+vX (X = 0, S ou N, v = valence de X). La possibilité de faire usage de spectres de RMN. pour faciliter l'interprétation a été retenue. Il n'est plus nécessaire de fournir au programme la formule élémentaire du composé dont on veut déterminer la structure. Les données théoriques concernant la spectrométrie de masse et la résonance magnétique nucléaire sont créées par le programme lui‐même. A aucun moment le chimiste n'a besoin de fournir d'autres données que le spectre de masse et, s'il le désire, le spectre de RMN. L'efficacité du programme a été mise à l'épreuve avec 210 spectres de masse. La structure correcte apparaît toujours dans la réponse. Les résultats reportés dans les tableaux 2, 3 et 4 montrent que le nombre d'isomères qui sont compatibles avec la réponse donnée par le programme représente une trés importante réduction du nombre total d'isomères qui sont a priori des candidats possibles.
Stoffwechselprodukte von Mikroorganismen. 84. Mitteilung [1]. Synthese des 5‐Chlor‐6‐methyl‐salicylsäure‐methyläthers, eines Abbauproduktes des Chlorothricins
Authors: Muntwyler R. , Widmer J. , Keller‐Schierlein W. 
Published: December 2004

Abstract5‐Chloro‐6‐methyl‐salicylic acid methyl ether was synthesized starting from 2‐nitro‐5‐hydroxy‐toluene. It was identical with a degradation product of the antibiotic chlorothricin.
Die Alkaloide aus Hedranthera barteri (Hook. f.) Pichon. 139. Mitteilung über Alkaloide
Authors: Agwada V. , Patel M. B. , Hesse M. , Schmid H. 
Published: December 2004

AbstractFrom the root bark of the apocynacea Hedranthera barteri (Hook. f.) Pichon were isolated the known indole alkaloids vobtusine (1), voacamine (2), callichiline (3), voacangine (4) and conoflorine (5), as well as the unknown plant bases amataine, goziline and owerreine, and also beninine and 1, 2‐dehydrobeninine. The structures of the two last mentioned alkaloids were shown in an earlier publication to be 6 and 7, respectively. Amataine, goziline and owerreine are bis‐indole alkaloids, which on the basis of their chemical and spectroscopic (especially mass spectroscopic) properties have been assigned the structures 8, 9 and 10, respectively.
Die Struktur von Panepoxydon und verwandten Pilzmetaboliten
Authors: Kis Z. , Closse A. , Sigg H. P. , Hruban L. , Snatzke G. 
Published: December 2004

AbstractThe structure of panepoxydone (1) and some related products, produced by two species of Panus (basidiomycetes), are proposed on the basis of chemical transformations and physical measurements.The absolute configurations of the main products are deduced by the interpretation of CD. studies and compared with those of the structurally related compounds epoxydone (10), terreic acid (11) and terremutin (12).
Über die 1,2‐Verschiebung von Carbonestergruppen bei der Benzilsäureumlagerung von α,β‐Dioxobuttersäure‐estern. 25. Mitteilung über Reduktone und Tricarbonylverbindungen [1]
Authors: Dahn H. , Gowal Heike , Schlunke H.‐P. 
Published: December 2004

AbstractIn the benzilic acid type rearrangement of t‐butyl α,β‐dioxobutyrate (VII) the intact t‐butoxycarbonyl group is shifted to the β‐carbonyl carbon atom.
O‐Protonation of α‐Diazoketones in Super‐strong Acids
Authors: Wentrup C. , Dahn H. 
Published: December 2004

AbstractPrimary diazoketones, RCOCHN2, are O‐protonated in HFSbF5SO2 or FSO3HSbF5SO2 at −60°, as observed by NMR. The OH‐proton resonates at 9.3–9.6 δ and is coupled with HC 1 (J = 1–2.5 Hz). Secondary diazoketones, RCOC(N2)R, when protonated, give an OH‐singlet at 8.85 δ. The assignments are corroborated by use of deuterated diazoketones, RCOCDN2, or deuterated acid, FSO3D. Primary diazoketones react with FSO3H at −60° to −15°, giving products assigned the fluorosulfate structure, RCOCH2OSO2F; they do not exchange HC 1 with solvent before or during decomposition. Intermediate C‐protonated diazonium ions and α‐oxo‐carbonium ions (vinyl carbonium ions) have not been identified. 3‐Diazo‐4‐methyl‐2‐pentanone (VIII) reacts with FSO3H at −15°, eliminating N2 and giving protonated mesityl oxide by a strictly intramolecular hydride shift.
Eine Synthese O,O‐di‐ und N‐mono‐acylierter L‐Cyclodopaderivate
Authors: Wölcke U. , Kaiser A. , Koch W. , Scheer M. 
Published: December 2004

