bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Properties of Vinylogous 6‐(Cyclopentadienyl)pentafulvenes
Authors: Eiermann Matthias , Stowasser Bernd , Hafner Klaus , Bierwirth Klaus , Frank Anette , Lerch Alexander , Reußwig Jürgen
Published: July 2007

The application of the principle of kinetic stabilization on vinylogous 6‐(cyclopentadienyl)pentafulvenes 1 led to the synthesis of the di‐ and tetra‐tert‐butyl derivatives 7a – e and 8a ‐ c. Their reactions with bases and acids form charged, heteroatom‐free cyanine‐type carbanionic 9a ‐ e, 10a – e and carbocationic ll a – e, 12a – c species which were characterized with NMR and UV/Vis spectroscopy. Conclusions on the ion pair structures of the alkali metal salts 9a ‐ e and 10a – c are drawn from the spectroscopic data. Additionally, in one case the behavior of the alkali metal salt 10b towards oxidants was studied by cyclic voltammetry and the structure of the corresponding hydrocarbon 8b was proved by X‐ray structural analysis.
Notizen / Notes. Probing Diazonium Ion ‐ Crown Ether Molecular Complexes bv Tandem Mass Spectrometry (FAB‐MS/MS) Acid‐Base Chemistry Within a Cluster
Authors: Laali Khosrow
Published: July 2007

The molecular complexes (cluster ions) formed between various aromatic diazonium ion salts ArN2⊕BF4⊖ and 18‐crown‐6 host molecules are studied by FAB mass spectrometry. The nature of the interaction is probed by MS‐MS experiments in which the ArNF (crown) 1:1 complexes are mass‐selected and subjected to collisionally activated dissociation (CAD), using helium as collision gas. The results suggest that acid‐base chemistry (proton and hydride transfer) occurs within the guest ‐host complex. Precedented mechanistic pathways for ArN2⊖ dediazoniation in the condensed phase are used as guidelines to explain these observations.
Synthesis and Reactivity of Functionalized Dimethylsilyl Complexes of the Formula (η5‐C5H5)Re(NO)(PPh3)(SiMe2X); New Base‐Stabilized Silylene Complexes, Novel Lewis Acid Adducts, and Evidence for Base‐Free Silylene Complexes
Authors: Lee Kenneth E. , Arif Atta M. , Gladysz John A.
Published: July 2007

Reactions of (η5‐C5H5)Re(NO)(PPh3)(SiMe2H) (1) and CHCl3, CBr4, and CHI3 give halosilyl complexes (η5‐C5H5)Re(NO)‐(PPh3)(SiMe2X) [X = Cl (2), Br (3), I (4); 66–84%]. Addition of Me3SiOTf to 2 gives triflate (η5‐C5H5)Re(NO)(PPh3)(SiMe2OTf) (5; 97%), which in turn reacts with (Me2N)3S⊕ [SiMe3F2]⊖ to give (η5‐C5H5)Re(NO)(PPh3)(SiMe2F) (6; 77%). Reaction of 5 and pyridine gives the base‐stabilized silylene complex [(η5‐C5H5)Re(NO)(PPh3){SiMe2(NC5H5)}]⊕ TfO⊖ (7; 84%). CH2Cl2 solutions of (η5‐C5H5)Re(NO)(PPh3)(CH3) (8) or 2 and Lewis acids are studied by IR and NMR. As assayed by IR, 8/ECl3 solutions (E = B, Al) show ReNO–ECl3 (major) and Re–ECl3 (minor) adducts. Solutions of 2/BCl3 show analogous adducts (‐78°C), and in the presence of excess BCl3 (η5‐C5H5)Re‐(NO–BCl3)(PPh3)(SiMe2Cl) (11) crystallizes. Solutions of 2/AlCl3 show uncomplexed 2 and Re–AlCl3 (major) and ReNO–AlCl3 (minor) adducts. In contrast to 2–7 and 2/BCl3, 1H‐ and 13C‐NMR spectra of 2/AlCl3 suggest an equilibrium with the base‐free silylene complex [(η5‐C5H5)Re(NO)(PPh3)‐( = SiMe2)]⊕ X⊖.
Makrocyclisch modifizierte Verbindungen vom TTF‐ und TCNQ‐Typ
Authors: Vögtle Fritz , Alfter Frank , Steckhan Eberhard , Mavili Semra , Nieger Martin
Published: July 2007

Molecules of the TTF and TCNQ Type with Macrocyclic Skeletons

The electron‐rich and electron‐poor macrocycles 1 – 3 have been synthesized. Their [1.1](3,3′)biphenylophane framework is formed by Kharasch reaction. Whereas in the well‐known donors and acceptors I–III the functionalities are conjugated, in their macrocyclic “analogues” 1–3 the conjugation is prevented by the meta‐connection of the phenylene rings. The redox properties —studied by cyclovoltammetry — are discussed. The X‐ray analysis of 3 shows considerable deviations from a planar structure.
(Butadien)(cyclopentadienyl)niob‐Komplexe
Authors: Herberich Gerhard E. , Englert Ulli , Linn Klaus , Roos Peter , Runsink Jan
Published: July 2007

(Butadiene)(cyclopentadienyl)niobium Complexes

The known bis(butadiene)(cyclopentadienyl)niobium complex (C5H4R)Nb(C4H6)2 (1, RH) exists in solution as a 1 : 1 mixture of a bis(cis‐butadiene) isomer 1a and a (cis‐butadiene)(trans‐butadiene) isomer 1b. In solution the barrier to isomerisation is 80 ± 2 kJ/mol. New derivatives 2 (RMe) and 3 (RSiMe3) of 1 are described. One of the butadiene ligands in 1 – 3 is readily substituted with CO, CNtBu, P(OMe)3, and PMe3. CpNb(PMe3)2(C4H6) (7) reacts with disubstituted acetylenes to form acetylene complexes CpNb(PMe3)(C4H6)(RCCR') (8: R, R'=Ph, 9: RMe, R'=Ph, and 10: RPh, R'=SiMe3), The structure of 9 resembles that of bent metallocene derivatives with the acetylene acting as a 2‐e ligand.
(Benzol)osmium(II)‐Komplexe mit cyclischen Oxycarben‐ und Vinylether‐Liganden
Authors: Werner Helmut , Knaup Wolfgang , Schulz Michael
Published: July 2007

(Benzene)osmium(II) Complexes with Cyclic Oxycarbenes and Vinyl Ethers as Ligands

