bluuebunny/crossref_metadata_2025 huggingface dataset:
Vinylkationen, 38. Synthese und Solvolyse 3‐substituierter 1‐Cyclobutenyl‐nonaflate
Authors: Auchter Gerhard , Hanack Michael
Published: June 2007

3‐Methyl‐ (8a) und 3‐Cyclopropyl‐1‐cyclobutenyl‐nonaflat (8b) sowie 2‐Cyclopropyl‐1‐cyclobutenyl‐nonaflat (12) und das unsubstituierte 1‐Cyclobutenyl‐nonaflat (3) wurden aus den entsprechenden Cyclobutanonen und Nonafluorbutansulfonsäureanhydrid (10) synthetisiert. Die Geschwindigkeitskonstanten und Produktzusammensetzungen der Solvolysen in Trifluorethanol und Trifluorethanol/Wasser‐Gemischen wurden ermittelt. Alle 1‐Cyclobutenyl‐nonaflate solvolysieren nach einem SN1‐Mechanismus über das nichtklassische 1‐Cyclobutenyl‐Kation als Zwischenstufe, das durch die Substituenten in 3‐Stellung zusätzlich stabilisiert wird.
Unterschiedliche [4 + 2]‐Cycloaddukte aus 7,7‐Difluor‐ und 7,7‐Dialkoxy‐1,3,5‐cycloheptatrienen mit 4‐Phenyl‐1,2,4‐triazolin‐3,5‐dion
Authors: Welt Günther , Wolf Elisabeth , Fischer Peter , Föhlisch Baldur
Published: June 2007

4‐Phenyl‐1,2,4‐triazolin‐3,5‐dion (PTAD) bildet mit 7,7‐Difluor‐, 7,7‐Dimethoxy‐, 7,7‐(Trimethylendioxy)‐ und 7,7‐(Ethylendioxy)‐1,3,5‐cycloheptatrien (1c–f) 1:1‐Cycloaddukte unterschiedlicher Struktur. Nach 13C‐ und 1H‐NMR‐Spektren besitzen die Cycloaddukte aus 1d, e und dem unsubstituierten Cycloheptatrien eine Struktur, die sich vom Norcaradien‐Valenztautomeren (2a, d, e) durch [4 + 2]‐Cycloaddition ableiten läßt (NCD‐Typ, 4). Bei 1c, f und beim Tropon dagegen erfolgt [4 + 2]‐Cycloaddition an C‐1/C‐4 des Cycloheptatrien‐Skeletts: es entstehen Addukte vom CHT‐Typ 3.
Synthesis and Reactivity of 2‐Aroylbenzoic Acids, II. 2‐(4‐Hydroxy‐3‐isopropylbenzoyl)benzoic Acid
Authors: Rumiński Jan K. , Przewoska Krystyna D.
Published: June 2007

Synthese und Reaktionsfähigkeit von 2‐Aroylbenzoesäuren, II. 2‐(4‐Hydroxy‐3‐isopropylbenzoyl)benzoesäure

Die Friedel‐Crafts‐Acylierung von 2‐Isopropylphenol mit Phthalsäureanhydrid liefert nur die 2‐(4‐Hydroxy‐3‐isopropylbenzoyl)benzoesäure (1) vom p‐Acylphenol‐Typ. Die Reaktionsfähigkeit der Säure 1 wurde untersucht, und ihre Derivate 2–10 werden beschrieben.
Ab‐initio‐MO‐Studie Methyl‐ und Phenyl‐substituierter Allenyl‐Kationen
Authors: Mayr Herbert , Schneider Reinhard
Published: June 2007

An den Methyl‐ und Phenyl‐substituierten Allenyl‐Kationen 3 – 12 (Tab. 1) wurden ab‐initio‐MO‐Berechnungen unter Verwendung des STO‐3G Basissatzes durchgeführt. Die berechneten Bindungslängen und Ladungsverteilungen zeigen Delokalisierung der positiven Ladung an, wie in Formel 1 gezeigt. Mit Hilfe isodesmischer Reaktionen werden Stabilisierungsenergien von Substituenten in 1‐ und 3‐Position ermittelt. Diese Werte ermöglichen in Kombination mit der experimentell bekannten Bildungswärme des Stammkörpers 2 die Bestimmung von ΔH sämtlicher Allenyl‐Kationen 3 – 12. Der Vergleich dieser Daten mit einigen experimentell bestimmten Bildungswärmen zeigt Übereinstimmung innerhalb von 2 kcal/mol. Es werden Voraussagen für das Reaktionsverhalten gegenüber n‐Nucleophilen und π‐Systemen gemacht.
Additions‐ und Cycloadditionsreaktionen von Allenyl‐Kationen mit acyclischen 1,3‐Dienen
Authors: Mayr Herbert , Klein Herbert
Published: June 2007

Die Zinkchlorid‐Ether‐katalysierte Umsetzung von Propargylchloriden 1 mit acyclischen Dienen 2 liefert bei −78°C die linearen Additionsprodukte 3 bzw. 4, die unter Lewis‐Säure‐Katalyse bei höheren Temperaturen zu den cyclischen Vinylchloriden 5 umlagern. Nur solche Kombinationen aus 1 und 2 liefern dabei 1:1‐Produkte, bei denen die Edukte 1 rascher dissoziieren als die Produkte. Andernfalls entstehen höhermolekulare Verbindungen wie z.B. das 2:1‐Produkt 6. Die Reaktionsmechanismen der Additionsreaktionen werden diskutiert.
Carbonyl‐Monoolefin‐Derivate des Chroms, Molybdäns und Wolframs, III. Darstellung und Reaktivität von Tricarbonyl‐Chelatphosphan‐Olefin‐Komplexen
Authors: Schenk Wolfdieter A. , Müller Helmut
Published: June 2007

