bluuebunny/crossref_metadata_2025 huggingface dataset:
N2Hx Coordination at the Tripod‐Cobalt Template CH3C(CH2PPh2)3Co: the Transformation of η2‐HNNMe2 into η1‐NNMe2Ligands
Authors: Körner Volkmar , Huttner Gottfried , Vogel Sabine , Barth Annette , Zsolnai Laszlo
Published: July 2007

While η2‐coordination of N2H4 and N2H3‐ to tripod‐cobalt entities has been reported, stabilization of N2H2 in this system has not yet been achieved. It is observed that [tripodCo(η2‐HNNMe2)]+ (3) is transformed into [tripodCo(η1‐NNMe2)]+ (4) by reaction with LiN(TMS)2 as a base. The deprotonation of 3 is accompanied by a redox reaction, and the overall reaction corresponds to the transformation of 3 to 4 with the loss of an electron and a proton. The observed coupling of deprotonation and oxidation is just the reverse of the processes assumed to occur during nitrogen fixation. The results are established by the usual analytical and spectroscopic techniques as well as by X‐ray analyses.
Reactions of Complex Ligands, LXXIIIntermolecular Pauson‐Khand Reactions of Ethyl 2‐Phenylethynylcyclopropanecarboxylates and [Amino(trans‐2‐phenylethynylcyclopropyl)methylidene]pentacarbonylchromium(0)
Authors: Kretschik Oliver , Heinz Dötz Karl , Nieger Martin
Published: July 2007

The intermolecular Pauson‐Khand reactions of ethyl trans‐2‐phenylethynylcyclopropanecarboxylate (1t) and [amino‐(trans‐2‐phenylethynylcyclopropyt)methylidene]pentacarbonylchromium (9) with norbornane lead to ester and metal carbene functionalized exo‐tricyclodecenones 3b–6 and 13–16, respectively, in moderate to high yields. The incorporation of the alkyne is moderately regioselective but less diastereoselective. Pairs of diastereomers are isolated after column chromatography, which can subsequently be separated by recrystallization. The minor diastereomer 3 and the major diastereomer 15 are characterized by X‐ray structure analysis.
Highly Substituted Cyclams: Stereoselective Synthesis and Coordination Properties
Authors: König Burkhard , Pelka Mario , Möller Oliver , Dix Ina , Jones Peter G.
Published: July 2007

We report here a new synthetic route to highly‐substituted tetraazamacrocycles. Raney nickel hydrogenation of macrocyclic phenylenediamine–acetylacetone condensation products gives cyclams in high yield with complexes all‐cis stereoselectivity. The extensive C‐substitution of the cyclam 2a changes its ligand properties markedly. The X‐ray structure analyses of NiII, CuII, and ZnII complexes of 2a reveals a deviation of the metal ion coordination geometry from the usual square‐planar arrangement. This may account for the differences in the redox properties of the NiII and CuII complexes of 2a leads to more positive oxidation and reduction potentials compared to the analogous unsubstituted cyclam complexes. While the binding constant between Zn(ClO4)2 and 2a is lower by a factor of 105 compared to cyclam, the subsequent binding of uridine to the zinc‐cyclam complexes in methanol/water is slightly stronger in the case of 2a · Zn(ClO4)2].
Inter‐ and Intramolecular Thermal Activation of Aliphatic C–H Bonds Mediated by Complexes Containing the Fragments [{Cy2P(CH2)nPCy2}M] (n=1–4, M = Rh, Ru)
Authors: Leitner Walter , Six Christian
Published: July 2007

A well defined geometrical structure and a well established catalytic potential for a plethora of processes puts the chelate rings [{R2P<(CH2)nPR2}M] (M = Rh, Ru) among the most interesting candidates for catalytic alkane functionalization in homogeneous solution. It is demonstrated that intermolecular thermal C–H activation (3→4) is possible with readily accessible complexes [{Cy2P(CH2)nPCy2}Rh(hfacac)] (n = 1–4, 1a–c and [Cy2P(CH2)nPCy2}Ru(η3‐C4H7)2] (n = 1–3, 2a–c) containing such fragments. A maximum of 5 catalytic cycles was achieved with complex 2a. In case of Ru complexes containing the same ligands with n =3 and 4, intramolecular cleavage of three adjacent C–H bonds in one of the cyclohexyl substituents at phosphorus also occurs readily leading to formation of a new polydentate k2P,P', η3‐allyl ligand.
Halfsandwich‐Type Triisopropylstibane Ruthenium Complexes with 16‐, 17‐, and 18‐Electron Configurations and an Unsymmetrical Binuclear 18/16‐Electron Ru2(SbiPr3) Species
Authors: Braun Thomas , Laubender Matthias , Gevert Olaf , Werner Helmut
Published: July 2007

The paramagnetic ruthenium complex [(η5‐C5Me5)RuCl2‐{SbiPr3}] (2), which is prepared from [(η5‐C5Me5)RuCl2]n (1) and SbiPr3, reacts with Mg/Hg in THF to give the coordinatively unsaturated 16‐electron species (η5‐C5Me5)RuCl)(SbiPr3)] (3). Compound 3 is obtained in much better yield from [(η5‐C5Me5)Ru(μ3‐Cl)]4 (4) and SbiPr3 (molar ration 1:4). While 3 reacts with CO to give the 18‐electron complex [(η5‐C5Me5)RuCl(CO)(SbiPr3)] (5), on treatment of 3 with HCˇO2Me the metallacycle [(η5‐C5Me5)RuCl{k2(C,C)‐C(CO2Me}=CHC(CO2Me)=CH}(SbiPr3)] (6) is obtained. The reaction of 4 with SbiPr3 in the molar ratio of 1:2 affords the binuclear compound [(η5‐C5Me5)(SbiPr3)Ru(μ‐Cl)2Ru(‐C5Me5)] (7). The molecular structures of 2 and 7 have been determined by X‐ray crystallography.
Iminoacylcobalt Compounds as Starting Materials for the Synthesis of Alkynylcobalt Halfsandwiches and Cobaltaheterocycles
Authors: Werner Helmut , Xiaolan Liu , Peters Karl , von Schnering Hans Georg
Published: July 2007

