bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuartige Clustergerüste durch Umsetzung der ungesättigten Cluster Fe4(CO)11(μ4‐PR)2 mit Alkinen
Authors: Tilman Jaeger J. , Powell Anne K. , Vahrenkamp Heinrich 
Published: July 2007

AbstractDie ungesättigten Cluster Fe4(CO)11(μ4‐PR)2 (1–3, R = Ph, p‐Tol, t‐Bu) reagieren mit terminalen Alkinen primär unter Insertion des Alkins zwischen einem Phosphor‐ und zwei Eisen‐Atomen. Die Strukturanalyse von Fe4(CO)11(μ4‐PTol)[μ4‐P(Tol)‐CMeCH] und NMR‐Studien in Lösung zeigen, daß die Insertionsprodukte in Form von zwei Isomeren vorliegen, die sich durch die Orientierung des Alkins (PCRCHFe/PCHCRFe) unterscheiden und deren gegenseitige Umwandlung in Lösung sich durch Basen katalysieren läßt. Aus 3 entstehen zusätzlich und bevorzugt unter CO‐Abspaltung alkinhaltige Cluster mit einem neuartigen Fe4P2C2‐Gerüst, das sich von einer pentagonalen Bipyramide mit äquatorialer Fe2PC2‐Einheit ableiten läßt, wie die Strukturanalyse von Fe4(CO)9(μ3‐P‐tBu)[μ4‐P‐(tBu)CHCMe] belegt. Die primären Alkin‐Insertionsprodukte werden durch überschüssige Donorliganden [CO, P(OM)3, tBuNC] und durch Oxidation mit Iod leicht unter Abspaltung einer Eisencarbonyl‐Einheit zu den Clustern Fe3(CO)9[μ3‐μ3‐P(R)‐CHCR′PR] bzw. substituierten Derivaten davon abgebaut. Für diese beweist die Strukturanalyse der (PhPCHCMePPh)‐Verbindung die PCCP‐Verknüpfung und eine Seitwärtskoordination der C2‐Einheit an ein Eisen‐Atom. Der Abbau verläft mit P(OM)3 und tBuNC über die Substitutionsprodukte Fe4(CO)10L(μ4PPh)‐[μ‐P(Ph)CRCH], die ebenfalls in Form von zwei Isomeren mit unterschiedlicher CRCH‐Orientierung vorkommen.
Organische Synthesen mit Übergangsmetallkomplexen, 31. N‐Benzylketenimin‐Komplexe – Reaktivitätssteuerung von Additions‐ und Umlagerungsreaktionen durch unterschiedliche Metallreste
Authors: Aumann Rudolf , Heinen Heinrich 
Published: July 2007

AbstractN‐Benzylketenimin‐Komplexe, LnM[C6H5CH2N=C=C(OEt)‐C6H5] 3 [LnM = Cr(CO)5, Mo(CO)5, W(CO)5, Mn(CO)2CH3‐C5H4), Fe(CO)4] werden durch Addition von Benzylisocyanid an Carbenkomplexe 1 erhalten. Sie isomerisieren leicht unter 1,3‐N/C‐Wanderung des Benzylrestes zu 3‐Phenylpropannitril‐Komplexen 5. Die Umlagerungstendenz hängt stark vom jeweiligen Metallrest ab und läßt sich durch folgende Reihe charakterisieren: Mo > Cr > W ≫ Mn, Fe. Abfangreaktionen unter Addition protischer Nucleophile an 3 führen zu Aminocarben‐Komplexen 6. Abfangreaktionen mit weiterem Benzylisocyanid liefern Di‐(imino)indan und/oder Azetidinyliden‐Komplexe (11 und/oder 12 bzw. 13). Der Einfluß des jeweiligen Metallrests auf die Produktverteilung wird durch Konkurrenzversuche charakterisiert. An Chrom‐ und Molybdän‐Komplexen dominiert die Bildung von Di(imino)indanen, an Mangan‐ und Eisen‐Komplexen die Bildung von Azetidine,. Wolfram‐Komplexe nehmen eine Mittelstellung ein und bilden beide Systeme in etwa gleichen Anteilen.
Metall‐Komplexe mit biologisch wichtigen Liganden, XLVII. Kupfer‐, Nickel‐, Palladium‐ und Platin(II)‐Komplexe mit C‐Allylglycin und N‐(Diphenylmethylen)‐C‐allylglycinester
Authors: Steiner Norbert , Nagel Ulrich , Beck Wolfgang 
Published: July 2007