AbstractAm Beispiel der Synthese von O,O‐Diacetyl‐L‐cyclodopa‐methylester (12) wird eine allgemein anwendbare Methode zur selektiven Acylierung der phenolischen Hydroxylgruppen oder des Indolin‐Stickstoffs am Cyclodopa (8) beschrieben. Die Verwendung von L‐DOPA (5) als Ausgangsmaterial für die Cyclisierung erlaubt die Darstellung grösserer Mengen solcher Derivate.
Modelle für Kopplungsmechanismus und Träger‐induzierten Alkaliionentransport in Mitochondrienmembranen
Authors: Wipf H.‐K. , Simon W. 
Published: December 2004

AbstractEnergetic coupling of oxidative phosphorylation in mitochondria is discussed in the light of recent findings concerning mediation of alkali cation transport by antibiotics: Decoupling by cation‐specific antibiotics of the valinomycin group, as well as by classical decoupling agents (e.g. 2,4‐dinitrophenol), can easily be interpreted on the basis of their known molecular properties if Mitchell's chemi‐osmotic theory is accepted. «Ion pump» mechanisms, as proposed by several authors, require additional assumptions that do not seem justified.
Die Kristallstruktur von 2,4‐Diamino‐5‐(3,4,5‐trimethoxybenzyl)‐pyrimidin‐1‐oxid‐dihydrat. (Ein Metabolit von Trimethoprim)
Authors: Oberhänsli W. E. 
Published: December 2004

AbstractThe crystal structure of the title compound has been determined by threedimensional X‐ray diffraction methods. The crystals belong to the space group P1 with cell constants

a = 7.851 Å
b = 10.703 Å
c = 10.399 Å

α = 100.06°
β = 97.38°
γ = 75.77°

The structure has been refined to an R‐value of 4.0%.The geometry of the molecule and the hydrogen bonding in the crystal are discussed.
Synthèse d'analogues partiellement saturés des neuroleptiques tricycliques clothiapine et octoclothépine. 3me Communication sur les antidépresseurs et les neuroleptiques tricycliques [1]
Authors: Dostert P. , Kyburz E. 
Published: December 2004

AbstractIn order to check if the pharmacological activity is retained when the non‐substituted aromatic ring of the neuroleptics clothiapine (I) and octoclothepine (II) is saturated, we have prepared the trans‐hexahydro‐clothiapine XXIV and one of the two possible diastereoisomers each of cis and trans hexahydro‐octoclothepine XL and XLI.
Terpen‐Verbindungen als Arzneimittel, IX. Die vier stereoisomeren Geranylester der Farnesylessigsäure
Authors: Pala G. , Mantegani A. , Bruzzese T. , Sekules G. 
Published: December 2004

AbstractThe preparation and characterization of the four stereoisomeric trans‐geranyl farnesylacetates I–IV are described. Their structure and configuration were identified by mode of formation, elemental analyses, IR. spectra, and particularly by PMR. spectra.
Stabilité des carboxylates de terres rares, II. Bis‐hydroxyméthyl‐2,2‐propionates
Authors: Roulet R. , Vu Duc T. 
Published: December 2004

AbstractThe stability constants of 2, 2‐bis‐hydroxymethyl‐propionates of rare earths have been determined at ionic strength 0,100 (NaClO4) at 25.0°C by a potentiometric method. The ligand forms 1 : 1 and 1 : 2 complexes with all the rare earths and weak 1 : 3 complexes with light rare earths only. In these last complexes, it binds in a unidentate way. The dissociation constant of the acid has also been measured.
Azidiniumsalze. 7. Mitteilung [1]. Synthese von 1‐Äthyl‐2‐azido‐6‐X‐chinolinium‐fluoroboraten
Authors: Balli H. , Schelz D. 
Published: December 2004

Abstract6‐X‐Quinolines (X = CH3, C6H5, CO2C2H5, Cl, Br) are successively transformed into 1‐methyl‐6‐X‐carbostyrils, 2‐chloro‐6‐X‐quinolines and 1‐ethyl‐2‐chloro‐6‐X‐quinolinium‐tetrafluoroborates; the latter are transformed into the title compounds by reaction with sodium azide in methanol. 2‐Chloro‐6‐acetamido‐quinoline is alkylated at two positions: at the nitrogen atom of the heterocyclic ring and obviously at the oxygen atom of the 6‐substituent; with sodium azide in methanol the product of alkylation yields 1‐ethyl‐2‐azido‐6‐amino‐quinolinium‐tetrafluoroborate. 1‐Ethyl‐2‐azido‐6‐nitro‐quinolinium‐tetrafluoroborate is obtained by treating 1‐ethyl‐2‐hydrazino‐6‐nitro‐quinolinium‐chloride with sodium tetrafluoroborate and sodium nitrite in diluted hydrochloric acid.
Azidiniumsalze. 8. Mitteilung [1]. Darstellung und Eigenschaften substituierter Chinolintriaza‐trimethincyanine
Authors: Schelz D. , Balli H. 
Published: December 2004

AbstractThe synthesis of triaza‐trimethin‐cyanine‐tetrafluoroborates from 1‐ethyl‐2‐azido‐6‐X‐quinolinium‐tetrafluoroborates and sodium azide is described. The visible spectra and the properties of the dyes are discussed.
Reduction of 6‐Trichloromethyl‐2‐pyrones with Metal Hydrides and with Zinc
Authors: Dunkelblum E. , Rey M. , Dreiding André S. 
Published: December 2004