The iminoacylcobalt compound [C5H5Co(C(CH3)=NCH3)(PMe2Ph)] (3) reacts with propargylic acid ester HC=CCO2R (R = Me, Et) to give the alkynylcobalt halfsandwich‐type complexes [C5H5Co(C(CH3)=NHCH3)(C=CCO2R)‐(PMe2Ph)]I (5, 6). With HC=CCO2Me as the substrate, besides 6 (R = Me) the five‐membered cobaltaheterocycle [C5H5Co{K2(N, C)‐N(CH3)C(CH3)CHC(CO2Me)}(PMe2Ph)]I (7) is also obtained. The reactions of 3 and the analogous benzyl derivative 4 with terminal alkynes HC=CR' (R' = CH2OH, CMe2OH, [CH2]2OH, CH2OMe, H, Me, nBu, Ph) afford exclusively the heterocyclic complexes [C5H5Co(K2(N,C)‐N(R)C(CH3CHCR')(PMe2Ph)]I (R = CH3, CH2Ph) (8–18) in 60–70% yield. The molecular structures of 5 (R = Et) and 16 (R = Me, R' = Ph) have been determined by X‐ray crystallography.
C–H Bond Activation of Simple Alkenes with (C5H5)CO Fragments: Preparation, Molecular Structure, and Dynamical Behaviour of Tri‐ and Tetranuclear Cyclopentadienylcobalt Cluster complexes with μ‐Cycloalkyne Ligands
Authors: Wadepohl Hubert , Borchert Till , Pritzkow Hans
Published: July 2007

Vicinal C–H bonds of the cycloalkenes CnH2n (n = 5–8) were activated upon treatment under mild conditions with reactive sources of the (C5H5)CO fragment. With [C5H5)CO(C2H4)2] (2a), the trinuclear cluster complexes [H2((C5H5)CO)3(μ3‐C2(CH2)n‐2)] (5a: n = 5; 5c: n = 5d: n = 8) were formed. Using the more reactive [(C5H5)2Co]/K, 5a–5dwere obtained, along with small amounts of the tetranuclear [{(C5H5)CO}4r{μ4‐C2(CH2)n‐2}] (8a–c: n = 5–7). X‐ray structure analyses of 5c, d and 8b, c were performed. A μ‐‖ (orμ3‐η1:η2:η1) coordination of the cycloalkyne ligands was found in the trinuclear cluster complexes. The tetranuclear 8b, c had the cycloalkynes quadruply bridging (μ4‐η1:η2:η2:η1_ a butterfly arrangement of the metal atoms. The acetylenic carbon–carbon bonds are considerably lengthened upon coordination [1.392(4), 1.398(3) å in 5c d; 1.464(8), 1.499(5) Å in 8b, c]. Three dynamic processes – alkyne “walk” on top of the CO3 triangle, μ2‐hydride migration, and μ2/μ3‐hydride exchange – are operational in the trinuclear 5a–d. Dynamic NMR data for 5a are consistent with a “windshield‐wiper” mechanism for the alkyne migration. Hydride exchange is associated with a higher energy barrier, and is probably and independent dynamic process.
On the Protonation of Fluoro Cryptands and the Possibility of CF…HN+ Hydrogen Bonds
Authors: Plenio Herbert , Diodone Ralph
Published: July 2007

The protonation of several fluoro cryptands synthesized from 1,3‐bis(bromomethyl)−2‐fluorobenzene and diaza‐macrocycles (diaza‐12‐crown‐4, diaza‐15‐crown‐5, diaza‐18‐crown‐6 and 2,3‐benzodiaza‐15‐crown‐5) has been investigated by 1H‐, 13C‐ and 19F‐NMR spectroscopy, X‐ray crystal structure analysis and IR spectroscopy, with a view to detecting possible CF…HN hydrogen bonding. From the crystal structures of mono‐ and diprotonated 23‐fluoro‐4,7,20‐trioxa‐1,10‐diazatricyclo[8,7,5,112,16]tricosa‐12,14,16(23)‐triene (FN2O3·H+ and FN2O3·2H+) it is apparent that protonation leads to a shortening of the non‐bonded nitrogen‐fluorine and nitrogen‐oxygen distances and consequently to O·HN hydrogen bonds. A related type of interaction involving fluorine appears possible since short N(H)…F distances (281.2–286.6 pm) with NHF angles between 130–140° are observed. A Cambridge Structural Database search was performed and 27 structures with short CF…HN contacts were found. On the other hand, IR spectra do not give any clear evidence in favor of CF…HN hydrogen bonding since the N–H vibrations in FN2O3…H+ and FN2O3…2H+ as well as in FN2O4…2H+ do not experience longwave shifts relative to the N–H vibrations of the reference systems HN2O3·H+, HN2O3…2H+ and HN2O4…2H+.HN2O3 and HN2O4 are almost identical to FN2O3 and HN2O4, respectively, the only difference being that the single fluorine atom of the fluoro cryptands is replaced by hydrogen. NMR spectroscopic evidence concerning CF…HN interactions is ambiguous: (i) A spin‐coupling between 1H and 19F (NH…F) is observed. (ii) The 1JCF value is reduced by up to 15 Hz upon protonation of the fluoro cryptand. (iii) An NMR competition experiment between FN2O3 and HN2O3 yields no evidence for an increased basicity of the fluoro cryptand. Finally, it can be stated that evidence in favor of CF…HN hydrogen bonds is inconclusive; should such an interaction exist it will certainly be very weak.
Gold Coordination by 2‐(Diphenylphosphanyl)aniline
Authors: López‐De‐Luzuriaga José M. , Schier Annette , Schmidbaur Hubert
Published: July 2007

The reaction of 2‐(diphenylphosphanyl)aniline (1) with (tetrahydrothiophene)gold(I) chloride in the molar ratio 1:1 gives a stable molecular complex 2, in which the gold atom is bonded to the phosphorus atom. Reaction of two equivalents of ligand 1 with one equivalent of the salt [(tht)2Au]ClO4 results in the displacement of both thioether ligands, affording the ionic complex {[(2‐NH2C6H4)PPh2]2Au}+ ClO−4 (3a), in which the metal center is exclusively P‐coordinated. Treatment of [(tht)2Au]ClO4 with ligand 1 (1:1) affords the mixed P/S‐coordinated complex 4, the structure of which has been confirmed by single‐crystal X‐ray diffraction. The reaction of ligand 1 with [(Ph3P)Au]+ BF−4 leads to a mixture of products which are components of an equilibrium between the unsymmetrical salt {[(2‐NH2C6H4)PPh2]Au(PPh3)} BF−4 with the two symmetrical species 3b (the BF−4 analogue of 3a) and [(Ph3P)2Au]+ BF−4, With {[(Ph3P)Au]3O}+ BF−4 as the aurating agent, the ligand 1 (molar ratio 1:1) is converted into a polynuclear complex 7, which is tentatively assigned a structure with intimate aggregation of six gold atoms.
Diastereoselective Synthesis of Tricarbonyl(thiophene)chromium Complexes
Authors: Ganter Christian , Brassat Lutz , Ganter Beate
Published: July 2007