AbstractC‐Allylglycin reagiert – abhängig vom pH‐Wert – mit Ni‐, Cu‐, Pd‐ und Pt(II)‐Salzen zu den trans‐N,O‐Bischelat‐Komplexen M[NH2CH(CH2CHCH2CO2]2 1 (M  Cu, Ni, Pd) oder zu N,η2‐C,C‐Chelat‐Komplexen Cl2MNH2CH(CO)2R)CH2C‐(R)CH2 2 (R  H, Me; M  Pd, Pt). N‐(Diphenylmethylen)‐C‐allylglycinester setzen sich mit Na2PdCl4 oder PtCl2 zu den ortho‐metallierten Komplexen 3 um, in denen der Ligand dreizähnig über das ortho‐C(Phenyl)‐Atom, das Iminostickstoff‐Atom und die C  C‐Doppelbindung koordiniert ist. Die Molekülstrukturen von 2a und 3c wurden röntgenographisch bestimmt.
Addition von Pentacarbonylrhenat an koordiniertes Benzol: Ein σ,π‐verbrückter, dynamischer Cyclohexadienyl‐Komplex, (OC)5Re‐μ‐(η1:η5‐C6H6Mn(CO)3
Authors: Niemer Burkhard , Steimann Manfred , Beck Wolfgang 
Published: July 2007

Addition of Pentacarbonylrhenate to Coordinated Benzene:A δ,π‐Bridged, Fluxional Cyclohexadienyl Complex, (OC)5Re‐μ‐(η1:η5‐C6H6)Mn(CO)3Nucleophilic addition of pentacarbonylrhenate to coordinated benzene in [(η1:η5 ‐C6H6)Mn(CO)3]+ gives the η1:η5‐cyclohexadienyl‐bridged title compound 1. The structure of 1 has been determined by X‐ray analysis. 1 is the first example of fluxional behaviour in η5‐cyclohexadienyl complexes.
Brückenkopf‐gekoppelte Bicyclo[1.1.1]pentane: Synthese und Struktur
Authors: Bunz Uwe , Polborn Kurt , Wagner Hans‐Ulrich , Szeimies Günter 
Published: July 2007

AbstractDie durch Azoisobuttersäuredinitril ausgelöste Radikalkettenaddition von einigen organischen Disulfiden 2 an [1.1.1]Propellan (1) erbrachte neben den „Monoaddukten”︁ 3 und neben polymerem Material auch die kopplungsdimeren, ‐trimeren und ‐tetrameren Bisthioether 4, 5 und 6 in Ausbeuten, die vom 2:1‐Verhältnis abhingen. Während die Reduktion von 4a mit Lithium in Ethylamin zum Dithiol 4e führte, ließ sich der Kohlenwasserstoff 4g durch Reduktion von 4c gewinnen. Die Röntgenstrukturanalysen von 4a und dem entsprechenden Bissulfon 4f zeigten als auffallendes Merkmal die vorhergesagte kurze Bindung zwischen C‐1 und C‐1′. Eine MNDO‐Studie an unterschiedlich Brückenkopf‐substituierten 1,1′‐Bibicyclo[1.1.1]pentanen 4g–4k machte deutlich, daß die Struktur des Kohlenstoffgerüsts von 4 durch die Substituenten nur unbedeutend beeinflußt wird.
Syntheses and Reactions of Glycosylcobaloximes
Authors: Ghosez Anne , Göbel Thomas , Giese Bernd 
Published: July 2007

AbstractGlycosylcobaloximes 6a, b are synthesized by reactions of glycosyl bromides 4a, b with the cobalt(II) complex 5 under reducing conditions. Under irradiation, α‐glycosylcobaloximes 6a, b isomerize to give the β isomers 9 and 15, respectively. These isomerization reactions occur via radicals that can be trapped by nitroso alkane 12, nitrogen monoxide, and alkenes. Reactions with alkenes 17 yield addition products 18 and/or substitution products 19. The product ratio 18:19 depends on the electron‐withdrawing ability of the substituents of the alkenes.
Reaktionen der Dicyanessigsäureester mit Alkoholen, Thiolen und Halogenwasserstoffsäuren
Authors: Neidlein Richard , Kikelj Danijel 
Published: July 2007