Monoolefin‐Komplexe M(CO)3(R2PC2H4PR2)(ol) (M = Cr, Mo, W; R = CH3, C6H5; ol = Maleinsäureanhydrid, Dimethylfumarat, Dimethylmaleat, Methylacrylat, Ethylen, Styrol, Norbornen) sind photochemisch aus den Tetracarbonyl‐Chelatphosphan‐Derivaten zugänglich. Es entstehen zunächst faciale Komplexe, die sich zum Teil rasch intramolekular in die meridionalen Isomeren umlagern. Die Substitution des Olefins verläuft nach einem dissoziativen Mechanismus, der Spaltung der Metall‐Olefin‐Bindung geht bei den meridionalen Derivaten die intramolekulare meridional‐facial‐Isomerisierung voraus.
Kristall‐ und Molekülstruktur von Tetraaryl‐3,7‐diazabicyclo‐ [3.3.1]nonanen und Tetra‐ und Pentaaryl‐1,3‐diaza‐adamantanen. Sessel/Boot‐Konformation der Tetraaryl‐3,7‐diazabicyclo[3.3.1]nonane
Authors: Quast Helmut , Müller Bodo , Peters Eva‐Maria , Peters Karl , von Schnering Hans Georg
Published: June 2007

Für Struktur‐ und NMR‐Untersuchungen wurden die 2,4,6,8‐Tetrakis(3,5‐dimethylphenyl)‐3,7‐diazabicyclo[3.3.1]nonane8cund10c, die davon abgeleiteten 1,3‐Diazaadamantane11cund13csowie an einem (14b,16b) oder an beiden Stickstoffatomen methylierte Tetraaryl‐3,7‐diazabicyclo[3.3.1]nonane (15b,c,17b,c,19) synthetisiert. DieN‐Methylierung erfolgte regioselektiv am Boot‐Piperidinring und erst unter verschärften Bedingungen am Sessel‐Piperidinring.8bbildete mit 4‐Methylbenzaldehyd unter Änderung der Konfiguration eines Benzylkohlenstoffatoms des Sessel‐Piperidinrings langsam das Pentakis(4‐methylphenyl)‐1,3‐diazaadamantanon12b. Durch Röntgenstrukturbestimmung der 3,7‐Diazabicyclononane8c,15bund16bsowie der 1,3‐ Diazaadamantanone12bund20wurden die Strukturen und die im Kristall bevorzugten Konformationen, insbesondere der Arylgruppen, aufgeklärt. Alle Tetraaryl‐3,7‐diazabicyclononane liegen danach in der Sessel‐Boot‐Konformation mit äquatorialen Arylgruppen vor. Zwei der fünf Arylsubstituenten von12bbesetzen eine 1,3‐diaxiale Stellung, während die drei benachbarten Arylgruppen eine unerwartete propellerähnliche Anordnung aufweisen.
Koordinationschemie funktioneller Phosphor‐Ylide, IV. Kristallstruktur von 2‐Methyl‐2‐(triphenylphosphonio)dithio‐propionat und 3,5‐Diisopropyliden‐1,2,4‐trithiolan. Zum Ablauf der Betain‐Trithiolan‐Umlagerung
Authors: Kunze Udo , Merkel Reinhard , Winter Werner
Published: June 2007

Die Additionsprodukte von Phosphor‐Yliden Ph3P = CR1R2(1) und Kohlenstoffdisulfid liegen in Abhängigkeit von den Substituenten R1, R2als Betaine2, Dithiocarbonsäuren3oder Ylid‐Anionen4vor.C,C‐Dialkylsubstituierte Betaine liefern als thermische Folgeprodukte Dialkyliden‐1,2,4‐trithiolane6, die wahrscheinlich durch [3 + 2]‐Cycloaddition des Thioketens5und des Betains2unter PPh3‐Eliminierung entstehen. 2‐Methyl‐2‐(triphenylphosphonio)dithiopropionat (2a) kristallisiert orthorhombisch in der RaumgruppeP212121(Z= 4) mit den Zellparameterna= 8.724(2),b= 13.839(3),c= 15.873(5) Å (Meßtemp. −100° C). Das Molekül liegt in der offenen Betain‐Form mit schwacher elektrostatischer Wechselwirkung zwischen P1 und S1 und signifikant gedehnter P1  C2‐Bindung (1.880 Å) vor. Das Trithiolan6akristallisiert monoklin (RaumgruppeC2/c,Z= 4,a= 12.658(4),b= 6.482(1),c= 12.891(1) Å, ß = 109.01(1)°) und nimmt eine Halbsessel‐Konformation (C2‐Symmetrie) ein.
Nucleophile Addition von Triorganozinn‐Anionen an Kohlenstoffdisulfid, II. Isolierung von Alkali‐triphenylstannandithiocarboxylaten und Aufbau von Metallcarbonyl‐Komplexen
Authors: Kunze Udo , Hättich Thomas
Published: June 2007

Die durch nucleophile Addition von Triphenylstanny‐alkaliverbindungen an Kohlenstoffdisulfid entstehenden Triphenylstannandithiocarboxylate lassen sich als Dioxan‐Addukte1a–cstabilisieren. Ihre Umsetzung mit verschiedenen Carbonyl‐ und (η5‐Cyclopentadienyl)carbonylmetall‐halogeniden führt zu den in Lösung licht‐ und luftempfindlichen, in fester Form aber stabilen, Triphenylstannandithiocarboxylato‐Komplexen2b,3b(Re),3a,4a(Mn),5a,b(Fe),6a(Mo) und6b(W). Neben der chelatartigen Koordination des Liganden gelingt es bei2bund5a, auch die einzähnige Verknüpfung zu realisieren. Die IR‐,1H‐NMR‐,13C‐NMR‐ und UV‐Spektren aller neuen Verbindungen werden diskutiert.
Einführung von Sauerstoff‐Funktionen in die α‐Stellung von β‐Diketonen, 9. Ozonolytische Fragmentierung von Pyridinium‐Yliden
Authors: Schank Kurt , Lick Carlo
Published: June 2007

Introduction of Oxygen Functions into the α‐Position of β‐Diketones, 9. Ozonolytic Fragmentation of Pyridinium Ylides