2,3‐Disubstituted 2‐hydroxyalkylthiophenes 9 and 10 were synthesized in a five‐step sequence and their diastereoselective complexation with the Cr(CO)3 fragment leading to the corresponding tricarbonyl(thiophene)chromium complexes 11 and 12 was investigated. The diastereoselectivity achieved in the complexation reaction was up to 85% d. e. and depends primarily on the bulkiness of the substituent in the 3‐position of the thiophene. The relative configuration of the stereogenic center and the planar element of chirality of complex 11a was determined by X‐ray diffraction analysis.
Monomeric Phosphanylgalanes — Synthesis and Structural Characterization
Authors: Linti Gerad , Köstler Wolfgand , Frey Ronald , Schwenk Holger
Published: July 2007

The monomeric phosphanylgallanes R2GaPR'R (R = tmp, Mes; R' = H, tBu; R' Mes, tBu), the diphosphanylgallane mesGa(PtBu2)2, and diphosphandiylbisgallane [tmp2GaP‐(tBu)]2, have been synthesized from alkali metal phosphides and substituted gallium chlorides. Low‐temperature NMR studies of the phosphanylgallanes reveal no barrier to rotation about the gallium‐phosphorus bond. Analysis of the crystal structures of tmp2GaPtBu2 confirms the monomeric nature of these molecules. The gallium‐phosphorus bond lengths are found to be 237.5, 233.5, 235.4 pm (averaged), and 242.3 pm, respectively, with all phosphorus atoms being pyramidally coordinated.
Divalent Tin and Lead Compounds EX2 Acting as Bridging Ligands in [{(CO)5M}2EX2]2− (E  Sn, Pb; M  Cr, Mo, W): Preparation and Properties
Authors: Kircher Peter , Huttner Gottfried , Schiemenz Berthold , Heinze Katja , Zsolnai Laszlo , Walter Olaf , Jacobi Albrecht , Driess Alexander
Published: July 2007

The reaction of Na2[M2(CO) 10] (M = Cr, Mo, W) with SnHal2 (Hal = Cl, Br) is a well established procedure for the synthesis of anions of type A, [{(CO)5M)SnHal3]−. Conditions are described which, for the same type of procedure, result in the additional formation of dianions of type B, [{(CO)5M}2SnHal2]2−. Procedures for separating these two types of anions in the form of their stable [Ph4P]+ or [nBu4N]+ salts by appropriate salt metathesis are presented. The structures of theses species have been characterized by X‐ray analysis of three salts containing type A anions and two salts containing type B anions. The reactivity of the type B salts containing the bulky cations [Ph4P]+ or [nBu4N]+, respectively, is remarkably low; the salts are, however, transformed into highly reactive sodium salts by further metathesis with Na[BPh4]. In such salts the halide substitutents are easily exchanged as shown by the synthesis of ]})CO(5Cr}2oxinato]− (4)− from [Na‐(THF)x]2[{(CO)5Cr}2SnCl2] and sodium 8‐oxoquinolate, Na[C9H6NO]. The structure of the anion, 4 is compared to the structure of [[(CO)5Cr)SnCl2· THF] and sodium 8‐oxochinolate. The preparation of the dinuclear anions [{(CO)5Cr}2E(OOCCH3)2]2− (E  Sn, 2g; E  Pb, 3) is accomplished by the reaction of [Ph4P]2[Cr2(CO)10] with the corresponding acetates E(OOCCH3)2. While 2g and 3 are formal analogues of the type‐B anions, their structures reveal an asymmetrical η2‐coordination of the two acetato ligands, in each case ending up in a 4+2 coordination for the main group centres, instead of the four‐coordination observed for [{(CO)5M}2SnHal2]2−, All compounds have been characterized by usual spetroscopic and analytical techniques. X‐ray analyses have been performed for selected examples. 119Sn‐NMR data are presented for all of the compounds which contain tin‐centred ligands.
Thermal Reactions of 5‐Alkylidene‐4,5‐dihydro‐3H‐1,2,4(λ3)‐diazaphospholes (4‐Phosphapyrazolines) – A Route to Various PHeterocycles and to 2‐Phosphabutadienes
Authors: Manz Berthold , Bergsträßer Uwe , Kerth Jochen , Maas Gerhard
Published: July 2007

The 5‐alkylidene‐4,5‐dihydro‐3H‐1,2,4(λ3)‐diazaphospholes (4‐phosphapyrazolines) are thermally much more stable than related compounds without the exocyclic double bond. Thermolysis reactions typically occur in the range 110‐150°C in toluene solution, and different, mostly competing, reaction pathways are observed. Thermal extrusion of nitrogen from 8a‐g gives rise to β‐phosphanaylsiloxyalkenes 10, benzo[c]‐phosphole derivatives 11, 14 and 115, (β‐siloxyalkylidene)‐Phosphiranes 12, and dihydro‐1,3‐oxaphospholes 13. The thermolysis of 5‐alkylidene‐4,5‐dihydro‐4‐trimethylsilyl‐3‐trimethylsilyloxy‐3H‐1,2,4‐dizaphospholes 17 afforded three products, including the highly substituted and stable 2‐phosphabutadienes 18 formed by nitrogen extrusion and rearrangement. Finally, the 4‐chloro‐3‐trimethylsilyloxy‐substituted heterocycle 21 was transformed at 170°C into 4H‐1,2,4‐diazaphosphole 23. The structures of 13c and 18a were determined by single‐crystal X‐ray diffraction.
Synthesis and Molecular Structure of a Rhenium Complex Derived from 8a‐Amino‐6‐methyl‐ergoline
Authors: Spies Hartmut , Noll Bernhard , Noll Steffi , Johannsen Bernd , Findeisen Matthias , Leibnitz Peter , Schulze Paul E.
Published: July 2007

Current research in radiopharmaceutical chemistry is aimed at the design of technetium‐based receptor‐binding radiotracers because of the excellent nuclide properties of the isotope 99mTc. Tc tracers and the corresponding complexes of rhenium, as the inactive surrogate of Tc, are required to imitate organic agonists or antagonists of the receptor. We have started studies with ergolines, which are known to be dopamine substitutes. The present report deals with the functionalization of 8α‐amino‐6‐methyl‐ergoline (2) with a 2‐mercaptoacetyl group, and the subsequent synthesis of the first rhenium complex containing a pendent ergoline moiety [Re‐ O(SSS)(RS)] (HSSSH = HS‐CH2CH2‐S‐CH2CH2‐SH and RSH = 8a‐amino‐N‐(2‐mercaptoacetyl)‐6‐methyl‐ergoline) (4). The molecular structure of the rhenium complex was determined by X‐ray crystal structure analysis.
The Chemistry of Metallacyclic Alkenylcarbene Complexes, 8 Chelated Allyl‐Ironcarbene Complexes with a Centrally Tethered π‐Ligand‐Synthesis and Reactions with Nucleophiles
Authors: Förtsch Walter , Hampel Frank , Schobert Rainer
Published: July 2007