The compounds [C6H6Os(PR3)]2] (5, 6) react with 1‐alkynols HCCCH2CHR'OH in the presence of AgPF6 to give cyclic oxycarbene complexes (7–9) in almost quantitative yields. During the reaction vinylideneosmium intermediates are probably formed. Deprotonation of 7–9 with NaH affords the vinyl ether complexes (10 – 12). Reaction of 10 with methyl triflate (in the presence of NaH) leads to the formation of (13). The crystal and molecular structure of the oxycarbene complex 7 has been determined.
Gold Complexes with Selenium Ligands, IV(1) Preparation, Crystal Structures and Reactions of Phosphine(selenourea)gold(I) Complexes
Authors: Jones Peter G. , Thöne Carsten
Published: July 2007

(Triphenylphosphine)(selenourea)gold(I) chloride [Ph3PAuSeC‐ (NH2)2]+ Cl‐ (1) and the corresponding dppm derivative dppm[AuSeC(NH2)2]22+ 2l‐ (2) are prepared from SeC‐ (NH2)2 and the appropriate chloro(phosphine)gold(I) complex. The reaction between 1 and aqueous Na2CO3 leads to the neutral complex μ‐selenido{bis[(triphenylphosphine)gold(I)]} (Ph3PAu)2Se (3). An analogous reaction with 2 leads to a dark red oil, which has not yet been characterized. The reaction between 3, Ph3PAuCl, and AgSbF6 leads to the ionic complex [(Ph3PAu)3Se]+SbF6‐ (4) in good yield. X‐ray structure analyses of 1,2, and 3 confirm the expected linear geometry at the gold atom and reveal short intramolecular Au – Au contacts for 2 and 3. Short nonbonding distances between the nitrogen atoms of the amino groups and the chloride ions in the crystal structures of 1 and 2 probably indicate hydrogen bonds.
Synthese der Si‐funktionellen Acetylsilarie tBu(Me3SiCH2)[MeC(O)]SiF und tBu(Me3SiCH2)[MeC(O)]SiH sowie Synthese und Kristallstruktur des Acetylsilanols tBu(Me3SiCH2)[MeC(O)]SiOH: Substrate für mikrobielle Reduktionen
Authors: Tacke Reinhold , Hengelsberg Heidi , Klingner Etta , Henke Henning
Published: July 2007

Synthesis of the Si‐Functional Acetylsilanes tBu(Me3SiCH2)[MeC(O)]SiF and tBu(Me3SiCH2)[MeC(O)]SiH as well as Synthesis and Crystal Structure of the Acetylsilanol tBu(Me3SiCH2)[MeC(O)]SiOH: Substrates for Microbial Reductions

The racemic Si‐functional acetylsilanes tBu(Me3SiCH2)[MeC(O)]SiF (1) and tBu(Me3SiCH2)[MeC(O)]SiH (2) and the racemic acetylsilanol tBu(Me3SiCH2)[MeC(O)]SiOH (3) were synthesized from Si(OMe)4 (4) as substrates for microbial reductions [4 → tBuSi(OMe)3 (5) → tBu(Me3SiCH2)Si(OMe)2 (6) → tBu(Me3SiCH2)SiF2 (7) → tBu(Me3SiCH2)[CH2 = C(OMe)]SiF (8) → 1; 8 → tBu(Me3SiCH2)[CH2 = C(OMe)]SiH (9) → 2; 6 → tBu(Me3SiCH2)[CH2 = C(OMe)]SiOMe (10) → 3]. Compounds 1–3 were found to be reduced by cells of Trigonopsis variabilis (DSM 70714) [≡ SiC(O)Me → ≡ SiCH(OH)Me]. The crystal and molecular structure of 3 was studied by singlecrystal X‐ray diffraction. In the crystal, racemic 3 forms infinite chains built up by intermolecular OH…O bonds between the hydroxyl and acetyl groups of molecules of the same absolute configuration.
Synthesis and molecular structure of tin(IV) 1‐pyrrolecarbodithioates
Authors: Seth Neena , Gupta Vishnu D. , Nöth Heinrich , Thomann Martina
Published: July 2007

The 1‐pyrrolecarbodithioate complexes of tin, PhSnCl(S2CNC4H4)2 (1) and Sn(S2CNC4H4)4 (2) have been synthesized and characterized by IR and NMR spectra (1H, 13C and 119Sn). δ119Sn suggests hexacoordination for 1 and an even higher coordination number for 2. X‐ray structure determinations of these as well as of Me2Sn(S2CNC4H4)2 (3) have shown that 3 is one of the few known examples with a skew‐trapezoidal bipyramidal configuration. 1 attains approximately a cis‐octahedral geometry with two bidentate carbodithioate ligands with the Cl atom and the phenyl group in cis position. Complex 2 possesses two bidentate ligands while the other two are essentially anisobidentate leading to a structure between an octahedraon and a dodecahedron.
Synthesen, Strukturen und thermische Abbaureaktionen von TlI‐, PbII‐ und SeII‐Komplexen mit 2,2‐Dicyanethylen‐1,1‐diselenolat
Authors: Hummel Hans‐Ulrich , Fischer Edmund , Fischer Thomas , Gruß Ditmar , Franke Andrea , Dietzsch Wolfgang
Published: July 2007

Preparation, Structures, and Thermal Decomposition Reactions of Complexes Consisting of TlI, PbII, and SeII and 2,2‐Dicyanoethylene‐1,1‐diselenolate

The 2,2‐dicyanoethylene‐1,1‐diselenolate‐containing compounds (AsPh4)2[Tl2(Se2C=C(CN)2)2], (AsPh4)2[Pb(Se2C=C‐(CN)2)2], and (NBu4)2[Se(Se2C=C(CN)2)2] have been prepared and characterized by single‐crystal structure analysis. The molecular structures of the complex anions 1–3 are significantly influenced by the presence of stereochemically active lone pairs. 1 is dimeric with an Se4Tl2 octahedral centre with a Tl–Tl distance of 3.547(4) Å and an average Tl–Se bond length of 3.143(4) Å. In 2 Pb constitutes the centre of a distorted pseudo‐trigonal bipyramid PbSe4E [Pb–Seave = 2.948(3) Å] with one equatorial position obviously occupied by the lonepair E. In 3 the ligands are coordinated to the central Se, which is situated in a centre of symmetry, in an undistorted way giving rise to a Ψ‐octahedral SeSe4E2 geometry [Se–Seave = 2.617(2) Å]. The compounds (AsPh4)2 · 1, (AsPh4)2 · 2 and (NBu4)2 · 3 have been decomposed thermally to yield TlSe, PbSe as well as Se. The observed contamination of TlSe and PbSe with As is avoided by using (NBu4)2 · 1 and (NBu4)2 · 2 as precursor materials.
Konkave Farbstoffe mit Azobenzol‐Einheiten als Chromophore, Photoschaltelemente und hohlraumbildende Bausteine
Authors: Bauer Martin , Vögtle Fritz
Published: July 2007