AbstractDicyanessigsäureester 1 oder deren Alkalisalze 1a reagieren mit überschüssigen Halogenwasserstoffsäuren zu den 3‐Amino‐3‐halogen‐2‐cyanacrylsäureestern 2. Bei der Reaktion von 1 mit Alkoholen unter Rückfluß werden 3‐Alkoxy‐3‐amino‐2‐cyanacrylsäureester 3a–c und 4a gebildet. Mit Thiolen entstehen die entsprechenden 3‐(Alkyl‐/Arylthio)‐3‐amino‐2‐cyanacrylsäureester 3j, k und 3‐(Alkyl‐/Arylthio)‐3‐amino‐2‐cyanthioacrylsäure‐S‐alkyl/arylester 4b, c. 2, 3 und 4 weisen eine Enaminstruktur mit cis‐ständiger Amino‐ und Estergruppe auf.
Untersuchungen zur Chemie von Isoindolen und Isoindoleninen, XXXI. 4,5,6,7‐Tetrachlor‐ und 4,5,6,7‐Tetrabrom‐2H‐isoindol
Authors: Kreher Richard P. , Herd Karl Josef 
Published: July 2007

AbstractDie kristallinen 2H‐Isoindole 4b werden aus substituierten 2‐Methylsulfonyl‐2,3‐dihydro‐1H‐isoindolen 3 durch Basen‐induzierte Eliminierung von Methansulfinsäure synthetisiert. Die Halogenatome am carbocyclischen System bewirken – verglichen mit dem Grundkörper – eine beträchtliche thermische Stabilisierung und chemische Desaktivierung. Die spektroskopischen Eigenschaften der o‐chinoiden Hetarene 4b wurden untersucht.
Darstellung und Reaktionen Trifluormethylchalkogenyl‐substituierter Alkine
Authors: Haas Alois , Krächter Hans‐Udo 
Published: July 2007

Abstract(Trifluormethylchalkogenyl)alkine 1 werden durch Reaktion entsprechender Bromalkine mit CuECF3 (E = S, Se) erhalten. Lediglich Bis(trifluormethylthio)ethin (1a) wird nicht direkt, sondern aus BrCHCHBr über die Zwischenstufen CF3SCHCHSCF3, CF3S(Br)CHCH(Br)SCF3 und anschließende HBr‐Eliminierung synthetisiert. Photolyse und Zersetzung von 1a in Gegenwart von (C6H5)P führen zu den Thiophenderivaten 3a,b. Bei der Pyrolyse von 1a entsteht zusätzlich noch das 1,4‐Dithiin 3c, und die Brom‐addition liefert das cis/trans‐Isomerengemisch 2a,b. Cycloadditionen an Dicyclopentadien, Hexachlorcyclopentadien, Anthracen, Tetrachlor‐5,5‐dimethoxycyclopentadien, Tetraphenylcyclopentadienon und Dibromcarben führen zu den Homocyclen 4a–e und 5a. 1,3‐Dipolare Additionen von 1a an Diphenylnitrilimin, PhN3 und R2CN2 (RH, CH3, C6H5) liefern die Heterocyclen 6a,c und 7b–e. Pyrazol 7e zerfällt in 7f und 5b. Die Furanderivate 9a,b werden aus 1,3‐Oxathiolonen 8a,b und 1a gewonnen. Bei Umsetzungen von 1a mit S4N4 bzw. SO3 entstehen die Siebenringe 10 bzw. 11.
Synthesen cyclischer und acyclischer 1,4‐Chinonhydrazone mit Norcaradien‐ und Cycloheptatrien‐Partialstruktur
Authors: Neidlein Richard , Jäschke Uwe 
Published: July 2007

Syntheses of Cyclic and Acyclic 1,4‐Quinone Hydrazones with Norcaradiene and Cycloheptatriene FragmentsThe syntheses of different triazine and azo dyestuffs 2a–c, 4a, b, 5a, b, and 6c are described.
On state‐space synthesis of reciprocal n‐ports
Authors: Trón T. 
Published: July 2007

