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  • Inorganic Chemistry  (3,733)
  • General Chemistry  (3,093)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 384 (1971), S. 267-279 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metall(II) Halogenide reagieren mit Diisopropyl Methylphosphonat (DIMP) bei 150-220°C unter Bildung der folgende Komplexe: M[(C3H7O)CH3POO]2 (M = Fe, VO); M2[(C3H7O)CH3POO]2[OOP(CH3)-O-P(CH3)OO], (M = Ca, Mn, Co Ni); Zn[OOP(CH3)-O-P(CH3)OO]; Cu[CH3POO(OH)]3 (aus CuCl2 · 2 H2O + DIMP); Cu[CH3PO3] (aus CuX2 + DIMP; X = Cl, Br). Diese Komplexe wurden mittels Elektronen- und Infrarot-Spektren und magnetischen Messungen charakterisiert.
    Notes: Metal(II) halides react -with diisopropyl methylphosphonate (DIMP) at 150-220°C with formation of the following complexes: M[(C3H7O)CH3POO]2 (M = Fe, VO); M2[(C3H7O)CH3POO]2[OOP(CH3)-O-P(CH3)OO], (M = Ca, Mn, Co Ni); Zn[OOP(CH3)-O-P(CH3)OO]; Cu[CH3POO(OH)]3 (from CuCl2 · 2 H2O + DIMP); Cu[CH3PO3] (from CuX2 + DIMP; X = Cl, Br). These complexes were characterized by means of their electronic and infrared spectra and magnetic susceptibilities.
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  • 2
    ISSN: 0947-6539
    Keywords: cage compounds ; cobalt ; cyclic voltammetry ; fluorescence spectroscopy ; template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The template syntheses of various CoIII-hexaazaicosane-type cage complexes with aromatic substituents are described. The parent template, [Co(sen)]3+ ion {sen = 4,4′,4″-ethylidynetris(3-azabutan-1-amine)}, paraformaldehyde, a methyl aryl ketone and a base were reacted in acetonitrile to give aroyl substituents attached to the fully saturated sarcophagine cage (1-aroyl-8-methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]-icosane cobalt(III) ion) and aryl substituents attached to an analogous imine-type cage (2-aryl-8-methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosa-2-ene cobalt(III) ion). Phenyl, napthyl, phenanthryl, anthracenyl and anthraquinonyl substituents have been bound to the cage simply by this route to give molecules that can act as intercalators in DNA or as photosensitizers attached to reversible redox-active metal centres and can couple an organic two-electron reagent with an inorganic one-electron reagent. An X-ray crystallographic analysis of a phenanthroyl cage complex has also been carried out. These substances and their progeny should be useful as biological probes and fluorescent indicators and for energy capture and conversion.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 1434-1948
    Keywords: Insertion ; N ligands ; Terdentate ligands ; Rigid ligands ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel methyl complexes [Pd(Me)(N-N-N)]X (N-N-N = flexible or rigid terdentate nitrogen ligand, X = Cl, SO3CF3, BAr′4) have been synthesized and fully characterized. All complexes readily underwent insertion of carbon monoxide resulting in the quantitative formation of complexes [Pd{C(O)Me}(N-N-N)]X [X = Cl (1d-6d), BAr′4 (1e-6e)]. Subsequently, complexes 2e-6e underwent quantitative insertion of norbornadiene, resulting in complexes [Pd{C7H8C(O)Me}(N-N-N)]BAr′4 (2f-6f). Unexpectedly, these complexes, including even those containing rigid terdentate nitrogen ligands, possess a structure in which the nitrogen ligand is coordinated in a bidentate fashion. A kinetic study of the reaction of norbornadiene with complexes 1e-6e revealed that the reactivity of complexes 1e-6e toward norbornadiene increases with increasing rigidity of the terdentate ligand, i.e. with increasing strain in the PdN3 moiety, which indicates that insertion very likely occurs via a mechanism involving nitrogen dissociation. This is fully supported by ab initio MO calculations on CO and ethylene insertion into carbon-palladium bonds of cationic model systems containing a rigid terdentate nitrogen ligand, which showed that the lowest-energy pathway for both insertion reactions consists of substitution of one of the distal nitrogen atoms of the rigid terdentate nitrogen ligand by the substrate, followed by a rate-determining migratory insertion of the substrate into the carbon-palladium bond.