Pyridinium diacyl methanides 3 are cleaved by equimolar amounts of ozone in aprotic medium yielding vicinal tricarbonyl compounds 6 and pyridine. Peroxidic reaction products are not detectable.
(E)‐3‐(1,3‐Dithian‐2‐yl)acroleine als geschützte Fumardialdehyde durch Oxopropenylierung des 1,3‐Dithians
Authors: Rustemeier Klaus , Breitmaier Eberhard
Published: June 2007

(E)‐3‐(1,3‐Dithian‐2‐yl)acroleins as Protected Fumardialdehydes via Oxopropenylation of 1,3‐Dithiane

Lithiated 1,3‐dithiane 1 undergoes a stereoselective nucleophilic addition to 3‐ethoxyacroleins 2 yielding (E)‐3‐(1,3‐dithian‐2‐yl)acroleins 5. Upon oxidative cleavage with N‐bromosuccinimide, these are convertible to the corresponding fumardialdehydes 6, isolable as 2,4‐dinitrophenyl‐hydrazones 7.
Facile Synthesis of 2‐Alkoxy‐2‐aryloxiranes
Authors: De Kimpe Norbert , De Buyck Laurent , Verhé Roland , Schamp Niceas
Published: June 2007

Tertiary α‐bromoalkyl aryl ketones 1 were converted into 2‐alkoxy‐2‐aryloxiranes 4 exclusively by reaction with excess potassium carbonate in the corresponding dry alcohol. Silver carbonate in a dry alcohol with these α‐bromo ketones yielded competitively formation of 2‐alkoxyoxiranes and semi‐benzilic Favorskii rearrangement (→5), while silver hexafluoroantimonate in the same medium afforded the latter rearrangement reaction exclusively.
Dikation‐ether und verwandte Verbindungen, 1. Über Dikation‐chalkogenide und ‐dichalkogenide
Authors: Maas Gerhard , Singer Berndt
Published: June 2007

N,N‐, N,S‐, S,S‐ und O,O‐substituierte Thione 4a–f und Selone 6a–c reagieren mit Trifluormethansulfonsäureanhydrid zu Dikation‐disulfiden 5a–f bzw. ‐diseleniden 7a–c. Die Bildung von Dikation‐sulfiden (Dikation‐seleniden), welche eine Parallele zum Reaktionsverhalten der analogen Harnstoffderivate darstellen würde, wird nicht beobachtet. Diese Verbindungsklasse (14, 15) ist jedoch durch Reaktion von Dikation‐ethern 13 mit Thionen 4 bzw. Selonen 6 zugänglich. 1H‐ und 13C‐NMR‐Daten der Dikation‐dichalkogenide und ‐chalkogenide werden miteinander verglichen.
Syntheses and molecular Structures of formal Heterocumulenes with and units
Authors: Jochims Johannes C. , Rahman Mohammed Abdur , Zsolnai Laszlo , Herzberger Siegfried , Huttner Gottfried
Published: June 2007

The cyanamides 1 and 3 react with tertiary alkyl chlorides and antimony pentachloride affording formal heterocumulenes SbCl6− (2a, b) and SbCl6− (4a, b). X‐ray analyses of 2b and 4b reveal that in the crystal these compounds are bent pseudocumulenes having structural properties of nitrilium salts (B) and of carbodiimides (D). With amines and alcohols 2 and 4 react to give compounds 11–17 which are probably not amino‐substituted 2‐azaallenium salts E but guanidines F.
CC‐Doppelbindungen mit extremer Reaktivität, III. Versuche mit 9‐(9‐Fluorenyliden)xanthen
Authors: Schönberg Alexander , Singer Erich , Stephan Werner
Published: June 2007

CC Double Bonds with Extreme Reactivity, III. Reactions of 9‐(9‐Fluorenylidene)xanthene

According to equations (1) to (4), 9‐(9‐fluorenylidene)xanthene (2) reacts with sulfur, malonodinitrile, aniline, or thiophenol to give the compounds 3, 5, 7–11, and diphenyl disulfide.
Über die sensibilisierte [2 + 2]‐Photocycloaddition von Dichlorvinylencarbonat an endo‐Bicyclo[2.2.1]hept‐5‐en‐2,3‐dicarbonsäure‐dimethylester
Authors: Ried Walter , Bellinger Oswald , Bats Jan W.
Published: June 2007

Bei der sensibilisierten [2 + 2]‐Photocycloaddition von Dichlorvinylencarbonat (2) an endo‐Bicyclo[2.2.1]hept‐5‐en‐2,3‐dicarbonsäure‐dimethylester (1) wird selektiv nur das Isomerenpaar (3a, b) isoliert, in dem der Vierring die exo‐Stellung einnimmt. Die genaue Konformation der Dichlorethylencarbonatgruppe von 3b konnte durch Röntgenstrukturanalyse geklärt werden. Hydrolyse des maskierten α‐Diketons 3 in Aceton/Wasser ergibt, im Gegensatz zu ähnlichen Photoaddukten, das Diketon 4 sowie als Nebenprodukt das Acetonaddukt 5.
Elektron‐Donor‐Acceptor‐Verbindungen, XXXIII. Intramolekulare Chinhydrone der [3.3]Paracyclophan‐Reihe
Authors: Staab Heinz A. , Herz Claus P. , Krieger Claus , Rentea Marina
Published: June 2007

Zur Synthese der [3.3]Paracyclophan‐Chinhydrone 1 und 2 wurden die 2,13‐Dithia[4.4]paracyclophane 5/6 dargestellt, deren Disulfone 7/8 durch Gasphasen‐Pyrolyse die diastereomeren Tetramethoxy[3.3]paracyclophane 9 und 10 ergaben. Aus 9 erhielt man durch Demethylierung und anschließende Oxidation 1, aus 10 entsprechend 2. Die von 1 und 2 abgeleiteten Dimethylether 3 und 4 wurden aus 7/8 dargestellt. Beide Isomerenpaare (1/2 und 3/4) demonstrieren die starke Abhängigkeit der Charge‐Transfer‐Absorption von der Donor‐Acceptor‐Orientierung (Abb. 1). – Die Zuordnung der Verbindungen 1–4 zur pseudoortho‐ bzw. pseudogeminalen Reihe wurde durch Röntgenstrukturanalysen geklärt. Molekül‐ und Kristallstrukturen von 4, 9 und 10 werden diskutiert.
Synthesis of α‐Cyanoenamines by Cyanation of α‐Bromoimmonium Bromides and Dehydrobromination of β‐bromo‐α‐(dialkylamino)nitriles
Authors: De Kimpe Norbert , Verhé Roland , De Buyck Laurent , Schamp Niceas
Published: June 2007