The title complexes 8 and 9 are easily prepared in two or three steps from iron carbonyls and isobutene diol 5 by Meerwein alkylation of the intermediate acyl complexes 6 and 7. With carbon and heteroatom nucleophiles like enolates and triphenylphosphane they form either stable 4‐substituted alkene‐carbene complexes 10 and 11, or substituted trimethylenemethane tricarbonyliron complexes like 12. Oxidation with H2O2/NaOH both of the alkene‐carbene complexes 11 and of the less stable β‐oxo‐substituted trimethylene‐methane complexes 13, as obtained from reaction of 8 with lithium enolates, yields the corresponding substituted allyl carbamates 15 or the allyl alcohols 14, which are formally bis‐ and monosubstituted derivatives, respectively, of the starting isobutene diol.
Nickel(II) Complexes of Chiral Tripodal N,O,S‐Ligands: Square‐Planar vs. pseudo‐Octahedral Coordination in the Solid State and in Solution, Metal‐Induced Racemization of the Ligand
Authors: Berkessel Albrecht , Seidel Lutz , Bats Jan W. , Bolte Michael , Neumann Thomas
Published: July 2007

The complexation behavior of three chiral, tripodal N,O,S‐ligands with nickel(II) salts was examined. It was found that the coordination mode of the ligands (bidentate N,O and N,S; tridentate N,O,S) and of the central nickel ion (square‐planar vs. pseudo‐octahedral) is not simply an intrinsic property of the ligand‐metal combination, but also a function of the counter ions and of the solvent of crystallization. In the case of one ligand, a diamagnetic square‐planar and a paramagnetic pseudo‐octahedral form could be switched back and forth, by just changing the solvent of crystallization from methanol to ethanol. By using an enantiomerically pure tripodal N,O,S‐ligand, a metal induced racemization was unveiled which would have otherwise remained undetected.
Organoantimony Oxides: Preparation and Crystal Structures of [(2‐PhOC6H4)O (C6H4)2Sb]2O2 and (o‐Tol2Sb)4O6
Authors: Breunig Hans Joachim , Probst Joachim , Ebert Klaus Heinz , Lork Enno , Cea‐Okuvares Raymundo , Alvarado‐Rodriguez José‐Guadalupe
Published: July 2007

Air oxidation of (Oxydi‐2,1‐phenylene)(2‐phenoxyphenyl)stibane (1) gives the phenoxystibane oxide [(2‐PhOC6H4)O(C6H4)2Sb]2O2 (2). Single crystals of (o‐Tol2Sb)4− O4(O2)2 (3) were obtained by air oxidation of o‐TolSb‐(SiMe3)2. Crystal structures of 2 and 3 are reported.
The Coordination Chemistry of Fluorocarbons: Group‐I and Group‐ II Metal Ion Complexes of Fluoro Macrocycles
Authors: Plenio Herbert , Diodone Ralph
Published: July 2007

Two new fluoro macrocycles BenzoFN2O3 and F(N2O2)2C2H4 were synthesized in the reactions of 1,3‐bis(bromomethyl)‐2‐fluorobenzene with benzo‐diaza‐15‐crown‐5 and 1,2‐bis(diaza‐12‐crown‐4)ethane, respectively, in 30% yield each. Close CF...metal ion interactions in the respective alkaline metal complexes in solution are evidenced by characteristic shifts of the 19F‐NMR resonances of up to δ = 18.7 relative to the free ligand and by a decrease of the 1J(CF) coupling constant of up to 20 Hz, which is most pronounced in BenzoFN2O3 · Li+ and F(N2O2)2C2H4 · K+. In BenzoFN2O3· Li+ a1J(19F‐7Li) of 15.5 Hz was observed, which is indicative very close CF...Li+ interactions in solution. In the X‐ray crystal structures of BenzoFN2O3 · Na+ [CF ⃛Na+ 246.8(2) pm], 26‐fluoro‐4,7,13,16‐tetraoxa‐1, 10‐diazatricyclo[ 8.8.7.1 20,24 ] ‐ hexacosa‐20,22,24(26)triene · Na+ (CF ⃛Na+ 267.1(2) pm) and 21 ‐fluoro‐3,6,9,12,15,18‐hexaoxabicyclo[ 18.3.1 1,20]heneicosa‐ l(24),20,22‐triene. Ba2+ [CF ⃛Ba2+ 299.0(3) pm] short CF ⃛metal interactions were found. Such close CF ⃛metal ion interactions do not result in a lengthening of the C‐F bonds, which is not a sign of weak CF ⃛metal ion interactions, since a Cambridge Structural Database search revealed that a shortening of the C‐O bond length is also not observed in crown ether complexes of alkaline metals.
Donor Complexes of Silylene, Germylene, and Stannylene
Authors: Schoeller Wolfgang W. , Schneider Ralf
Published: July 2007

The complexes of various donor molecules, AH3 (A = N, P, As, Sb, Bi) and AH2 (A = 0, S, Se, Te) with silylene, germylene, and stannylene (1Al ground state) were studied by means of quantum chemical investigations at ab initio level utilizing all valence electron basis sets and relativistic corrected effective core potential methods. Accordingly, the donor molecules are weakly bound, the association energies are in the range of 15–30 kcal per mole. The exothermic energies for adduct formation, i.e., the resulting binding energies for the donor complexes, decrease in the order silylene > germylene > stannylene. The population analysis indicates for NH3 and BiH3 only a weak bonding towards the XH2 fragment (X =Si, Ge, Sn) while the higher homologues (A = P, As, Sb) form ylide structures, 1.2‐dipolaric in nature. The addition of two donor molecules has been studied for silylene and is much less favourable than donor mono‐addition. For the donor mono‐addition a dual parameter relationship between (a) the HOMO energies of the donor (n‐orbital of the AH3 unit, n, p‐orbitals for AH2) and (b) the covalent bond energies (from the literature) versus the binding energies of the donor‐acceptor compounds was examined. This dual parameter equation describes satisfactorily the essential features of the stabilities of the donor‐acceptor structures.
Synthesis and Structures of Sodium Phenylhydrazides
Authors: Knizek Jörg , Krossing Ingo , Nöth Heinrich , Schwenk Holger , Seifert Thomas
Published: July 2007

Monomeric Li(Ph)NN(Ph)SiMe3 · 2 OEt2 was obtained by deprotonating the respective hydrazine with nBuLi in the presence of diethyl ether. Reaction of NaN(SiMe3)2 with PhHN−N(SiMe3)2 in a benzene/tetrahydrofuran mixture provided monomeric Na(Ph)NN(SiMe · 3 THF, or Nd(Ph)NN(SiMe3)2 · THF using a small amount of THE Its TI IF ran be replaced by diethyl ether or tert‐butyl methyl ether to give 1:l solvates. These associate, forming chains in the solid state via ηn coordination (n = 2, 3) of their phenyl groups to the sodium centers of adjacent molecules. In contrast, not only deprotonation but also desilylation occurs on reaction of NaN(SiMe3)2 with H(Ph)NN(Ph)SiMe3 or of NaNH2 with (Me3Si)HNNPh2) The latter reaction results in the formation ot hexameric (NaHNNPh2)6 which adopts a face‐sharing double‐cubane structure.
Synthetic Routes to Transition‐Metal‐Substituted Pentadiynylidene Complexes
Authors: Hartbaum Cornelia , Fischer Helmut
Published: July 2007