Concave Dyes with Azobenzene Units as Chromophores, Photoswitchable and Cavity‐Forming Elements

Five monomacrocyclic (12a–e) and three types of threefold azobenzene‐bridged oligomacrocyclic compounds (15, 17, 28, 31) have been synthesized. Due to the cavity‐forming chromophores at the periphery of these molecules they represent concave dyes. The watersoluble monocycles 12b–e were photoisomerized and investigated before and after E/Z isomerization with regard to their host properties for small neutral organic guest compounds. The bicyclic azobenzene derivative 31 with triphenylethane spacers exhibits in/out isomerism. The in/out isomer 31c was separated by HPLC from 31a and b, which are in equilibrium at room temperature. The tris(2‐aminoethyl)amine‐capped Schiff bases 15 and 17 form complexes with Cu(CH3CN)4BF4.
1,2‐Dihydro‐1,3,2λ5,4λ5‐diazadiphosphet – Synthese, Struktur und Isomerisierung zum „inneren Salz”︁ von 1,3,2,4λ5‐Diazadiphosphetan‐2‐iumhydroxid*
Authors: Böske Jürgen , Niecke Edgar , Krebs Bernt , Läge Mechtild , Henkel Gerald
Published: July 2007

1,2‐Dihydro‐1,3,2λ5,4λ5‐diazadiphosphete – Synthesis, Structure and Isomerization to the „Inner Salt”︁ of 1,3,2,4λ5‐Diazadiphosphetan‐2‐ium Hydroxide

The photochemical reaction of the azidophosphane (iPr2N)2PN3 (1) with the tetraazaphospholene (3) and the bis(imino)phosphorane (Me3Si)2NP(NSiMe3)2 (6) proceeds by elimination of N2 to yield (5) and by 1,3‐silyl group shift to furnish (8) the structures of which were determined by means of NMR data and, in the case of 5, additionally by X‐ray structure analysis.
Donorsubstituierte Cyclobutenyliden–Komplexe und Cyclobutenone aus Vinyliden–Komplexen und elektronenreichen Alkinen
Authors: Fischer Helmut , Podschadly Oliver , Früh Angelika , Troll Carsten , Stumpf Rüdiger , Schlageter Andreas
Published: July 2007

Donor–Substituted Cyclobutenylidene Complexes and Cyclobutenones from Vinylidene Complexes and Electron–Rich Alkynes

Pentacarbonyl(vinylidene) complexes of chromium and tungsten, (CO)5MCC(R1)R2 (1) [MW: R1R2Ph (a), R1  tBu, R2Et (b), Me (c); MCr: R1tBu, R2Me (d)] react with 1‐(diethylamino)‐1–propyne by regiospecific addition of the CC bond of the alkyne to the CαCβ bond of the vinylidene ligand to form the cyclobutenylidene complexes 2a–d. Oxidative cleavage of the cyclobutenylidene ligand from 2a–d gives the corresponding cyclobutenones. The reactions of 1b with bis(diethylamino)acetylene and of 1a with 1–ethoxy–1‐propyne afford the cyclobutenylidene complexes 3b and 4a, respectively. In contrast, 1a reacts with diorganylcyanamides, NCNR2 (RMe, Et, iPr), by ligand displacement and formation of tetraphenylbutatriene and diorganyl–cyanamide complexes. The structures of 2c and 4a were established by X–ray analyses.
Oxidation of Trimethylsilene with Molecular Oxygen — a Matrix Isolation Study
Authors: Sander Wolfram , Trommer Martin
Published: July 2007

The thermal oxidation of 1,1,2–trimethylsilene (1) has been investigated in O2‐doped argon matrices. The oxidation proceeds rapidly at temperatures below 40 K, and two principal oxidation products have been identified as dimethylvinylsilyl hydroperoxide (6) and dimethylvinyloxysilanol (7). The mechanism leading to these products is discussed.
Synthese und Struktur von Hexakis(trimethylsilyloxy)triarsazen
Authors: Baier Michael , Bissinger Peter , Schmidbaur Hubert
Published: July 2007

Synthesis and Structure of Hexakis(trimethylsilyloxy)triarsazene

Hexakis(trimethylsilyloxy)triarsa(V)azene [(Me3SiO)2AsN]3 (1) has been prepared from arsenic acid H3AsO4 and hexamethyldisilazane (Me3Si)2NH. According to an X‐ray crystal‐structure determination 1 features a slightly puckered six‐membered As3N3 ring. The formation of 1 proceeds with evolution of ammonia via tris(trimethylsilyl)orthoarsenate (Me3SiO)3AsO (2) as an intermediate, which could be isolated as a by‐product. The reaction of 2 with hexamethyldisilazane also gives 1 in high yields. The influence of temperature, solvent and concentration of reactants on product formation has been investigated, and side reactions are discussed.
Enantioselektive Katalyse, IX. Neue optisch reine 3,4‐Bis(phosphanyl)pyrrolidine mit Phenyl‐und Anisylgruppen sowie deren Palladium‐und Rhodiumkomplexe
Authors: Nagel Ulrich , Krink Thomas
Published: July 2007

Enantioselective Catalysis, IX[1]. – New Optically Pure 3,4‐Bis(phosphanyl)pyrrolidines with Phenyl and Anisyl Groups Including Their Palladium and Rhodium Complexes

Methods for the synthesis of the diastereomeric mixture of the [P(R,S),3R,4R,P′(R,S)]1‐1‐(tert1‐butoxycarbonyl)1‐3,4‐bis[(2‐methoxyphenyl)phenylphosphanyl]pyrrolidines (2a, b, c) are described. For the chromatographic separation and purification of the ligand diastereomers we transformed them into the PdI21‐complexes (10a, b, c). The structure of (PR,3R,4R,P′R)1‐1‐(tert1‐butoxycarbonyl)1‐3,4‐bis[(2‐methoxyphenyl)phenylphosphanyl]pyrrolidine‐P,P′}diiodopalladium (10 b) was determined by X‐ray diffraction. Treatment of the palladium complexes with KCN yielded the pure phosphanes. The rhodium complexes (11a, 11b, 11c), which can be used as catalysts in enantioselective hydrogenations, were obtained by reaction of [Rh(COD)2]BF4 with compound 2a, 2b, or 2c.
Repetitive‐Synthesis of Bulky Dendrimers – A Reversibly Photoactive Dendrimer with Six Azobenzene Side Chains
Authors: Mekelburger Hans‐Bernhard , Vögtle Fritz , Rissanen Kari
Published: July 2007