The reaction of α‐bromoimmonium bromides 4 with potassium cyanide in dimethylformamide gave rise to β‐bromo‐α‐(dialkylamino)nitriles 5, which were dehydrobrominated in various basesolvent systems to afford (E)‐ and (Z)‐α‐cyanoenamines 2. An adaption of a previously published preparation of α‐cyanoenamines starting from aldehydes via enamines led to an improved, efficient and fast synthesis of the title compounds.
Substitutionsreaktionen an Galliumhalogeniden mit Silylsulfiden
Authors: Hoffmann Gerhard G.
Published: June 2007

Die Galliumhalogenide GaCl3, GaBr3 und GaI3 (1, 2 und 3) reagieren mit den Silylsulfiden (CH3)3SiSCH3, (CH3)3SiSC2H5 (4, 5 und 6) in Benzol unter Bildung der extrem feuchtigkeitsempfindlichen Mono‐, Bis‐ und Tris(alkyl‐ bzw. phenylthio)gallane 7–22. Spektroskopische Daten sowie einige physikalische und chemische Eigenschaften der neuen Verbindungen werden mitgeteilt. Der mögliche Bildungsmechanismus und ein interessantes strukturelles Phänomen der Diiod(alkylthio)gallane 12, 13 werden diskutiert.
Cycloaddition von Amino‐, Phosphino‐ und Thionitrilen sowie Phosphinoisocyaniden an die Azido‐Liganden planarer Rhodium(I)‐, Iridium(I)‐, Palladium(II)‐ und Platin(II)‐Verbindungen: Tetrazolyl‐Chelatkomplexe
Authors: Erbe Jürgen , Beck Wolfgang
Published: June 2007

Amino‐, Phosphino‐ und Thionitrile werden an die Azidliganden planarer d8‐Verbindungen von PdII, PtII, RhI und IrI unter Bildung von 5‐R‐Tetrazolato‐Komplexen 2–8 addiert. Neuartige Chelat‐Komplexe 9, 10, 12–15, 17 werden mit 2‐Pyridincarbonitril, (2‐Cyanethyl)diphenylphosphan, (2‐Cyanphenyl)diphenylphosphan bzw. (2‐Isocyanethyl)diphenylphosphan erhalten, wobei Cycloaddition und Bindung des Pyridin‐N‐Atoms bzw. der Diphenylphosphinogruppe an das Metall erfolgt.
A Fourier Transform Ion Cyclotron Resonance Study of the Structure of some Phenyl‐substituted 2‐Azaallenium Ions
Authors: Kleingeld Jan C. , Nibbering Nico M. M. , Halim Herman , Schwarz Helmut , Würthwein Ernst‐Ulrich
Published: June 2007

It is shown by proton abstraction reactions in combination with deuterium labelling that the initial structure of the ions 1–3 generated by electron impact from some benzylideneamines through loss of an alkyl radical via α‐cleavage is indeed that of phenyl‐substituted 2‐azaallenium ions. The deprotonated species appear to have very high gas‐phase basicities, that are higher than 231.7 kcal/mol.
Neuartige photochrome Systeme: Tetra‐, Hexa‐ und Octahydroindolizine
Authors: Dürr Heinz , Groß Hubert , Zils Klaus‐Dieter , Hauck Gerd , Klauck Günter , Hermann Horst
Published: June 2007

In dieser Arbeit werden neuartige Spiro‐tetra‐ (5,5′), Spiro‐hexa‐ (6) und Spiro‐octahydroindolizine (7) vorgestellt. Die Synthese von 5,5′, 6a, b und 7 wird beschrieben. Lanthanoidenverschiebungen werden zur Strukturermittlung eingesetzt. UV‐Kinetische – insbesondere blitzspektroskopische – Studien zeigen, daß die reversible elektrocyclische Reaktion der Tetrahydroindolizine 5 für die Photochromie verantwortlich ist. Eine Ausnahme bildet 5′h; 6a, b und 7 sind nicht mehr photochrom.
RC admittance realization by grounded‐capacitor structures
Authors: Stein Richard A.
Published: June 2007

A computer‐aided synthesis method is described for multi‐port RC networks with every capacitor having one terminal grounded and a resistor connected in general between every pair of nodes. The method utilizes an iterative minimization technique for the realization of short‐circuit admittance functions. A degree of flexibility in the topology is possible in that certain of the resistors can be eliminated. The synthesis method is particularly suitable for integrated circuits as it yields structures with the minimum value of total capacitance as well as the minimum number of capacitors.
On the mathematical formulation of the wiring problem
Authors: Van Lier Ralph Marinus C. , Otten H. J. M.
Published: June 2007

The wiring problem is usually transformed into a graphtheoretical analysis‐synthesis problem. For a practical algorithm it is necessary that certain constraints are taken into account in the construction of the respective graph. These constraints originate from the desire to place terminals—eventually in a previously determined sequence—at the periphery of the board or the wiring layer of an integrated circuit (IC). For printed boards we can also have some demands regarding the sequence of contacts and the side on which the components have to be placed.