Sequential reaction of the dimethylamino(ethynyl)carbene complex [(CO)5 WC(NMe2)CCH] (1) with nBuLi, CuI and BrCCSiMe3 affords the dimethylamino(trimethylsilylbutadiynyl)carbene [(CO)5WC(NMe2)CCCCSiMe3] (2). Desilylation of 2 with KF/THF/MeOH gives [(CO)5WC(NMe2)CCCCH] (3). The C‐stannylated carbene complex [(CO)5WC(NMe2)CCCCSnBu3] (4) is obtained by deprotonation of 3 with nBuLi and subsequent reaction with Bu3SnCl. Pd‐catalyzed coupling of complex 4 with [ClRu(CO),Cp] affords the heterobimetallic pentadiynylidene complex [(CO)5WC(NMe,)CCCCRu‐(CO)2Cp] (5) The analogous Fe derivative [(CO),WC(NMe,)CCCCFe(CO)2Cp] (6) is obtained by sequential reaction of 3 with nBuLi and [IFe(CO)2Cp] Similarly, treatment of 3 first with nBuLi and then with half an equivalent of HgCl2 affords the novel C4HgC4‐bridged biscarbene complex [(CO)3WC(NMe2)CCCCHgCCCCC(NMe2)W(CO)5]( 7 ) All new compounds are stable at room temperature. Spectroscopic data suggest weak interaction of the metal centers in 5 – 7.
Isolation and Characterization of a Porphinatomanganese(IV) Complex from the Reaction of Dichloro Monoxide with 5,10,15,20‐Tetrakis‐(2,6‐dichloropheny)porphinatomanganese(III) Chloride [Mn(EDCPP)CI]
Authors: Volz Heinrich , Müller Wihelm
Published: July 2007

The isolation at −78°C and characterization of the novel crystalline reactive porphinatomanganese(IV) complex Mn‐(TDCPP)(OCl)2(5) is described.5is compared with the porphinatomanganese(IV) complexes Mn(TDCPP)(C6H5IOCl)2(2), Mn(TDCPP)(C6F510C1)CI (3) and Mn(TDCPP)(OCH3)2, (4). The stoichiometric reaction of5with triphenylphosphane yields 2.5 equivalents of triphenylphosphane oxide and 1.0 equivalent of Mn(TDCPP)Cl (1). Complex5epoxidizes stilbene, and oxygenates and chlorinates cyclohexane.
A Decavandate Sandwiched by Diprotonated Cryptands‐222: Model for the Vanadate‐Ionophore Interaction
Authors: Farahbakhsh Mahin , Schmidt Häke , Rehder Dieter
Published: July 2007

Treatment of a C222‐vanadyl‐AMP complex (C222 = cryptand‐222, AMP = adenosine monophosphate) with Me2NH in the presence of air yielded centrosymmetric dihydrogen‐decavanadate H2V10O428, sandwiched by two diprotonated C222 molecules. An X‐ray crystal‐structure analysis was performed of this compound with the overall composition [C222(H+)2]2[H2V10O28] · 2 1/2, H2O. Protonation sites in the anion are μ2‐oxygen atoms linking two different vanadium centres. Protonation sites at the cryptand are the nitrogen and/or oxygen atoms of one of the −[CH2]2O[−CH2|2O|CH2]– bridges. The relevance of the compound for the stabilisation and transport of the kinase and phosphatase inhibitor decavanadate by biogenic ionophores is addressed.
Raman and Infrared Spectra and Quantum Chemical Calculations for Trichlorophosphoranylidenesulfamoyl Chloride, CISO2N=PCI3
Authors: áglvarez R. M. S. , Cutin E. H. , Mack H.‐G. , Della Védova C. O.
Published: July 2007

Raman (3500‐50 cm−l) and infrared (4000‐400 cm−l) spectra of the title compound, ClSO2NPCl3, were recorded for the solid and liquid phase. Additionally, the Raman spectrum of the compound dissolved in CCl4 was obtained and qualitative depolarization values were determined. The spectra of the liquid and solid phase were interpreted in terms of the existence of only one conformation possessing C1 symmetry, as predicted by quantum chemical calculations. A complete vibrational assignment is proposed based on the relative intensities, on group frequencies along with support from the normal coordinate analysis. The experimental fundamental vibrational modes are compared to those obtained from theoretical approaches employing the ab initio MP2/6‐31G* method and a density functional approximation (B3PW91/6‐31G*).
A New Efficient Synthesis of the Stilbenoid Laser Dyes BPS and Stilbene I by Palladium‐Catalyzed Coupling of Ethene with Bromoarenes
Authors: Rümper Jörg , Sokolov Viktor V. , Rauch Karsten , Meijere Armin De
Published: July 2007

The palladium‐catalyzed coupling of ethene with 4‐bromobiphenyl and 4′‐bromo‐4‐biphenylsulfonic acid permits a facile one‐pot preparation of the laser dyes (E)−4,4′‐diphenylstilbene (BPS, 3) and bis(triethylammonium) (E)−4,4′diphenylstilbene‐4″,4″‐disulfonate (6) in diastereomerically pure form on a multigram scale, with yields of 69 and 64%, repectively. The latter can easily be transformed to its dipotassium salt 7, the Stilbene I dye.
Synthesis, Redox Chemistry, and Mixed‐Valence Phenomena of Cyanide‐Bridged Dinuclear Organometallic Complexes
Authors: Zhu Nianyoung , Vahrenkamp Heinrich
Published: July 2007