AbstractThe paper considers the state‐space synthesis of reciprocal n‐ports with a minimum number of reactive elements. After formulating the synthesis problem new procedures are given for the lossless and for the passive cases which use a directly determinable reciprocal minimal realization as starting point. The methods are presented in terms of admittance matrices and then restated for impedance, hybrid and scattering matrix synthesis.
State–space formulation of linear circuits containing periodically operated switches
Authors: Köksal M. , Tokad Y. 
Published: July 2007

AbstractThe state–space formulation of linear circuits containing periodically operated switches requires one to obtain the state and output equations. Further, it requires one to obtain the switching equations where discontinuities in the state variables occur at a switching instant. A new method for the computation of the state and output equations is given. Further, a procedure is described to obtain the switching equations, in the most general form, at a switching instant. Examples are given to illustrate these methods in finding the state, the output and the switching equations.
Sensitivity of third‐ and higher‐order filters
Authors: Roy S. C. Dutta , Bhargava D. K. 
Published: July 2007

AbstractFor any realization of a network function F(s) = N(s)/D(s), the sensitivities that can be most readily calculated are those of the coefficients in N(s) and D(s). A simple relationship is derived that enables one to calculate the root (pole and zero) sensitivities of F(s) in terms of the coefficient sensitivities. The root sensitivities, in turn, enable one to calculate the root pair Q and root frequency sensitivities, which can be used to characterize and compare different realizations of F(s). Application to 3rd‐ and 4th‐order filters reveals formulations that are more elegant than those already known in the literature.
Determining the periodic response of nonlinear systems by a gradient method
Authors: Nakhla M. S. , Branin F. H. 
Published: July 2007

AbstractFor systems of differential equations of the form ẋ = f(x) or x = f(x, t), a periodic response may be identified by the requirement that x(kT) = x(0), where k = 1, 2, … and T is the period, x(0) = x0 being the initial‐condition vector. We describe a gradient method for finding this x0 vector by minimizing the square magnitude of the ‘discrepancy vector’ δ(x0) = x(T)–x0. The gradient of the scalar function P(x0) = δt(x0)δ(x0) with respect to x0 is calculated by one full‐period forward integration of the original differential equation to obtain δ(x0), and then one full‐period backward integration of the adjoint variational equations, using δ(x0) as the initial‐condition vector. The gradient of P(x0) is then twice the adjoint discrepancy vector. We use Fletcher's method of optimization to minimize P(x0).
Pole‐zero sensitivities of a digital filter due to parameter quantization
Authors: Stojić M. R. , Stojić R. M. 
Published: July 2007

AbstractAn analytical procedure for the sensitivity analysis of digital filters is presented. The procedure applies to the sensitivity investigation of digital‐filter poles and zeros due to parameter quantization. Suitably defined sensitivities and a computer‐aided technique, presented in the paper, allow a rapid evaluation of displacements of digital‐filter poles and zeros due to parameter quantization in different realizations of a given digital filter.
Generalized bessel polynomials with application to the design of bandpass filters with approximately flat group delay response
Authors: Fahmy M. F. 
Published: July 2007

AbstractThe continued fraction expansion of the ordinary Bessel polynomials is modified by replacing the complex frequency variable p by p/(1+γp), where γ=⩾0. The resulting polynomials, when a reactance transformation is applied, are capable of providing bandpass filters with an approximately flat group delay response.
Tapered‐magnitude bandpass distributed‐network transfer functions
Authors: Mokari‐Bolhassan M. E. , Ku W. H. 
Published: July 2007

AbstractSloped commensurate transmission‐line functions realizable with stubs and cascaded lines 1/8 wavelength long are presented. These functions may be applied to synthetizing matching networks required for slope compensation in microwave amplifiers. Examples for the broadband design of 7–14 GHz chip 1 μm gate f.e.t. and 4–8 GHz packaged f.e.t. amplifiers are given.
Determination of initial conditions in active RLC networks
Authors: Köksal M. , Tokad Y. 
Published: July 2007