AbstractDie vor kurzem beschriebenen 6‐Trichlormethyl‐2‐pyrone wurden mit Zink und mit komplexen Metallhydriden reduziert. 6‐Trichlormethylpyron (15) und drei an C4 verschieden alkylierte Derivate (5, 16 und 17) ergaben mit Zink in Eisessig die entsprechenden 6‐Methyl‐2‐pyrone 18, 1, 19 und 20. Im Falle des 6‐Trichlormethyl‐4‐(4′‐methyl‐pent‐3′‐en‐yl)‐2‐pyrans (17) bildete sich auch 3,8,8‐Trimethyl‐5,6,7,8‐tetrahydro‐isocumarin (21).Die komplexen Metallhydrid‐Reduktionen wurden am Beispiel des 6‐Trichlormethyl‐4‐methyl‐2‐pyron (5) untersucht. Mit Natriumborhydrid in Äthanol entstanden 6‐Dichlormethyl‐4‐methyl‐2‐pyron (6, 14%) und 6,6,6‐Trichlor‐3‐methyl‐hex‐3‐en‐1, 5‐diol (7, 37%). Mit Lithiumaluminiumhydrid in Tetrahydrofuran erhielt man 6‐Chlor‐ (10, 47%) und 6,6‐Dichlor‐3‐methyl‐hexa‐3,5‐dien‐1‐ol (9, 19%). Für diese Hydridreduktionen wird ein Mechanismus vorgeschlagen, welcher mit den Produkten der Lithiumaluminiumdeuterid‐Reduktion nicht in Widerspruch steht.
An Estimate of the Interatomic Distances in Monohaloacetylene Radical Cations from Photoelectron‐spectroscopic Data
Authors: Heilbronner E. , Muszkat K. A. , Schäublin J. 
Published: December 2004

AbstractA convenient method is given for the semiquantitative determination of those changes ΔSi in internal coordinates, which describe the structure of the radical cation M+(Ψ) relative to the neutral molecule M in its electronic ground state. The changes ΔSi correspond to those associated with the relaxation process which follows the ionisation M + hv → M+(Ψ) + e, M+ being in the electronic state Ψ. The method, based on the procedure originally developped by Smith & Warsop [3], uses the spacing and relative intensity of the vibrational fine‐structure components of the bands in the photoelectron spectrum of M. From these data are calculated the changes ΔQk in normal coordinates, which are then transformed into the ΔSi by applying the L‐matrix.The changes ΔRCX, ΔRCC and ΔRCH which describe the structure of the radical cations of the four monohaloacetylenes I(X) (X = F, Cl, Br, I) in their 2IIΩ(1) and 2IIΩ(2) states have been determined. It is shown that the results are in agreement with theoretical expectation and that they confirm the band assignement proposed in a previous communication [2].
Crystallographic Studies of Synthetic Corrinoids. III. Structural similarities and differences between A/D‐seco‐corrinoid complexes of divalent nickel, palladium and platinum
Authors: Currie Murdoch , Dunitz J. D. 
Published: December 2004

AbstractX‐ray crystal structure investigations of the isomorphous perchlorate salts of complexes of an A/D‐seco‐corrinoid ligand (I) with divalent nickel, palladium and platinum are reported. The structures determined for the Pd‐ and Pt‐complexes are virtually superposable, that of the Ni‐complex, although similar to the other two, shows significant differences with respect to metal coordination and to the spatial relationship of the A and D rings and their substituents. These similarities and differences are discussed in relation to the photochemical A/D cyclization leading to corrin complexes (II).
Studies on Solubilization. (Part I). Note on the synthesis of some quaternary N‐(ω‐aryloxyalkyl) piperidinium, pyridinium, benzyl‐dimethyl‐ammonium, and trimethyl‐ammonium bromides
Authors: Joshi R. K. , Krasnec L. , Lacko I. 
Published: December 2004

AbstractA series of new N‐(ω‐aryloxyalkyl) piperidinium, pyridinium, benzyl dimethyl ammonium, and trimethyl ammonium bromides is described.
The Interaction of π‐Orbitals in Barrelene
Authors: Haselbach E. , Heilbronner E. , Schröder G. 
Published: December 2004

AbstractThe photoelectron spectrum (PE. spectrum) of barrelene (bicyclo[2.2.2]octatriene, 4) is recorded and the first four bands are correlated with orbitals obtained with the MINDO/2‐SCF procedure. The structural changes accompagnying the ionisation process 4 → 4+ are qualitatively derived from the features of the top‐occupied a′2 (π) MO of 4, which shows complete σ‐π separation. The vibrational pattern of the corresponding PE. band 1. as well as complete energy‐minimisation of the geometries of 4 and 4+ support the conclusion that 4 is a rather strained molecule. The interaction of the three πbonds in 4 are discussed in terms of ‘through‐space’ and ‘through‐bond’ interaction with lower lying σ‐orbitals. It is found that the latter is far from being negligible.