21 new organometallic complexes of the type M–Cn–M′ containing the building blocks M, M′ = (CO)5Cr, (CO)5Mo, (CO)5W, Cp(CO)2Mn, Cp(CO)2Fe, Cp(CO)(CN)Fe, Cp(dppe)Fe, Cp(PPh3)2Ru, Cp(PPh3)Ni, and (PPh3)2Ag were obtained from the reagents M–Cn and M–X (X = leaving group). Among them are five pairs of linkage isomers M–CN–M′/M–NC‐M′. Structure determinations of (CO)5Cr–CN–M′ with M′ = Fe(dppe)Cp, Ni(PPh3)Cp, Ag(PPh3)2 and of (CO)5Cr–NC‐Fe(dppe)Cp have proved their identity and the linkage isomerism. Systematic variations of the v(CN) and v(CO) IR bands allow as assessment of the relative electron pair acceptor strengths of the building blocks M and M′ and a reliable identification of the individual linkage isomers. All dinuclear complexes are redox‐active, showing at lease one reversible oxidation. The redox potentials are characteristically dependent upon the nature of the building blocks M and M′ and upon the orientation of the cyanide link (CN vs. NC), 6 oxidized complexes of the type [M–Cn–Fe(dppe)Cp]+ were prepared chemically and isolated as PF6 or BF4salts. The molecular structure of [(CO)5Cr–CN–Fe(dppe)Cp]BF4 is not significantly different from those of the corresponding neutral Cr–CN–Fe or Cr–NC‐Fe complexes. Upon oxidation the v(CN) band of the complexes shifts to lower wavenumbers and becomes much more intense. The oxidized complexes show the paramagnetism due to one unpaired electron. They give rise to very intense metal‐to metal charge‐transfer bands in the near infrared region whose position was found to be characteristically dependent on solvent polarity of [(CO)5Cr–CN–Fe(dppe)Cp]BF4. A semiquantitative treatment of the optical and electrochemical measurements shows that the electron delocalization and metal–metal interaction in the oxidized dinuclear complexes is significant and that they belong to the class‐II mixed‐valence systems.
Evidence for Internal Ion Pair Formation upon Insertion of Reactive Alkene in the Zirconium–Carbon Bond of the cp2Zr(μ‐C4h6)b(c6f5)3 Metallocene‐Boron‐Betaine Ziegler Catalyst System
Authors: Karl Jörn , Erker Gerhard
Published: July 2007

Treatment of the (butadiene)ML2 complexes 1 [ML2 = Cp2Zr (a), Cp2Hf (b), and (.‐C5H4CH3)2Zr (c)] with B(C6F5)3 gives the 1:1 addition products (CH2CHCHCH2–B(C6F5_3)ML2 (3a–c). At –40°C the betaine complex 3a inserts one equivalent of methylenecyclopropane to give the regioisomeric insertion products 5a and 6a in a 60:40 ratio. These products exhibit the cyclopropylidene moiety in the α‐ and β‐positions, respectively, relative to zirconium. The corresponding hafnocene complexes 5b and 6b are obtained in a 70:30 ratio starting from 3b. The reaction of 3(a–c) with allene gives a single insertion product (7a–c) in each case where the exo‐methylene group is in the α‐position to the metal center ([2,1]‐insertion). The complexes 5–7 are chiral. They all exhibit a pronounced ·‐interaction of the internal –C4H=C5H− double bond of the s̀‐ligand chain with the metal center in addition to a metallocene/–C6H2–[B] ion pair interaction. The relative contributions of the cationic metallocene end of the dipolar complexes 5–7 are quite dependent on the steric and electronic properties of the respective metallocene units involved. This is revealed by a comparison to typical 13C‐NMR parameters of the complexes 5–7 with a pair of suitable model complexes, namely the ethylene insertion product 4 into the betaine system 3a and its THF adduct 4.THF.
Transition‐Metal‐Substituted Acylphosphanes and Phosphaalkenes, 35 Unprecedented Coupling of a Transition‐Metal Carbyne and a Methylene Phosphane Moiety – Structure of [Tp'(CO)2W=CP=C(NEt2)2] [Tp = HB (3,5‐Me2HC3N2)3]
Authors: Weber Lothar , Dembeck Gottfried , Boese Roaldn , Bläser Dieter
Published: July 2007

Condensation of [Tp](CO)2 Mčl] [1: M = Mo; 2: W; Tp] HB (3,5‐Me2HC2N2)3] with the inverse phosphaalkenes Me3 Sip=C(NR2)2 (3a: R = Me; 3b: Et) affords the novel phosphaalkenyl carbyne complexes [Tp](CO)2M.C–P=C(NR2)2] (a, b) (M = Mo; R = Me, Et) and 5a, b (M = W; R = Me, Et), which have been characterized by IR, 1H‐, 13C‐ and 31P‐NMR spectroscopy. In additon, the molecular structure of 5 has been elucidated by a single‐crystal X‐ray structure determination.
Coordination Polymers, 13. Induction of Helicity via Stereogenic Centers: Asymmetric Synthesis of (P)‐ and (M)‐Coordination Polymers
Authors: Saalfrank Rolf W. , Decker Michael , Hampel Frank , Peters Karl , von Schnering Hans Georg
Published: July 2007

Reaction of a methanolic copper(II) acetate solution of enantiomerically pure (5R)‐/(4S)‐methyl E‐(4‐ethyl‐2‐oxazolidinylidene)cyanoacetate 6 leads to the mononuclear chelate complexes (R, R)‐/ (S, S)‐7. Recrystallization of (R, R)‐/(S, S)‐7 from non‐coordinating chloroform and asymmetric induction via the stereogenic centers, originating from (R)‐/(S)‐6, stereospecifically yield the right‐ and left‐handed helical ID‐coordination polymers (P)‐/(M)‐8. The structures of mononuclear complex (R, R)‐7 and of helix (P)‐8 and its mirror image (M)‐8 have been characterised unequivocally by X‐ray crystal structure analyses. (P)‐ and (M)‐8 crystallize with chloroform to give the clathrates 1.{[CuLR2]. 2 CHCl3} and 1.{[CuLS2].2CHCl3}, respectively.
Chiral Arene Ruthenium Complexes, 2 A Diastereoselective Route to [η6‐Benzyl Alcohol)(COD)Ru] Complexes
Authors: Bodes Gegro , And Frank Heinemann , Zenneck Ulrich
Published: July 2007

Two preparative routes are reported that give access to the racemic series of planar chiral [(arene)(COD)Ru] derivatives containing η6‐bonded o‐tolyl ketone or aldehyde arene units. The ketone and aldehyde functions of these have subsequently been reduced by nBuLi and PhLi, respectively. Hydrolysis converts the initially formed lithium salts into diastereomeric benzyl alcohol complexes lithium salts into diastereomeric benzyl alcohol complexes in high yields. The formation of the new stereogenic centre is diastereoselective (88% de) for the aldehyde and diastereospecific for the ketone (de > 99%). Due to a sterically overcrowded situation, the rotation of the chiral side chain of [(COD) (η6–o‐tolyl‐tert‐butylphenylmethanol) Ru] (7) is hindered, as is the rotation of the phenyl and tert‐butyl substituents. As a consequence, the hydroxyl group is fixed at a position close to the metal both in solution and in the solid state.
Neutral Gold(I) Complexes with Mixed Phosphorus Ligands
Authors: Hollatz Christian , Schier Annette , Schmidbaur Hubert
Published: July 2007