Dendrimers with bulky repeating units containing up to 43 benzene rings (in 9) have been obtained by using a repetitive divergent synthetic strategy (three generations). The new functional dendrimer 13 containing six azobenzene units at the periphery was synthesized allowing a reversible switching of the shape and size of the molecule upon irradiation. An X‐ray structure analysis of the dendritic molecule 3a shows the inclusion of acetonitrile.
Penta‐und Hexabrombullvalene
Authors: Rebsamen Karl , Schröder Gerhard
Published: July 2007

Penta‐and Hexabromobullvalenes

The Pentabromobullvalenes 2a–d and the hexabromobullvalenes 3a/b are synthesized and the corresponding isomers are identified. 2 constitutes an equilibrium of four isomers. The isomer 2a is separated from the mixture by column chromatography. For the kinetically most stable isomer 2a the half‐life time for equilibration at 55°C amounts to ca. 30 h. Two non‐equilibrating isomers 3a and 3b are isolated, however, in the case of hexabromobullvalene 3. The bullvalene‐typical property of a fluxional structure is now practically no longer existent.
Diastereo‐ und enantioselektive Synthese 1,2‐trans‐substituierter Cycloalkancarbonsäureester und Sulfone durch Michael‐initiierte Cyclisierungen via SAMP‐/RAMP‐Hydrazone[1,2]
Authors: Enders Dieter , Scherer Hermann J. , Runsink Jan
Published: July 2007

Diastereo‐ and Enantioselective Synthesis of 1,2‐trans‐substituted Cycloalkanecarboxylates and Sulfones by Michael‐Initiated Cyclisation via SAMP / RAMP Hydrazones[1,2]

An efficient and flexible synthesis of 1,2‐trans‐substituted cycloalkanecarboxylates and sulfones of high diastereo‐ and enantiomeric purity is described. The key step of the procedure is a Michael‐initiated ring closure (MIRC) reaction employing the SAMP/RAMP hydrazone method. Depending on the chain length of the ω‐bromo(iodo)enoates 2, 3 and the type of ketone SAMP‐hydrazone 1, 3‐, 5‐, 6‐ and 7‐membered cycloalkane‐carboxylates 4–7 or cyclopentanesulfones 24 bearing two or three stereogenic centers are formed with very high asymmetric induction. In the same manner, MIRC reactions with ω‐(ethoxycarbonyl)enoate 26 give rise to 3‐substituted cyclopentanone‐2‐carboxylates 27, but with lower overall chemical yields. The relative and absolute configurations are based on X‐ray structure analyses, spectroscopic and mechanistic investigations.
Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 36. (E)‐1,1,1,4,4,4‐Hexakis(trimethylsilyl)‐2‐buten [(H3C)3Si]3C—HCCH—C[Si(CH3)3]3 und Bis[tris(trimethylsilyl)silyl]ethin [(H3C)3Si]3Si—C≡C—Si[Si(CH3)3]3
Authors: Bock Hans , Meuret Jochen , Schödel Holger
Published: July 2007

Structures and Molecular Properties of Sterically Overcrowded Molecules, 36[1]. — (E)‐1,1,1,4,4,4‐Hexakis(trimethylsilyl)‐2‐butene [(H3C)3Si]3C—HCCH—C[Si(CH3)3]3 and Bis[tris(trimethylsilyl)silyl]ethin [(H3C)3Si]3Si—C≡C—Si[Si(CH3)3]3

The single crystal structure of an ethylene derivative, in which the two substituent half‐shells are separated by a CC spacer of about 403 pm length, shows C≡C distances of 404, 415 as well as 421 pm between non‐adjacent and of 352 pm between adjacent methyl groups, i.e. close to or within their van der Waals radii sum of 400 pm. The PE‐spectroscopically determined vertical first ionization energies of both compounds, 7.78 eV and 7.71 eV, are each the lowest ones reported so far for disubstituted ethylenes and acetylenes. Despite of irreversible cyclovoltammetric oxidation potentials, the radical cation of the six‐fold R3Si‐substituted 2‐butene can be generated by SbCl5/H2CCl2 and characterized below 230 K by its ESR spectrum.
Solvatochromism of Sterically Hindered Stilbazolium Betaines and Its Relationship to Reichardt's ET(30) Scale: The Problem of the Measurement of the Polarity vs the Acidity of Alcohols
Authors: Catalán Javier , Pérez Pilar , Elguero JosÉ , Meutermans Wim
Published: July 2007

The hydrogen bond acidity of twenty primary, secondary, and tertiary alkanols has been measured by the solvatochromic method by using three stilbazolium betaines: stilbazolium betaine itself (SB), o‐tert‐butyl‐substituted (TBSB), and o,o'‐di‐tert‐butyl‐substituted SB (DTBSB). The spectral differences between two of these betaines and in particular the Δ' values which correspond to SB and DTBSB, have been compared with Reichardt's ET(30) values. Excluding sterically hindered alcohols, both scales are linearly related. For normal alkanols, the Δ' values have been compared with the absorbance of the stretching of the OH band both free and associated with N,N‐dimethylacetamide (DMA). There is a linear relationship between Δ' and ln [(Av(OH)associated)/(Av(OH)free)] which proves that Δ' is a measure of the hydrogen‐bond donor (HBD) acidity of alcohols. Contrary to some expectations, the effect of alkyl substituents shows a slow attenuation with increasing number of carbon atoms in the chain.
Stereoselectivity of the Thermally Initiated Free‐Radical Chain Addition of Cyclohexane to 1‐Alkynes
Authors: Metzger JüRgen O. , Blumenstein Michael
Published: July 2007

Alkanes can be added to alkynes in a thermally initiated free‐radical chain reaction (“ane reaction”). The addition of cyclohexane to 1‐alkynes 1a–1 yields a mixture of (Z)‐ and (E)‐2‐cyclohexyl‐1‐alkenes 3a–1. An essential step in this reaction is the addition of cyclohexyl radicals to the alkynes to give 2‐cyclohexyl‐1‐alkenyl radicals 2a–1 which abstract hydrogen from cyclohexane to yield the products 3a–1. The stereoselectivity of the addition has been measured in the temperature range of 160–260°C. It strongly depends on the substituent X of the radical center and varies over a range of almost four orders of magnitude from [(Z)‐3a]:[(E)‐3a] = 33 (X = OMe) at 160°C to [(Z)‐31]:[(E)‐31] = 0.012 (X = tBu) at 260°C. The stereoselectivity is further influenced by the temperature and in most cases by the concentration of the hydrogen donor cyclohexane. The reaction is discussed in terms of the stereoselectivity of the addition of cyclohexyl radicals to the alkyne, of the structure of the 1‐alkenyl radical (σ and π radical, respectively), the rate of inversion in the case of σ alkenyl radicals, and the relative rates of syn and anti hydrogen transfer.
Zinkkomplexe von Aminosäuren und Peptiden, 2[1]. Koordination einfacher Histidin‐Derivate an Zink
Authors: Förster Martin , Burth Rainer , Powell Anne K. , Eiche Thomas , Vahrenkamp Heinrich
Published: July 2007