AbstractA new method is described of determining the initial values of state variables in active RLC networks. This method utilizes neither the conservation principle of charges and fluxes nor the theory of distributions. An RLC active network is assumed to be formed at t = 0 by joining or disconnecting the elements that are contained in it, this operation being performed by the use of a set of switches. The new method is based on the consideration of switches as independent sources, and the state equations are extended to cover this situation, and their solution at t = 0+ gives the initial conditions that have been sought. Further, the new method is applicable to any state‐space formulation techniques used.
Microwave bandpass filters consisting of rectangular waveguides with 1‐dimensional offsets
Authors: Kühn E. 
Published: July 2007

AbstractThe computer‐aided analysis and design of direct‐coupled and quarter‐wave‐coupled bandpass filters utilizing monomode rectangular waveguides with 1‐dimensional offset discontinuities are described. The equivalent networks of these discontinuities, which consist of a shunt reactance and additional transmission lines connected at both sides, have been derived from the rigorous field‐theoretical investigations of E‐plane and H‐plane displacements in rectangular waveguide. Both network elements are tabulated in terms of geometry and wavelength with fine steps to allow accurate interpolation by means of computational methods, Simple design formulae for the filter geometry as a function of the electrical specifications are given which are based upon narrow‐band approximations. The analytical relationships required for a computer simulation of the filter's wide‐band performance are summarized. The predicted frequency characteristics showed such close agreement with the experimental results obtained on two X‐band filter models that neither tuning elements in the waveguide sections nor final adjustments of the offset widths had to be provided.
An optimal design of RC active filters using grounded capacitors
Authors: Abougabal M. S. , Bhattacharyya B. B. , Swamy M. N. S. 
Published: July 2007

AbstractIt is desirable, from the point of view of integration, to have all the capacitors grounded in RC active filters. Recently, such a network was reported with only a preliminary design procedure. An optimal design is presented in this paper for the above network. The new design leads to a simpler configuration, simultaneously minimizes the worst‐case deviation in both the pole‐Q(Qp) and the pole frequency ωp and also guarantees that the network is free from unstable modes of operation during activation. Although this design is based on Qp and ωp, it is also suitable for notch and allpass sections. It is shown that the gains of the operational amplifiers (o.a.s.), controlling the poles of the filter, can all be made equal to (4Q2p‐1)1/3; this choice of the gains minimizes the effect of the finite bandwidths of the amplifiers on Qp and ωp. A simple scheme is proposed to compensate for this effect. The effect of compensation on the zeros, in the case of notch and allpass sections, is also studied. It is found that the effect on the notch frequency is negligible, while, for allpass filters, compensation for the poles automatically provides compensation for the zeros. A simple tuning scheme using only resistors is also presented, and the theoretical results are verified experimentally.
A general method for small‐signal circuit analysis considering thermal effects
Authors: Conte G. 
Published: July 2007

AbstractIt is well known that the behaviour of integrated circuits is strongly affected by thermal feedback. A general method for evaluating, by linear analysis, the complete circuit performance is described that considers these effects. The procedure can easily be implemented using only well known computer programs for the circuit analysis. Simple models for a number of devices (diodes, transistors and f.e.t.s) used in integrated circuits are given. Examples, using the circuit‐analysis program ECAP, are shown.
A nonlinear macromodel for operational amplifiers
Authors: Weil P. , McNamee L. P. 
Published: July 2007

AbstractA general‐purpose nonlinear macromodel of an operational amplifier is presented. All element values can be derived directly from typical specification sheets eliminating any testing to determine model parameters. The model simulates the following characteristics: voltage and current offsets, input impedance, nonlinear input bias currents, gain, multiple poles, nonlinear slew, common‐mode gain, voltage and current limiting and output impedance.
1‐ports with orthonormal properties
Authors: Czarnecki L. S. 
Published: July 2007

AbstractThe paper deals with the problem of finding the immittance functions of a 1‐port for which, in the case of periodic signals of Ω frequency, the voltage and current are orthogonal to one another, and in which the voltage and current have the same norms, i.e. they are related as a pair of Hilbert transforms. The need for the construction of such 1‐ports arises, for example, in connection with the problem of the measurement of the reactive power of nonsinusoidal waves. Three sets of network functions have been found for the networks in which input and output signals are pairs of Hilbert transforms, and it has been proved that one of them is a set of positive‐real and reactance functions, and that one is a set of transfer functions of all‐pass networks composed of orthonormal 1‐ports.
Use of function elimination filters to reject quasideterministic interference in ask systems
Authors: Plotkin E. 
Published: July 2007