The reaction of compounds (R3P) AuMe with diphenylphosphinous acid Ph2P(O)H affords methane and neutral complexes of the type (R3P(O)Ph2 (1a: R = Me; 1b: R = Ph, lc: R = o‐Tol). 1a, b are obtained in high yield, but the yield of lc is lower owing to a side‐reaction which leads to a different product: Ph2P(OH)–Au–P(O)Ph2 (2). The crystal structure of 1a was determined by a single‐crystal X‐ray diffraction study. The compounds is a monomer with a linear P–Au–P′ axis and the phosphane and phosphinite ligands in a staggered conformation. In solution (CHCl3, CH2Cl 2/) compounds 1a–c undergo a ligand redistribution, establishing equilibria that involve ionic isomers of the type [R3P)2Au]+ [Au‐(P(O)Ph2)2]−, which are readily identified through their NMR data. The analogous reaction of (R3P)b AuMe with dimethylphosphite (MeO)2P(O)H gives methane and the corresponding dimethylphosphites of the type (R3P)AuP(O)(OMe)2 (3a: R = Me; 3b: R = Ph; 3c: R= o‐Tol). The crystal structure of 3b has also been determined. It features a linear structure with an eclipsed conformation of the ligands. In polar solvents (CHCl3, methanol) there is again an eqilibrium between neutral and ionic isomers, the latter comprising bis(phosphane)gold cations [(R3P)2Au]+ and {Au[P(O)‐(OMe)2]2)− anions, as confirmed by NMR spectroscopy and mass spectrometry.
Synthesis and Structural Characterization of Mixed‐Ligand Oxorhenium(V) Complexes Containing Bidentate Dithioethers and Monothiolato Ligands
Authors: Reisgys Martina , Spies Hartmut , Johannesn Bernd , Pietzsch Hans‐Jergen , Leibnitz Peter
Published: July 2007

Neutral oxorhenium(V) complexes with dithioether ligands of the general formula [ReOX3(RS[CH2]2SR)], × = Cl, Br, R = nBu, Et, Bzl were synthesized. Ammonium perrhenate reacts in concentrated hydrochloric acid with dithiaalkanes (RS[CH2]2SR, R =nBu, Et, Bz) dissolved in glacial acetic acid to give octahedral complexes of the type [ReOCl3(RS[CH2]2SR)] (1a–c). In concentrated hydrobromic acid, nBu–S(Ch2)2S–nBu leads to the corresponding tribromo complexes (2). The X‐ray structure of shows a distorted octahedron with facial coordination of the bromide ligands. The sulfur atoms are cis coordinated to the terminal oxygen. Dissolution o f1a (R = nBu) in methanol leads to the substitution of the chloride trans to the oxo ligand by a meth oxy group. The resultant complex [ReOCl2(MeO) (nBu–S[CHL2]2S–nBu)] (3) is stable and can be isolated from methanolic solution, but changes to the μ‐oxo‐bridged dirhenium complex μ‐oxobis[dichloro(5,6‐dithiadidodecane)oxorhenium(V)] (4) when dissolved in other organic solvents. 1a reacts with an excess of benzenethiol by substitution of two chlorides to give the mixed‐ligand complex bis(benzenethiolate)chloro(5,8‐dithiadodecane)oxorhenium(V) (5a). The related 4‐methylbenzenethiolato complex 5b was synthesized starting from the μ‐oxo complex 4. X‐ray crystal structure determination of 5b shows the equatorial arrangement of the sulfur atoms. The trans position to the oxygen atom is occupied by a chloride ion.
Organo‐Substituted 1,2‐Dihydro‐1,2,5‐Disilaborepines
Authors: Wrackmeyer Bernd , Maisel Heidi E. , Milius Wolfgang
Published: July 2007

1,2‐Di‐1‐propynyl‐tetramethyldisilan (1) reacts with triorganoboranes R3B [R = Et (2a), CH2Ph (2c), 2‐thienyl (2d)], 9‐ethyl‐9‐borabicyclo[3.3.1]nonane (3), and diethyl(N‐pyrrolyl)borane (4) by twofold 1,1‐organoboration to give selectively the respective organo‐substituted 1,2‐dihydro‐1,2,5‐disilaborepines 5a‐d,6, and 7 in high yields. The compounds 5–7 were characterized by 1H‐, 11B‐, 13C‐, and 29Si‐NMR spectroscopy in solution. The molecular structures of the distance 1 and of the heterocycle 5c were determined by X‐ray structure analysis.
Troponin, B‐type natriuretic peptides and outcomes in severe heart failure: Differences between ischemic and dilated cardiomyopathies
Authors: Miller, Wayne L. , Hartman, Karen A. , Burritt, Mary F. , Burnett John C. , Jaffe, Allan S.
Published: July 2007

Background

Ischemic (ISCM) and idiopathic dilated (IDCM) cardiomyopathies have different responses to therapy and outcomes. Both may demonstrate elevations in troponin and B‐type natriuretic peptides, but biomarker levels have not been reported to differ as a function of the etiology of heart failure (HF). Accordingly, we compared these biomarkers in patients with chronic HF.

Hypothesis

Biomarker levels of troponin T, troponin I, B‐type natriuretic peptide (BNP), and N‐terminal prohormone brain natriuretic peptide (NT‐proBNP) are quantitatively different between ischemic and idiopathic dilated etiologies of chronic HF.

Methods

Forty patients (27 male, 68 ± 2 years; LVEF 25 ± 1%; NYHA Class III–IV) admitted to hospital for acute HF were studied. Biomarkers were drawn at admission prior to treatment intervention.

Results

Of the 40 patients, 27 had ISCM and 13 IDCM. Baseline clinical characteristics were similar with the exception of GFR. cTnT, cTnI, and BNP levels were higher in ISCM patients (cTnT: 0.373 ± 0.145 vs. 0.064 ± 0.016 ng/mL, p < 0.05; cTnI: 2.02 ± 0.76 vs. 0.21 ± 0.11 ng/mL, p < 0.05; BNP: 776 ± 91 vs. 532 ± 85 pg/mL, p < 0.05). Cardiovascular mortality during follow up (10 ± 1 months) was 48% in patients with ISCM and 23% with IDCM (p < 0.05).

Conclusions

Patients with acutely decompensated chronic HF have elevations in troponin and BNP. These elevations, as well as mortality are significantly higher in patients with ISCM compared to IDCM. The differential levels in biomarkers may be due to differences in disease pathogenesis, and fit with the adverse prognosis in these patients. Copyright © 2007 Wiley Periodicals, Inc.
Characteristics and in‐hospital mortality of diabetics and nondiabetics with an Acute Coronary Syndrome; the GREECS study
Authors: Pitsavos, Christos , Kourlaba, Georgia , Panagiotakos, Demosthenes B. , Stefanadis, Christodoulos
Published: July 2007

Objectives

In this work, we sought to describe the baseline characteristics and the management of patients with and without diabetes hospitalized with acute coronary syndromes (ACS), as well as to assess the prognostic value of diabetes status to the severity of ACS and in‐hospital mortality.