Zinc Complexes of Amino Acids and Peptides, 2[1]. – Coordination of Simple Histidine Derivatives to Zinc

The bis(L‐histidine)ZnCl2 complex 1 is likely to have tetrahedral ZnN2Cl2 coordination. For the compound (L‐histidine)‐ZnCl2 · HCl (2) a structure determination has revealed a tetrahedral ZnOCl3 coordination. Of the C‐protected histidine derivatives His‐OMe and His‐NH2 and zinc salts of non‐coordinating anions the complexes (His‐OMe)2ZnX2 (3) and (His‐NH2)2Zn(ClO4)2 (4) were obtained. A structure determination of (His‐OMe)2Zn(BPh4)2 · H2O has revealed a ZnN4 coordination with chelating histidine units. Of the N‐protected histidine derivative Nα‐acetylhistidine the complexes (Ac‐His)ZnX · H2O (5, X = ClO4, BF4) have been isolated which are coordination polymers in the solid state. From pH‐dependent 13C‐NMR studies it is concluced that in solution the imidazole N and carboxyl O are coordinated to zinc in (Ac‐His)Zn and (Ac‐His)2Zn units. The doubly protected histidine derivative Bz‐His‐OMe acts as a monodentate ligand forming the tetrahedral complexes (Bz‐His‐OMe)4Zn(ClO4)2 (6) and [(Bz‐His‐OMe)2Zn(2,9‐dimethyl‐o‐phenanthroline)](ClO4)2 (7).
Kleine Ringe, 78. Tri‐tert‐butyl(trimethylsilyl)cyclobutadien und Tri‐tert‐butyl(trimethylsilyl)tetrahedran
Authors: Maier Günther , Born Dieter , Bauer Ines , Wolf Reinhard , Boese Roland , Cremer Dieter
Published: July 2007

Small Rings, 78[1]. ‐ Tri‐tert‐butyl(trimethylsilyl)cyclobutadiene and Tri‐tert‐butyl(trimethylsilyl)tetrahedrane

The chemistry of diazo(1,2,3‐tri‐tert‐butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse. Upon irradiation it fragments exclusively into the acetylenes 7 and 8. Flash thermolysis, on the other hand, gives — aside from the two acetylenes — tri‐tert‐butylazete (10) and trimethylsilyl cyanide (11). Upon heating 6 presumably isomerizes via betaine 17 to Dewar‐diazabenzene 13 — which is split into 10 and 11 — and diazabenzvalene 18. This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16, — The CuCl‐catalyzed thermal decomposition again follows a different route. Under these conditions tri‐tert‐butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex. Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated. Upon irradiation of 5 a quantitative isomerization to tri‐tert‐butyl(trimethylsilyl)tetrahedrane (29) occurs. This second, spectroscopically unequivocally confirmed tetrahedrane melts at 179°C. In solution the isomerization to cyclobutadiene 5 starts at about 160°C. That means, it is thermally even more stable than tetra‐tert‐butyltetrahedrane.
{Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2‐ethen)nickel(0) und verwandte Verbindungen, Teil II
Authors: Pluta Christian , Pörschke Klaus‐R. , Gabor Barbara , Mynott Richard
Published: July 2007

{Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2‐ethene)nickel(0) and Related Compounds, Part II

The coordinatively unsaturated (16e) (ethene)nickel(0) stannylene complex (C2H4)2Ni=Sn{CH(SiMe3)2}2 (1) reacts with 1,6‐heptadiene with preservation of the Ni=Sn bond to yield quantitatively the 1,6‐diene derivative (η2,η2‐C7H12)Ni=Sn‐{CH(SiMe3)2}2 (2). The alkene ligands of both 1 and 2 are readily displaceable. Compounds 1 and 2 react with butadiene at −50°C by a 4‐e oxidation of the metal‐metal pair Ni(0)/Sn(II) to Ni(II)/Sn(IV) and concomitant reduction of two butadiene molecules to butenediyl moieties to afford stereo‐selectively the 16‐e complex Ni‐cis‐{η3(Ni),η1(Sn)‐anti‐C3H4CH2}2Sn{CH(SiMe3)2}2 (3). Similarly, the reaction of 1 or 2 with isoprene yields regio‐ and stereoselectively the derivative Ni‐cis‐{η3(Ni,η1(Sn)‐anti‐C3(3‐Me)H3CH2}2Sn{CH‐(SiMe3)2}2 (4). These reactions imply the cleavage of one formal NiSn bond and the formation of two new SnC bonds. Upon reaction of 3 with PMe3 the configuration of the allyl system changes and, again fully stereoselectively, the 18‐e addition compound (Me3P)Ni‐cis‐{η3(Ni),η1(Sn)‐syn‐C3H4‐CH2}2Sn{CH(SiMe3)2}2 (5) is formed. When 5 is treated with BPh3, the phosphane ligand is trapped and, kinetically controlled, Ni‐cis‐{η3(Ni),η1(Sn)‐syn‐C3H4CH2}2Sn{CH(SiMe3)2}2 (6) is obtained as a stereoisomer of 3. At 40°C 6 slowly rearranges into the thermodynamically stable stereoisomer Ni‐trans‐{η3(Ni),η1(Sn)‐syn‐C3H4CH2}2Sn{CH(SiMe3)2}2 (7). Mild protolysis of 3 with pyridine hydrochloride or hydrobromide affords region and stereoselectively (Me3Si)2CH}2(X)SnNi‐(η3‐1‐MeC3H4)(NC5H5) (X = C1, 8a; Br, 8b). In the course of this protonation reaction one butadiene molecule is eliminated, accompanied by a 2‐e reduction of the metal‐metal pair Ni(II)/Sn(IV) to Ni(II)/Sn(II) and, at the expense of two SnC bonds, reformation of a NiSn bond. All compounds are isolated in high yield and fully characterized by 1H‐, 13C‐, and 31P‐NMR spectroscopy.
Synthese, Deprotonierung und Ringerweiterung eines 2,3‐Diboratetralins
Authors: Weinmann Wolfgang , Pritzkow Hans , Siebert Walter
Published: July 2007

Synthesis, Deprotonation, and Ring Expansion of a 2,3‐Diboratetralin

Herrn Prof. Dr. Helmut Werner zum 60. Geburtstag gewidmet.