AbstractThe use of the function filtration method to increase immunity to interference in ask systems is discussed. To achieve increased immunity, a function elimination filter (f.e.f.) was constructed to eliminate any sine‐wave interference (s.w.i.) with a priori unknown parameters. When there is no random noise, such a filter provides a zero error probability, in spite of the existence of s.w.i. It is shown that there exist some situations when the use of an f.e.f. provides an error probability less than that achieved by a matched filter (m.f.), even if the input process includes both s.w.i. and random noise.
Noise minimization in RC‐active filters using generalized impedance converters
Authors: Ramakrishna K. , Bruton L. T. 
Published: July 2007

AbstractA procedure has been given for minimizing the total output noise of a Generalized Impedance Converter (GIC), subject to constraints dictated by signal handling capability of the Operational Amplifiers and ease of microcircuit fabrication. The noise reduction is achieved only by the adjustment of RC elements of the GIC, and the total output noise after optimization in the example cited is close to the theoretical lower limit. The output noise of a higher‐order filter can be reduced by RC‐optimizing the individual GIC's of the active realization. Experimental results on a 20–24 kHz channel bank band‐pass filter demonstrate the effectiveness of the above procedure.
Piecewise‐linear modelling and simulation of nonlinear networks
Authors: Chien Ming‐Jeh 
Published: July 2007

AbstractThis paper presents a method which combines the modelling and simulation of a nonlinear network together. The main idea is to divide the rectangle of interest into simplices by imposing a fixed ordering. It turns out that the creation of a piecewise‐linear model and the computation of an approximate solution are greatly simplified because of the use of simplices. Some examples show that it is possible to apply the method to ‘fixed point’ problems and other types of problems.
Yield estimation for efficient design centring assuming arbitrary statistical distributions
Authors: Abdel‐Malek H. L. , Bandler J. W. 
Published: July 2007

AbstractBased upon a uniform distribution inside an orthocell in the toleranced parameter space, it is shown how production yield and yield sensitivities can oe evaluated for arbitrary statistical distributions. Formulae for yield and yield sensitivities in the case of a uniform distribution of outcomes between the tolerance extremes are given. A general formula for the yield, which is applicable to any arbitrary statistical distribution, is presented. An illustrative example for verifying the formulae is given. Karafin's bandpass filter has been used for applying the yield formula for a number of different statistical distributions. Uniformly distributed parameters between tolerance extremes, uniformly distributed parameters with accurate components removed and normally distributed parameters were considered. Comparisons with Monte Carlo analysis were made to contrast efficiency.
Explicit expression for the characteristic function of generalized legendre filters
Authors: Rakovich B. D. , Popovich M. V. 
Published: July 2007

AbstractThe explicit formula for the characteristic function of all‐pole lowpass filters with monotonic passband magnitude response is derived. It is shown that the characteristic function of Legendre, Halpern, LSM and other known classes of monotonic magnitude all‐pole filters that are synthesized from the magnitude squared function, can be obtained by assigning different values to a variable parameter in the general expression obtained. The approximation method consists of using a weighted least‐mean‐square norm to minimize the area under the first derivative of the characteristic function.
Optimum realizations of single‐amplifier networks with zero pole frequency sensitivity and with minimized pole‐Q deviation
Authors: Singh N. P. , Ramachandran V. , Bhattacharyya B. B. 
Published: July 2007

AbstractThis paper discusses realizations of second‐order open‐circuit voltage transfer functions by single‐amplifier active RC networks. These realizations are based on the polynomial decompositions having the property that the sensitivity of ω0 with respect to the amplifier gain is zero. In addition, the gain‐sensitivity product of Q is minimized and the element spread is contained to be within acceptable limits. The realizations are suitable for hybrid IC technology.
A fast and reliable computer program for the accurate hurwitz factorization of a polynomial
Authors: Eckelmann Gerd 
Published: July 2007

AbstractA method is explained for the decomposition of an even polynomial into the product of a Hurwitz polynomial and an Anti‐Hurwitz polynomial. This problem arises, for instance, in network synthesis. A computer program is presented and its application is explained. Several examples show the properties of the proposed method.