The purpose of this paper is to show how these requirements, which are indispensible for a proper printed board layout, can be examined. Some of these requirements have not appeared in literature before. The inquiry consists of two separate tests, each eventually combined with modification steps. The details of these modifications are not a subject of this paper. In the last section the content of this paper is compared with other publications in this field.
Approximation of a phase characteristic by the transfer‐function of a digital filter
Authors: Unbehauen Rolf
Published: June 2007

A method is presented for determining the transfer‐function H(z) of an asymptotically stable digital filter on the basis of a prescription for phase in a certain frequency interval. The restrictions to be imposed on the prescribed phase function are investigated. It is possible to make amplitude prescription in addition. The results will be demonstrated with the aid of a simple example.
On rlc network matrices
Authors: Fialkow Aaron D.
Published: June 2007

A generalization of the coefficient conditions which hold for an RLC network as well as of the paramount property obeyed by the matrix of a resistance network is derived. This result is a property of either the nodal or mesh matrices for either the admittances or impedances of a general RLC network. It states that if P is any principal minor or such a matrix and Q any other minor constructed from the same rows (columns) as P then P, P + Q, P–Q are rational functions of the complex frequency variable which, before cancellation of common factors, have only non‐negative coefficients.
Higher derivative network sensitivities using adjoint network
Authors: Seth A. K. , Roe P. H.
Published: June 2007

Higher derivative sensitivity coefficients for a lumped linear time‐invariant networks are derived by an extension of the method used by Richards to calculate second derivative sensitivity coefficients. A computer algorithm to generate these coefficients efficiently is provided together with array space and the number of operations required at each stage. Extensions of the above approach for networks containing distributed and nonlinear elements are also discussed. Finally, time domain sensitivity results are derived and the corresponding changes in the computer algorithm indicated.
Applications of the discrete green's function concept in circuit theory
Authors: Gruner L.
Published: June 2007

It is shown that the analysis of a network comprising passive, active, reciprocal, nonreciprocal, lumped or distributed elements and excited by voltage and current sources distributed throughout the network can be very effectively undertaken with the aid of the discrete Green's function concept if the network may be represented as a chain of sub‐networks having known two‐port parameters and if independent sources are only present at ports joining these sub‐networks.

The procedure offers computational advantages when the number of sub‐networks is large and moreover, it may be applied to the solution of other problems which are described by a large system of linear equations, when the coefficients form a band matrix.
A synthesis method for power network extension
Authors: Szendy Károly
Published: June 2007

In this paper the synthesis problem of power‐network extensions will be studied under the assumption that the loads are deterministic. The extended network satisfying conditions on the branch voltage limits will be optimized by the minimization of the network ‘first‐cost’. Useful notions such as network extension impedance and extension coefficient matrices will be introduced to describe the effect of network extensions. Two optimization methods will be presented. In the first one the cost function is linear and the constraints appear in the form of simple fractions. In the second method the cost function is assumed to be quadratic but the constraints are linear. In the latter case the extensible branches have to form a tree. It will be shown that sequential unconstrained optimization techniques can be applied in both cases.
Modeling of coupled multiconductor microstrip‐like transmission lines
Authors: Bálint L.
Published: June 2007

Circuit models of multiconductor, longitudinally homogeneous guides having cross‐section of arbitrary geometry and filled with several different dielectric materials are investigated in the framework of the TEM and quasi‐static approach.

The existence of uncoupled and orthogonal TEM modes is established providing a good approximation for multi‐conductor low‐loss lines having inhomogeneous dielectric filling. Utilizing these modes the lossy Z and Y matrices are derived. The circuit models can be used for frequency‐domain analysis of lumped‐distributed circuits.
The allowed varactor parameter tolerances for the electrical tunability of two microstrip parametric amplifiers
Authors: Sirkeinen Y. K.
Published: June 2007

The variations in varactor parameters which can be compensated by the electrical re‐tuning of two specific amplifiers have been studied using a digital computer. The designs of two different microstrip parametric amplifiers were at first optimized with respect to the bandwidth. Then after changing the varactor parameters, pumping and biasing conditions were optimized in order to attain maximum flat gain bandwidth within certain acceptable limits for gain and frequency. The results show that considerable variations can be compensated electrically.
Fourier coefficient design of stepped impedance transmission line networks
Authors: Rhodes J. D.
Published: June 2007

The conventional method of designing stepped impedance transmission line networks from gain functions requires the use of a factorization process to obtain a passive input impedance, and then the application of Richards Theorem to determine the element values. A new technique is presented based upon the determination of the Fourier coefficients of the return loss function from which the element values may be obtained immediately for the minimum phase reflection coefficient without any factorization process or synthesis procedure. It is believed that this new technique may be extended directly to the design of mixed lumped‐distributed transmission line networks whereas the conventional approach may not.
Networks containing periodically operated switches: A state space approach
Authors: Orfei R. , Pallottino G. V.
Published: June 2007

A state space analysis is given of the networks containing periodically operated switches, by using a new approach based on the concept of time constant multiplication rather than on the conventional concept of resistance multiplication.

The transfer function of two‐port networks containing P.O.S. is derived from a state model that does not require a detailed topological analysis of the network.

The number and the location of the switches is discussed with particular reference to the problem of their minimization.

Experimental results are given by illustrating an application of variable filters to the realization of a spaceborne spectrum analyzer.
A method of graphical approximation in synthesis of rc distributed networks
Authors: Řiazek Stanislav
Published: June 2007

The approximation problem in synthesis of RC distributed networks is discussed. The synthesis methods based on transcendental frequency transformations are considered. A method of graphical approximation of a required network function magnitude is proposed. The modified frequency is introduced to ensure asymptotic behaviour of the logarithmic plots and the relevant design‐charts are presented. They enable us to find out the locations of zeros of normalized factors from the prescribed values of the magnitude and frequency. A method of two‐step analytical approximation is also included. The proposed methods are very useful for the preliminary approximation that saves time for further numerical procedures by a computer. The methods presented are illustrated by an example.
On enumerating the trees of a ladder network
Authors: Johnson D. E. , Johnson J. R.
Published: June 2007

Ladder network functions are obtained using signal flow graph and flow graph techniques. A procedure is developed, using a flow graph analysis, for enumerating by inspection and without duplication the trees of the graph of a ladder network.
Generation and classification of single amplifier filters
Authors: Sedra Adel S.
Published: June 2007