Reaction of K2[1,2‐C6H4(CH2)2] with [Cl(Me2N)B]2 leads to 2,3‐bis(dimethylamino)‐2,3‐diboratetralin (4a) in 58% yield. Deprotonation of 4a with lithium 2,2,6,6‐tetramethylpiperi‐dide yields the crystalline dilithium salt 6a. Insertion of 3‐hexyne into the BB bond of 4a results in the formation of 2,5‐bis(dimethylamino)‐3,4‐diethyl‐1,2,5,6‐tetrahydro‐2,5‐benzodiborocine (7a) in 38% yield. The constitutions of 4a, 6a, and 7a were derived from 1H‐, 11B‐, 13C‐NMR, and MS data and proven for 6a and 7a by X‐ray,structure analyses.
Hohervalente Derivate der d‐Metall‐Sauren, 13. Homoscorpionate als tripodale Ankerliganden chlorfunktioneller Oxo‐ und Imidokomplexe von Elementen der 5.‐7. Gruppe
Authors: Sundermeyer Jörg , Putterlik Jürgen , Foth Margarete , Field John S. , Ramesar Niyum
Published: July 2007

Higher‐Valent Derivatives of the d‐Metal Acids, 13. — Homoscorpionates as Tripodal Anchoring Ligands of Chloro Functionalized Oxo and Imido Complexes of Elements of Group 5–7

Hydridotris(pyrazolyl)borate complexes of elements of group 5–7 have been prepared by reaction of d0‐metalloyl chlorides [M(Y)nClm]x (Y = O, NR) with KTp* (Tp* = κ3‐HB(3,5‐Me2pz)3). Thus [NbOCl3]x and [TaOCl3]x are converted into monomeric and well‐characterized oxo complexes [Tp* Nb(O)Cl2] (1) and [Tp*Ta(O)Cl2] (2). In a similar way [Tp* Mo(O)2Cl] (3) and [Tp*W(O)2Cl] (4) have been obtained from the oxo chlorides [MoO2Cl2]x and [WO2Cl2]x, respectively. tert‐Butylamine reacts with NbCl5 and TaCl5 in the presence of pyridine to give the imido pyridine complexes [Nb(NtBu)Cl3(py)2] (5) and [Ta(NtBu)Cl3(py)2] (6) in excellent yield. Imido complexes [Tp*V(NtBu)Cl2] (7), [Tp* Nb(NtBu)Cl2] (8), and [Tp*Ta(NtBu)Cl2] (9) are formed by the reaction of KTp* with the precursers [V(NtBu)Cl3]x or 5 and 6, respectively. The corresponding imido complexes of group 6, namely [Tp*Cr(NtBu)2Cl] (10), [Tp*Mo(NtBu)2Cl] (11), and [Tp*W(NR)2Cl] (R = tBu 12a, 2,4,6‐Mesityl 12b, SO2Ph 12c) are obtained directly from the imidoyl chlorides or their complexes with Lewis bases. 11 and 12 are prone to protonation at the imido ligand to yield cationic amido species [Tp*M(NtBu)(NHtBu)Cl]BF4 (M = Mo 13, W 14). Finally the preparation of cationic imido rhenium complex [Tp*Re(NtBu)2Cl]PF6 (15), isoelectronic with 10–12, is described. The molecular structure of 11 has been determined by X‐ray diffraction. Despite of a maximum electron count of 20 valence electrons, all three pyrazolyl groups of the tripodal ligand are facially coordinated. In a way similar to the well‐known ring slippage of analogous cyclopentadienyl complexes, the weakest bound pyrazolyl ligand is asymmetrically attached to molybdenum deviating from the positions expected for local C3v symmetry.
Transition Metal Chemistry of Main Group Hydrazides, 9. Platinum Complexes of Diphosphanylhydrazides R2PN(Me)N(Me)PR2 · PtCl2 (R = OPh, o‐OC6H4CH2CHCH2)
Authors: Sreenivasa Reddy V. , Katti Kattesh V. , Barnes Charles L.
Published: July 2007

While the transition metal complexes of bis(phosphanyl)amines (PII‐N‐PIII) have been known for over three decades, the ligating properties of the next homologue PIII‐N‐N‐PIII have been unprecedented so far. The X‐ray structures of cycloplatinaphosphanehydrazides, [(OR)2PN(Me)N(Me)P(OR)2‐PtCl2], reveal short distances for the P‐N [1.639(5) Å] bonds.
Transanular Interactions in Difunctional Medium Rings, 6. Spectroscopic Investigations of Bicyclic Amino Ketones
Authors: Wiesmann Reinhard F. , Rademacher Paul
Published: July 2007

The endo‐7‐(aminomethyl)bicyclo[3.3.1]nonan‐3‐ones 1–4 with a primary, secondary, or tertiary amino group have been synthesized, and their tendency to form the corresponding tricyclic amino carbinols has been investigated by theoretical (MMX, AM1) and experimental (PE, 13C‐NMR spectroscopy) methods. Comparison of the characteristic spectroscopic properties of 1–4 with those of the isochromophoric monofunctional compounds 7–11 indicates that 1 and 2 form mixtures with the tricyclic isomers 5 and 6, respectively, whereas 3 and 4 show no interactions between the amino and the carbonyl group in the solely present bicyclic structures.
Novel, Very Strong, Uncharged Auxiliary Bases; Design and Synthesis of Monomeric and Polymer‐Bound Triaminoiminophosphorane Bases of Broadly Varied Steric Demand
Authors: Schwesinger Reinhard , Willaredt Jürgen , Schlemper Helmut , Keller Manfred , Schmitt Dieter , Fritz Hans
Published: July 2007

The synthesis and properties of a number of very strong iminophosphorane bases up to an extremely high level of steric hindrance are described. They cover a range of ca. 4 pK units in basicity and a range of more than 11 orders of magnitude in their rates of methylation with methyl iodide. Most of the systems are readily prepared in up to molar quantities, conveniently recovered from their salts and are of high chemical and thermal stability. Crystal structures were determined in order to parametrize a force field, which is utilized in molecular modeling studies offering a rationalization of the observed differences in steric hindrance and basicity. Depending on the degree of steric protection of the basic center, these novel bases are proposed as unprecedented, versatile auxiliary bases in E2 eliminations and in reactions involving deprotonation in the presence of more or less strong electrophiles.
New Organophosphorus Ligands: Cyclopropanation and Other Reactions of Cumulenes Bearing Diphenylphosphanyl Substituents
Authors: Manhart Stefan , Schier Annette , Paul Martin , Riede Jürgen , Schmidbaur Hubert
Published: July 2007