Methods

A sample of six hospitals located in Greek urban and rural regions was selected and we recorded almost all admissions due to ACS, from October 2003 to September 2004. 2,172 patients were included in the study. Socio‐demographic, clinical, dietary and other lifestyle characteristics was recorded.

Results

Approximately 1 in 3 patients admitted at the hospital with ACS had history of diabetes. Diabetes mellitus was associated with old age, female gender and more prevalent history of coronary heart disease, hypertension and renal failure. Diabetics sought medical care later and they were less likely to receive fibrinolytic therapy. No statistically significant difference was observed on severity of ACS between diabetics and nondiabetics. The in‐hospital mortality was higher in diabetics compared to nondiabetics. In a multivariate analysis only insulin‐treated diabetics had an increased mortality rate compared to nondiabetics.

Conclusions

The use of more effective medications and interventions must be used in diabetics who develop ACS, as well as educational efforts should be directed to those patients for reducing the pre‐hospital delay. Copyright © 2007 Wiley Periodicals, Inc.
QT dispersion and prognosis after coronary stent placement in acute myocardial infarction
Authors: Ueda, Hiroyasu , Hayashi, Tomoshige , Tsumura, Kei , Kaitani, Kazuaki , Yoshimaru, Kiyomichi , Nakayama, Yasunori , Yoshiyama, Minoru
Published: July 2007

Background

QT dispersion is increased in acute myocardial infarction (AMI), but the relation of QT dispersion to prognosis has not yet been fully elucidated.

Hypothesis

The purpose of this study is to evaluate prospectively whether QT dispersion is associated with the risk of major adverse cardiac events (MACEs) and mortality after successful coronary stenting in AMI.

Methods

One hundred and forty‐two patients with AMI and undergoing successful percutaneous coronary intervention (PCI) were enrolled in this study. Corrected QT dispersion was measured before and 24 h after PCI.

Results

During a period of 4477 person‐months, we confirmed 21 cases of MACE. Univariate analysis indicated that corrected QT dispersion before and 24 h after PCI, age, number of Q waves, and Killip > 2 were related to MACE and mortality. By multivariate analysis, corrected QT dispersion before PCI was an independent predictor of MACE and mortality, but corrected QT dispersion at 24 h after PCI was not statistically associated with MACE and mortality. Multiple‐adjusted hazard ratios for a 1 standard deviation (SD) magnitude increase in corrected QT dispersion before PCI were 2.24 (95% confidence interval, 1.36–3.68, p = 0.001) for MACE and 2.71 (95% confidence interval, 1.50–4.89, >) for mortality after adjustment for age, gender, ejection fraction, and Killip > 2.

Conclusions

Corrected QT dispersion before PCI is associated with an increased risk of MACE and mortality after successful PCI in patients with AMI. Copyright © 2007 Wiley Periodicals, Inc.
Influence of Intermolecular Interactions on the Formation of Tetra(carbomethoxy)‐tetrathiafulvalene Assemblies
Authors: Crivillers Núria , Mas‐Torrent Marta , Bromley Stefan T. , Wurst Klaus , Veciana Jaume , Rovira Concepció
Published: July 2007

We study the assemblies that tetra(carbomethoxy)tetrathiafulvalene (TCM–TTF) forms in solution and when deposited on a surface depending on intermolecular interactions and on the interactions with the substrate and the solvent. Its organization on graphite and mica substrates was studied by atomic force microscopy, and different molecular assemblies were observed depending on the prevailing interactions. The promotion of molecule–molecule interactions gave rise to the formation of molecular fibers. The investigation of the influence of the solvent–molecule interactions on TCM–TTF molecular organizations was carried out by UV/Vis spectroscopy, and a new TCM–TTF polymorph was obtained by changing the nature of the solvent. Finally, an explanation for all these phenomena, supported by computational modeling, is put forward.
Nonideal performance of analogue discrete networks
Authors: Bruton L. T. , Haslett J. W. , Atkins R. C.
Published: July 2007

Analogue delay lines, in the form of charge‐coupled or bucket‐brigade devices, are important network elements that may be used in connection with gain elements and summer–subtractor elements to realize microelectronic filters. This paper establishes invariant lower bounds on the sensitivity of the input–output transfer function to perturbations of the gains and delays of the analogue delay lines. Conventional sensitivity criteria, known as the Worst‐case and Schoeffler criteria, are used to represent the nonideal deviation of the transfer function.

It is demonstrated that, insofar as tolerance limitations are concerned, the conventional direct‐form structure (which is extensively employed to realize charge‐coupled‐device filters), is far inferior to the ladder structure.
Using least‐mean‐square‐approximation technique in filter design
Authors: Rakovich B. D.
Published: July 2007

The applications of the least‐mean‐square‐approximation technique to filter synthesis are discussed, and explicit expressions for the characteristic function of all‐pole lowpass filters are derived using a weighted least mean‐square error norm. The weight function depends on one variable parameter which controls the shape of the magnitude response both in the passband and in the stopband. It is shown that most of the filter functions in common use are special cases of this approximation procedure, including Legendre monotonic passband filters as a limiting, degenerate case. Also, a useful generalization of Legendre filter functions is proposed.
On the number of conductances required for realizing Y and K matrices
Authors: Naidu M. G. G. , Reddy P. S. , Thulasiraman K.
Published: July 2007

Upper bounds are established on the number of conductances required for realizing a real symmetric matrix Y as the short‐circuit conductance matrix of a resistive n‐port network containing no negative conductances, and for the realization of a real matrix K as the potential factor matrix of a similar network without negative conductances. These results are the consequence of the properties of the modified cut‐set matrix of an n‐port and a theorem in the theory of linear programming.
Resonant decoding for a class of nonsinusoidal microwave signals
Authors: Jackson J. Russell
Published: July 2007

Transmission‐line cascades are shown to exhibit the properties of a generator and resonance detector for a class of nonsinusoidal microwave signals. In providing a strong analogy to a well‐known phenomenon in the sinusoidal domain, this generator‐resonator matching is suggestive of possible applications in communications‐systems technology.
Continuously equivalent realizations of 3rd‐order paramount matrices
Authors: Naidu M. G. G. , Reddy P. S. , Thulasiraman K.
Published: July 2007

The continuously equivalent realizability of 3rd‐order real symmetric paramount matrices is discussed.
A class of nonrational impedances
Authors: Belevitch V.
Published: July 2007

The hypergeometric function p−1F(1, b; c; −p−2) is a positive real function of p for all real values of the parameters satisfying c ≧ b ≧ 0. The corresponding impedance is realizable as an LC‐ladder beginning with a unit shunt capacitance. The behavior on the j‐axis of this class of impedances is analysed.