A unified approach is presented for generating configurations for circuits containing one operational amplifier together with RC elements and capable of realizing a general second‐order voltage transfer function. Systematic application of the generation procedure leads to various single amplifier biquads with the known circuits, as well as some new ones, obtained as special cases. The insight gained from the generalized approach as well as the results of a general sensitivity analysis (including the effects of the amplifier limited bandwidth) offer a method for categorizing and classifying single amplifier filters. The different filter classes are illustrated and compared with the aid of extensive design tables. General equations for the effect of the amplifier limited bandwidth are also given.
Infinite networks of positive operators
Authors: Zemanian A. H.
Published: June 2007

Infinite resistive networks have recently been analyzed by H. Flanders. The present work is an extension of Flanders results in three directions:

It analyzes the more general case where the resistances in the network are positive bounded linear operators on a Hilbert space H and the currents and voltages are members of H.

An infinite number of sources is now allowed.

The network is permitted to have finite loops of doubly infinite paths consisting entirely of short circuits.

Conditions are developed under which existence and uniqueness theorems for the set of branch currents can be stated.

These conditions include the requirement that all branch resistances be either zero or invertible. The situation where some or all of the resistances have nontrivial null spaces is also considered. In those cases where the branch currents need not be unique for a given set of sources, the difference between two possible current distributions can be characterized as a current distribution that produces zero voltage drops in all branches. An application to time‐varying resistive networks containing switches is also given.
Low‐pass filters with maximally flat magnitude beyond the origin and arbitrary transmission zeros
Authors: Rabrenović D. , Jovanović V.
Published: June 2007

An analytical procedure for generation of a special type of critical monotonic magnitude characteristic, having maximal flatness at a given frequency ω0 beyond the origin, with arbitrary transmission zeros, is presented. Compared with the known filters with maximally flat magnitude at the origin and the same transmission zeros, the new filters show distinct improvement in the cutoff performance.
Effect of resistive losses on superconductive multimode oscillators
Authors: Parmentier R. D. , Costabile G.
Published: June 2007

Arrays of negative resistance tunneling elements can support multimode, multistate oscillations and have been proposed for information processing applications. Published studies have analyzed nonresonant mode interactions by treating the nonlinear tunneling currents as small perturbations on the time‐average behaviour of a linear lossless array, but they have neglected the effects of linear resistive losses. For an array of superconductive tunnel junctions, these resistive losses, treated using the same perturbation formalism, are shown to give rise to mode combinations in which some modes have negative energies, leading to the conclusion that such mode combinations cannot exist physically. Order of magnitude quantitative estimates indicate that such mode limiting effects might well occur in practical arrays and suggest how the array geometry might be modified to minimize these effects.
Symmetrical state matrices for 2‐element‐kind networks
Authors: Narraway J. J.
Published: June 2007

General state matrix formulations for CR, LR and LC networks which are, respectively, symmetrical, symmetrical and skew symmetrical are given.
A three‐terminal piecewise‐linear modelling approach to dc analysis of transistor circuits
Authors: Hajj I. N. , Roulston D. J. , Bryant P. R.
Published: June 2007

The simulation of electronic circuits by computer has become an important part of present‐day circuit analysis and design, especially in the area of integrated circuit design. One of the goals in computer simulation of integrated circuits is to have a program ‘package’ for which the input consists of chip fabrication data (mask dimensions, impurity profiles, material data such as carrier lifetimes) and the output displays the complete circuit response. This requires both an efficient modelling approach and a fast circuit analysis method.

In this paper a simulation method is described which generates dc responses (in the form of operating points or transfer characteristics) of transistor circuits directly from physical parameter data. The basis of the method is a two‐dimensional piecewise‐linear approach to the dc modelling of bipolar transistors. The model is directly used in a piecewise‐linear circuit analysis program to simulate the dc response of a given circuit.
Synthesis of n‐port active rc networks with a minimum number of capacitors
Authors: Stamenković Borivoje B.
Published: June 2007

A new and practical synthesis procedure is presented for the realization of an arbitrary n × n matrix of real rational functions of the complex frequency variable as the short‐circuit admittance matrix of a transformerless active RC n‐port network. The realization requires a theoretically minimum number of capacitors p, where p is the degree of the matrix, and no more than (n + p + 1) grounded finite‐gain phase‐inverting voltage‐controlled voltage sources. All the capacitors and ports are grounded.

The freedom implicit in the synthesis procedure allows the inclusion of constraints on the passive element values. Furthermore, in special cases the realization is achieved with a reduced number of conductances and voltage‐controlled voltage sources. The synthesis procedure is simple to apply and can readily be implemented on a digital computer. Several examples are given.
A note on passivity and losslessness
Authors: Levan N.
Published: June 2007

This note gives new necessary and sufficient conditions for a linear system to be passive or lossless. It will be shown that, by using the theory of operators on an indefinite J(t)‐Hilbert space, both the passivity and isometric conditions for an operator to be lossless can be combined into a single condition—namely an operator is lossless if and only if it is J(t)‐contractive.
High‐frequency limitations of rc‐active filters containing simulated‐l and fdnr elements
Authors: Bruton L. T. , Haase A. B.
Published: June 2007

High quality RC‐active filters may be realized using inductance‐simulation or FDNR‐synthesis techniques where generalized immittance converters (GIC) are the basic active two ports of the synthesis. The deterioration of the magnitude transfer function |T(jω)| at high frequencies is determined in terms of the gain bandwidth products B of the operational amplifiers employed within the GIC's. The basis of the method is to extend Blostein's lossless LC‐twoport tolerance by determining the magnitude and phase errors of the simulated‐inductance or FDNR elements.
Current and voltage graphs of a composite graph
Authors: Fischer Hans Dieter
Published: June 2007