Hydrophosphorylation of 1,4‐bis(diphenylphosphanyl)butadiyne with diphenylphosphane leads to the butadiene (Ph2P)2CCHCHC(PPh2)2 (1). Treatment of 1 with dimethylsulfonium methylide gives the vinylcyclopropane (Ph2P)2CCHCH(CH2)C(PPh2)2 (2). Compound 2 reacts with aqueous hydrogen peroxide, elemental sulfur, or selenium to afford the tetrachalcogenides (Ph2XP)2CCHCH(CH2)C(PXPh2)2 with X = O (3), X = S (4), X = Se (5), respectively. While the tetraphosphane 1 and the vinyl‐cyclopropane compound 2 cannot be converted into a bis‐(cyclopropyl) compound with an excess of Me2SCH2, the tetrasulfide 4 readily affords a mixture of (1R,1′R)‐/(1S,1′S)‐and meso‐2,2,2′,2′‐tetrakis(diphenylthiophosphinyl)‐1,1′‐bicyclopropyl (6, 7) in good yield. Treatment of 1,1,4,4‐tetrakis‐(diphenylphosphanyl)butatriene with dimethylsulfonium methylide leads to the vinylidenecyclopropane (Ph2P)2CCC(CH2)C(PPh2)2 (8). Compound 8 is converted into its tetrasulfide (Ph2SP)2CCC(CH2)C(PSPh2)2 (9) by treatment with elemental sulfur. The crystal structures of 1, 2, 4, 7, and 8 have been determined by single‐crystal X‐ray diffraction.
Palladium‐Copper‐Catalyzed Coupling of Tricarbonylchromium‐Complexed Phenylacetylene with Iodoarenes – A Facile Access to Alkynyl‐Bridged Cr(CO)3‐Complexed Benzenes
Authors: Müller Thomas J. J. , Lindner Hans Jörg
Published: July 2007

The palladium‐copper‐catalyzed coupling of the tricarbonyl‐chromium‐complexed chlorobenzene 1 with (trimethylsilyl)‐acetylene gives tricarbonyl{η6‐[(trimethylsilyl)ethynyl]‐benzene}chromium(0) (2) in high yield. After desilylation of 2 tricarbonyl[η6‐(ethynylbenzene)]chromium(0) (3) is obtained quantitatively. Using the palladium‐copper‐catalyzed methodology, we can readily introduce Cr(CO)3‐complexed phenylethynyl units by a multifold coupling of 3 with iodobenzene, 1,2‐, 1,3‐, 1,4‐di‐ and 1,3,5‐tiiodobenzene (4a–e) or 1 to give polynuclear Cr(CO)3‐complexed (phenylethynyl)benzenes 5a–e and doubly Cr(CO)3‐complexed tolane 6 in good to moderate yield. The crystal structure analyses of μ3‐{η6:η6:η6[1,3,5‐benzenetriyltris(2,1‐ethynediyl)]tris(benzene)}tris[tricarbonylchromium(0)] (5e) and μ‐{η6:η6‐[1,2‐ethynediylbis(benzene)]}bis[tricarbonylchromium(0)] (6) reveal that the tricarbonylchromium tripods in the same molecule are arranged in antiparallel syn‐eclipsed conformations. The Eglington coupling of 3 affords a doubly Cr(CO)3‐complexed diphenylbutadiyne 7 in excellent yield.
Enantioselective Catalysis, XII. Synthesis of Bis(phosphane) Palladium and Rhodium Complexes on a Polyethylene Oxide Grafted Polystyrene Matrix (TentaGel) and the Catalytic Behavior of the Rhodium Complexes
Authors: Nagel Ulrich , Leipold Joachim
Published: July 2007

A new polymer‐attached rhodium catalyst on a polyethylene oxide‐grafted styrene matrix (TentaGel) is described. The corresponding anchor molecules were prepared by starting from different Boc‐protected chiral pyrrolidinebis(phosphane)Pd complexes. The crystal structure of [3R,4R)‐N‐(4‐carboxybutanoyl)‐3,4‐bis(diphenylphosphanyl)pyrrolidine‐P,P′]‐diiodopalladium (1c) was determined. The formation of an amide bond between TentaGel and anchor molecules resulted in polymer‐bound Pd bisphosphane complexes. De‐complexation of the Pd with cyanide and reaction of the free polymeric ligand with [Rh(COD)2]BF4 led to the active hydrogenation catalyst. The influence of different solvents on the swelling volume and the catalytic behavior was tested. The polymer‐bound rhodium complex [(3R,4R)‐N‐(1,5‐dioxo‐5‐TentaGel‐amino‐pentyl)‐3,4‐bis (diphenylphosphanyl)pyrrolidineP,P′] (1,5‐cyclooctadiene)rhodium tetrafluoroborate (7) has about the same catalytic activity and enantioselectivity as the homogeneous complex [(3R,4R)‐N‐(tert‐butoxycarbonyl)‐3,4‐bis(diphenylphosphanyl)pyrrolidine‐P,P′] (1,5‐cyclooctadiene)rhodium tetrafluoroborate (9) in the same solvent mixture. It is possible to reuse 7 once, then it abruptly loses activity. This behavior remains to be clarified.
Euler characteristics of algebraic varieties
Authors: Cappell Sylvain E. , Maxim Laurentiu G. , Shaneson Julius L.
Published: July 2007

This note studies the behavior of Euler characteristics and of intersection homology Euler characteristics under proper morphisms of algebraic (respectively, analytic) varieties. The methods also yield, for algebraic (respectively, analytic) varieties, formulae comparing these two kinds of Euler characteristics. The main results are direct consequences of the calculus of constructible functions and Grothendieck groups of constructible sheaves. Similar formulae for Hodge‐theoretic invariants of algebraic varieties under morphisms were announced by the first and third authors in [5, 14]. © 2007 Wiley Periodicals, Inc.
Synthesis of a useful class of transmission line networks
Authors: Valtonen Martti
Published: June 2007

A general class of networks consisting of cascaded commensurate transmission lines and shunt imaginary conductances is considered. This kind of network performs an excellent approximation to transmission line networks with shunt stubs or lumped elements. The realizability conditions for the driving‐point admittance and transfer function have been given in a previous paper. The imaginary conductances were generated by introducing an extra phase angle into the scattering function. In the present paper two alternative methods are given

by identifying in different ways the roots of the numerator polynomial in the input scattering function.

by using non‐symmetric gain functions.

The influence of different factorizations and non‐symmetric gain functions upon the element values variation is examined.
Network analysis of strongly coupled transverse apertures in waveguide
Authors: Rozzi T. E.
Published: June 2007

Methods of field and network theory are jointly applied to the problem of transverse aperture‐type discontinuities in cascade under the conditions of multimodal excitation and interaction. A space Fourier transformation (modal analysis) translates the field problem into a network problem, whereby discontinuities take the significance of Hilbert‐ports à la Zemanian. When a discontinuity is considered as enclosed by an ideal cavity, representing energy storage in the ‘localized’ modes, Foster's form of the reactance matrix of the discontinuity is recovered. The relationship with the variational method in computing the resonance matrix of the ‘accessible’ modes is illustrated. Green's function of cascaded apertures is obtained by finite network analysis. A few examples of thick interacting inductive irises in cascade are numerically investigated. Results show very good agreement with experiment.
Application of an extended maximum modulus principle to minimum‐energy‐storage multiresistor realizations of an impedance
Authors: Smith William E.
Published: June 2007

It is shown by direct appeal to the analytic properties of current transfer functions, that minimum energy storage by a passive linear network implies that the current transfer to each resistor of the realization is a constant fraction of the corresponding single minimum‐phase‐shift transfer function of Darlington synthesis. The demonstration makes use of an extended version of the maximum modulus principle.
Efficient computation of large change multiparameter sensitivity
Authors: Singhal K. , Vlach J. , Bryant P. R.
Published: June 2007

In many applications, a network has to be solved repeatedly while certain element values are changed. The computation is reduced significantly if the network functions are generated in terms of these variable parameters explicitly. This paper presents a method of doing this which requires the solution of the network with at most m+1 excitations when there are m variable parameters.
On the solvability of DC equations and the implicit integration formula
Authors: Roska Tamás , Klimó János
Published: June 2007

The paper contains the following new results concerning the solvability of the DC equations and the implicit integration formula of a broad class of nonlinear networks.

A new method of proof is given.

Conditions are given for checking the unique solvability of the DC equation F(x)+Ax = b in case of monotone (not strictly monotone) and ‘steep’ characteristics and in the case when the characteristics have negative slope. Furthermore existence theorems are given under very weak conditions.

In the case of a broad class of nonlinear networks sufficient conditions are presented for the unique solvability of the implicit integration formula when the characteristics are monotone or have negative slope.

Some practical consequences of the theorems are also discussed.
Two active rc configurations for realizing nonminimum phase transfer functions
Authors: Soliman Ahmed M.
Published: June 2007

Two different realizations are given for synthesizing a second order nonminimum phase transfer function. The first circuit uses a single operational amplifier and a passive RC bandpass building block and has the advantage of being always stable. The second configuration uses two operational amplifiers to activate a symmetrical twin T, and has the advantage of providing a unity gain factor. Sensitivities to all circuit components and the frequency limitation equations for both networks are given.
Gain‐phase analysis of digital filters with applications
Authors: Haykin Simon S.
Published: June 2007

The article includes two fundamental sets of relations for minimum phase digital filters; the one set defines the relations between the gain and phase components, and the other set defines the relations between the group delay and gain slope components of the pulse transfer function of the filter. Two applications of these relations are considered: (i) Graphical computation of the phase characteristic of a digital filter with a prescribed gain characteristic. (ii) Computation of the gain characteristic of a linear phase digital filter.
An active rc filter for pcm systems
Authors: Gensel Joachim , Meissner Rolf , Seidel Volkmar
Published: June 2007

An active RC low‐pass filter using two high‐gain amplifiers with bridge feedback is described which serves as terminating unit of a PCM system channel. Some conditions derived from telecommunication applications and effecting the choice of the filter structure are discussed in detail, and the principles guaranteeing imaginary zeros under the condition of absolute stability of the filter sections are explained. The measurement results confirm that, using the method described, the fairly severe requirements, particularly the high pass‐band constancy demanded for units of telecommunication equipments, can be met at an economical cost.
Reciprocity, inter‐reciprocity, and transposition in wave digital filters
Authors: Fettweis Alfred
Published: June 2007

For wave digital filters, basic theorems which, although being more general, have a similarity to the difference form of Tellegen's theorem for classical networks, are derived, and the properties of reciprocity and inter‐reciprocity are defined. To each wave digital filter, there corresponds an entire family of transposed wave digital filters; each of these is inter‐reciprocal with the original one.

Two types of transposition, called intrinsic and elementary transposition, are of particular importance. For these, the number of multipliers is the same after transposition as before, which is of interest for obtaining equivalent realizations. Intrinsic and elementary transposition are related to transposition (in the classical sense) and duality in the reference filter from which the wave digital filter is derived.
New general approach to commensurate tem transmission line networks using state space techniques
Authors: Kittel Ludwig
Published: June 2007

The paper begins with an investigation of the scattering properties of commensurate TEM transmission line networks, and emphasis is placed upon the distinction between normal networks and general (including non‐normal) networks.

It is then shown that the state space concept of linear discrete systems is applicable to these networks. This provides a general and powerful systemtheoretical method for determining the network behaviour in the time and frequency domains. The waves on the transmission line elements are chosen as state variables; and for the important technical case of normal networks it is shown that each transmission line element contributes one state variable only. The entries in the state space matrices are formed by the scattering parameters of the connections and endings of the line elements; and the general method of obtaining these matrices is explained by detailed examples.

An automatic network analysis program based on the state space approach needs only matrix multiplications. The program works primarily in the time domain, and the frequency behaviour is then computed by Fast Fourier Transform. The advantages of the program are demonstrated by a typical example.

Finally an application to digital filters imitating TEM transmission line networks is presented.
Single‐tuned solid‐state microwave oscillators
Authors: Kenyon N. D.
Published: June 2007

The incorporation of a lossy stabilizing element into a microwave oscillator circuit is described. Such an element facilitates the application of dc bias to the circuit, and makes it unlikely that oscillations occur at undesired frequencies. There follows a description of configurations that have been used for solid‐state oscillators at frequencies from 8 GHz to over 110 GHz. These circuits have two outstanding features which facilitate characterization both of the circuits themselves and of diodes mounted therein.
Analysis of nonlinear model for operational amplifiers in active RC networks
Authors: Forsén Anders , Kristiansson Lars
Published: June 2007

In active RC networks certain nonlinear phenomena may occur due to the nonlinear properties of the amplifiers. It is shown that one of these, the slew rate limitation, may give rise to the jump phenomenon. The class of networks to be studied are described by a third order nonlinear differential equation. The theoretical and experimental results are found to correspond well.
Reciprocity in lumped linear‐time‐varying circuits
Authors: Howson D. P.
Published: June 2007

Reciprocity conditions applicable to LLTV circuits are considered. The sensitivity of some of these to time‐zero changes, and to LLTI network embedding is shown. Generalization from element to network is discussed and demonstrated to be sometimes possible. An equivalent circuit for a LLTV element is devised to show the essential non‐reciprocity of the general case.