From a given composite graph two graphs are derived, which can be interpreted as current and voltage graphs, respectively. It is shown that a complete tree of both graphs is a directed tree of the composite graph. Thus the generation of directed trees is reduced to the generation of complete trees. The matrix belonging to the composite graph is decomposed in the incidence matrices of the current and voltage graphs and in a diagonal matrix whose elements are given by the edge‐weights of the composite graph. The number of directed trees in a composite graph is determined using the incidence matrices of both graphs.
The inverse laplace transform of a function of the m‐derived filters
Authors: Chen Wai‐Kai
Published: June 2007

The inverse Laplace transformation of a transfer function of the m‐derived wave filters is presented. Using this result, the transient responses of a composite wave filter and a distributed amplifier using m‐derived filter sections are derived. They are shown to be expressible as sums of integrals involving generalized hypergeometric functions in the same way that the solutions for other wave filters involve Bessel functions.
On the realization of gyrators by nullors and resistors
Authors: Adams K. M. , Deprettere E.
Published: June 2007

It is proved that for the realization of a gyrator by nullors and resistors, at least two nullors and at least two resistors are needed. A generalization is the result that any n‐port network possessing both an impedance and an admittance matrix and consisting of nullors and resistors must contain at least n resistors.

It is conjectured that a realization of a gyrator with only two nullors requires four resistors and a realization of a gyrator with only two resistors requires three nullors.
Realizable filters which give zero intersymbol interference in an fsk system
Authors: Tomlinson Martin
Published: June 2007

Filter constraints are given which enable filters to be designed which give zero intersymbol interference at the output of the frequency discriminator in an FM system; these constraints are developed in the frequency domain which enables satisfactory noise bandwidths to be obtained. The results are not limited to a particular deviation ratio and are applicable to both continuous and discontinuous phase systems. Some examples are given including a practical IF filter design for a 4.8 K bit/sec, 250 kHz centre frequency, 0.8 deviation ratio system. The noise bandwidth of this filter is 5.72 kHz and it is shown that the minimum possible obtainable noise bandwidth is 4.63 kHz.
Synthesis of low‐pass double‐ladder operational amplifier network with prescribed pole sensitivities
Authors: Murthy N. , Aatre V. K. , Ramachandran V.
Published: June 2007

This paper discusses the realization of low‐pass filters having a pair of complex conjugate poles by a multiple feedback RC operational amplifier network. When the pole sensitivity with respect to the amplifier gain is prescribed, it is shown that the gain can be determined and then the synthesis proceeds in a way similar to the one with an infinite gain amplifier. This structure uses fewer passive elements as compared to Hakim's structure and the quadratic sensitivity index is closer to its theoretical minimum.
The equidistant linear phase polynomial for distributed and digital networks
Authors: Fahmy M. F. , Rhodes J. D.
Published: June 2007

A closed form expression for the recurrence formula for the generation of polynomials whose phase interpolates to linear characteristics at equidistant frequencies is presented. This polynomial may be used directly in the design of both distributed and digital networks and, due to the recurrence formula, readily generated. Since the complete proof of this formula is extensive and not required for normal use of this polynomial, it has been outlined in an Appendix.
A memristive circuit model for p‐n junction diodes
Authors: Chua Leon O. , Tseng Chong‐Wei
Published: June 2007

A new simple lumped circuit model for junction diodes is presented. The model contains only 4 elements; namely, 2 controlled current sources, a nonlinear capacitor, and a memristor. Each component bears a simple relationship with the physical operating mechanisms inside the diode. The model is shown capable of simulating realistically the diode's dynamic behaviours under reverse, forward, and sinusoidal operating modes. Both the storage time and the fall time of the diode can be accurately predicted. The model is also shown capable of mimicking various second order effects due to conductivity modulation. In particular, the model is shown to exhibit a predominantly capacitive incremental impedance under small forward bias and a predominantly inductive impedance under large forward bias. Moreover, it includes the standard two‐capacitor model as a special case.
High‐frequency comparison of gic‐simulated inductance circuits
Authors: Bruton L. T. , Lim J. T.
Published: June 2007

It is shown that there is a significant difference in the high‐frequency behaviour of two well‐known generalized immittance converter realizations of simulated inductance. One of the realizations yields a Q factor that is highly sensitive to mismatch of amplifier bandwidths whereas the alternative realization can be designed to give a Q factor that is highly insensitive to this mismatch.
Bipartite network associated with optimal pivoting problem
Authors: Shirakawa Isao , Kyan Seiki , Ozaki Hiroshi
Published: June 2007

The coefficient matrix of a fairly large system of equations is generally very sparse. Thus in the computer‐aided analysis of such a system of equations, of prime importance are the sparsity‐oriented solution and storage techniques. Motivated by this problem, in the present paper we first define a bipartite network associated with a given system of equations, and then discuss the problem of sparsity‐preserving pivot ordering with the use of the bipartite network.
On pole distribution in digital filters
Authors: Rahman M. H. , Fahmy M. M.
Published: June 2007

Due to the discrete nature of the coefficients the poles and zeros of a digital filter transfer function cannot, in general, be realized exactly. This paper introduces a new concept ‘pole sparsity factor’ as a measure of the maximum possible pole deviation after tuning, for the case of second order circuits. A new second order circuit that exhibits lower pole sparsity factor compared to presently available circuits with the same number of multipliers is presented.
CASCADE SYNTHESIS OF MONOLITHIC CRYSTAL FILTFRS POSSESSING FINITE TRANSMISSION ZEROS
Authors: Dillon C. R. , Lind L. F.
Published: June 2007

A simple method for the synthesis of bandpass or bandstop filters possessing finite transmission zeros as a cascade of shunted double‐resonator monolithic crystal filter (MCF) sections is given. The lowpass or highpass prototype transfer function is synthesized as a cascade of MCF prototype sections for which explicit expressions for the element values are given. Application of the narrow‐band lowpass to bandpass frequency transformation to the prototype network then yields a physically realizable filter with the desired bandpass or bandstop response. An example of the synthesis of a bandstop filter is given to illustrate the approach.
Optimized design of cascaded active RC bandpass filters
Authors: Novák Mirko , Hruby Jaroslav
Published: June 2007

The synthesis of RC active filters composed of a chain of standardized selective functional blocks (SSFB's) is discussed. The rules for the optimal or quasioptimal choice of the SSFB's in the chain which leads to an increase of dynamic ratio and noise suppression are given. The design procedure of the SSFB's having very accurate and temperature stable parameters is described.
An electronically tunable RC active filter
Authors: Swamy M. N. S. , Rao K. Sankara
Published: June 2007

An RC active filter with embedded FET switches is presented for the realization of a general second order filter. The filter consists of minimal number of capacitors, two differential input dual output operational amplifiers, fixed resistors and resistors connected as potential dividers. The network has low Q and ω0 sensitivities; further, the finite bandwidth of the operational amplifiers has negligible effect on the Q of the filter.

The introduction of FET switches in the network results in frequency scaling and consequently, the possibility of electronically tuning it. In addition, by switching the FETs by pulses of very low duty cycle, it is possible to obtain subaudio filters using resistive and capacitive components of smaller values than required for a conventional filter. Experimental results pertaining to the band‐pass case are also included.
On the active rc realization of rational admittance matrices with prescribed ranges of passive RC element values
Authors: Stamenkovič Borivoje B.
Published: June 2007

Following a review of methods for the synthesis of grounded multiterminal active RC networks when grounded finite‐gain voltage‐controlled voltage sources (VCVSs) serve as active elements a new result is presented. It is proved that an arbitrary short‐circuit admittance matrix can always be realized with prescribed ranges of passive RC element values.
Interdigital filters with a linear phase and a minimum attenuation in the passband
Authors: Garault Y. , Jarry P.
Published: June 2007

The purpose of this paper is to determine a new class of characteristic polynomials for interdigital filters with short‐circuited input lines. The corresponding transmission factor provides (n–2) zero derivatives of its group delay at the origin and the attenuation is nearly nullified in the passband.
Improved design of a multifeedback bandpass filter
Authors: Biey Mario , Premoli Amedeo
Published: June 2007

The multifeedback second‐order RC active filter is of considerable interest and has been studied extensively. Nevertheless, its behaviour has been in general analysed without making allowance for the non‐ideal characteristics of the embedded operational amplifier (OA).

This paper presents some formulas that can be used for improving the design of such a filter. They were derived on the basis of an OA model that takes into account both input and output resistances, unity‐gain frequency, and dc‐gain. They make use of algorithms characterized by a relative simplicity and quite a good approximation. Their application makes the filter easy to tune and usable for high frequencies, while at the same time the dependence of the Q‐value on temperature variations in the operational amplifier is minimized.

Two universal graphs are given in the text. They simplify the use of the new formulas in obtaining the analysis and the synthesis of the multifeedback second order filter. Experimental results that check the validity of the proposed formulas are presented.
Simplex analysis of grounded concave piecewise‐linear resistive networks
Authors: Blasi F. , Martinelli G.
Published: June 2007

The physical properties of the networks under consideration may be advantageously used for saving time and storage in analysing nonlinear networks. The algorithm proposed in the present paper represents an attempt in this direction. It concerns a particular class of piecewise linear resistive networks and it is based on a modification of the simplex as originally proposed by Dantzig.

The algorithm requires:

The analysis of the linear network obtained by the given one by replacing the nonlinear resistances by linear ones.

The application of the modified simplex.

This second step requires a number of arithmetical operations less than that necessary for analysing a linear resistive network having a number of nodes equal to the total number of break‐points of the nonlinear resistances.
Wave‐digital cascade synthesis
Authors: Nouta R.
Published: June 2007

The purpose of this paper is to demonstrate the possibility of a wave‐digital cascade synthesis. Each section, reciprocal as well as non‐reciprocal, being for instance the result of a cascade synthesis based on the factorization of the transfer matrix of an analogue lossless two‐port network, is translated into a wave‐digital realization. Except for the zero‐order sections, it is shown to be sufficient that each section is cascaded with one unit‐element in order to obtain an equivalent network which can be translated into wave‐digital form. It gives some insight in the price to be paid in terms of complexity of the realization if a perfectly general transfer function is to be realized in wave‐digital form.

By some examples it is shown how each structure which has been introduced can be ‘passified’ if it cannot be realized by a lossless structure.
Tables on sensitivity invariants and bounds for lossless two‐ports
Authors: Neirynck Jacques , van Bastelaer Philippe
Published: June 2007

For lossless two‐ports, the lower and upper bounds of the worst case sensitivity index and of the quadratic sensitivity index are derived from invariance of the sensitivity sums and of the stored reactive energy. Tables are given that summarize the main results.
Reactance extraction at the ports of the general reciprocal three‐port
Authors: Butterweck H. J. , Mecklenbräker W. F. G.
Published: June 2007

The following theorems are derived:

By means of suitable lossless, reciprocal two‐ports, any reciprocal three‐port with complex parameters can be transformed into a real three‐port.

Any desired reciprocal three‐port can be synthesized as a real three‐port with lossless, reciprocal two‐ports connected to its ports.
Design of active filters using double layer rc distributed lines
Authors: Neelakantan M. N.
Published: June 2007

Application of double layer RC distributed lines in the design of low‐pass, band‐pass and high‐pass filters is considered in this communication. Realization of these filters employing two double layer lines and a difference amplifier using dominant root approach is also presented.
Simultaneous canonic synthesis of two dual impedances
Authors: Belevitch V.
Published: June 2007

It is proved that two dual passive impedances Z and R2/Z (R real constant) each of degree m are simultaneously realizable by a lossless reciprocal 4‐port of degree 2m closed on two constant resistances. Moreover, the lossless reciprocal 4‐port is itself realizable as a cascade of such 4‐ports of degrees 2 and 4. These are extensions of the Bott–Duffin and Fialkow‐Gerst bridges but generally contain ideal transformers. As in Fialkow‐Gerst synthesis, the only algebraic equation to be solved is Z(p) + Z(–p) = 0 but, in contrast with Fialkow‐Gerst, the realization is minimal.