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  • 4
    ISSN: 1434-1948
    Keywords: Cyclopropanation ; Copper ; N ligands ; Macrocycles ; Supported catalysts ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CuI and CuII complexes of cyclic and open-chain polyaza compounds have been tested as catalysts in the benchmark cyclopropanation reaction of styrene with ethyl diazoacetate. In general, only small amounts of copper are needed to promote the reaction. The catalytic activity depends on the structure of the ligand, e.g. amine-amides are more efficient than polyamines, and on the oxidation state of copper, CuII being more active than CuI. Given that CuI is the active species, these changes of behavior must be related to the stabilities of the complexes. The nature of the counterion also has a noticeable influence on the catalytic activity, the role of which is discussed. XAS measurements suggest the formation of oligomeric species. Some of the chiral ligands lead to small enantiomeric excesses. Open-chain ligands can easily be supported on organic polymers and their complexes can be used as catalysts. Furthermore, cyclic and acyclic complexes can be supported on clays by cation exchange and the solids obtained tend to promote the reaction with a decrease in the trans/cis ratio.
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  • 5
    ISSN: 0947-6539
    Keywords: amphiphiles ; block copolymers ; dendrimers ; micelles ; surfactants ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new class of amphiphilic macromolecules has successfully been synthesized by creating well-defined diblock copolymers of polystyrene (PS, Mn=3.2 × 103, Mw/Mn=1.04) with poly-(propylene imine) dendrimers. A poly-styrene core molecule with a primary amine end-group was prepared by a quantitative three-step modification procedure of acid-functionalized polystyrene. On this core molecule, five different generations from PS-dendr-NH2 up to PS-dendr-(NH2)32 were constructed in high yields. The molecular structure of the block co-polymers was analyzed in detail with NMR and IR spectroscopy and electrospray mass spectrometry. With conductivity measurements and monolayer pressure-area isotherm determinations, we observed generation-dependent amphiphilic behavior. Dynamic light scattering and transmission electron microscopy showed that amphiphile geometry had a distinct effect on aggregation behavior; this is in qualitative agreement with Israelachvili's theory. Critical association concentrations determined with the pyrene probe luminescence technique were as low as 5 × 10-7 M. The amphiphiles presented here, therefore, show a resemblance to traditional block copolymers with regard to size and stability, and are similar to surfactants with respect to tuning of the shape.
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  • 6
    ISSN: 0947-6539
    Keywords: chiral mesophases ; Langmuir-Blodgett films ; liquid crystals ; phthalocyanines ; supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure and physical properties of optically active, metal-free 2,3,9,10,16,17,23,24-octa (S-3,7-dimethyloctoxy)phthalocyanine ((S)-Pc(8,2)) are reported and compared with those of the phthalocyanine with (R,S) side chains (mixture of 43 stereoisomers). Unlike the latter compound, (S)-Pc(8,2) lacks a crystalline phase. A freshly prepared sample is in a distorted mesophase and reorganizes irreversibly to a more ordered phase above 65 °C. X-ray diffraction and circular dichroism studies indicate that the molecules are stacked in columns which have a hexagonal arrangement and a left-handed helical superstructure, that is, a novel chiral Dh* mesophase. Solid state NMR measurements reveal that the phthalocyanine units in the columns begin to vibrate laterally when the temperature is increased. At 111 °C (Dh* → Dr transition) they start to rotate around their columnar axes and at the same time the side chains become liquidlike. Energy migration is very efficient in the chiral Dh* phase and also in the frozen mesophase below 3 °C, as follows from luminescence spectroscopy. Intracolumnar charge transport, studied by the time-resolved microwave conductivity technique, turns out to be slower in the helically distorted columns than in linear columns. (S)-Pc(8,2) forms a very stable bilayer at the air-water interface, which can be transferred to give a high quality Langmuir-Blodgett film. The fact that this phthalocyanine is mesogenic at room temperature is thought to be responsible for this behavior.
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  • 7
    ISSN: 0947-6539
    Keywords: calixarenes ; carcerands ; inclusion compounds ; molecular devices ; resorcinarenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 11 calix[4]arene-based carceplexes obtained by solvent or doped inclusion is reported. Carceplexes with amides, for example, DMF, NMP, and 1,5-dimethyl-2-pyrrolidinone, and sulfoxides, for example, DMSO and thiolane-1-oxide, were obtained by solvent inclusion. In these cases the yield of the carceplex decreases with increasing guest size. Potential guests that do not form carceplexes by solvent inclusion, such as 2-butanone and 3-sulfolene, could be incarcerated by doped inclusion with 1,5-dimethyl-2-pyrrolidinone as a solvent “doped” with 5-15 vol% of potential guest. The amide bridges of the carceplexes were converted into thioamide bridges in essentially quantitative yield by means of Lawesson's reagent in refluxing xylene. The dynamic properties of the incarcerated guests were examined by 2D NMR spectroscopy. Whereas for most guests a preference for one orientation inside the calix[4]arene-based (thia)carcerands was observed, for DMA, NMP, and ethyl methyl sulfoxide inside calix[4]arene-based (thia)carcerands two different orientations were present. The energy barriers for interconversion between the various orientations of DMA, NMP, and ethyl methyl sulfoxide inside calix[4]arene-based (thia)-carcerands were determined with 2D EXSY NMR. The energy barriers are higher for the thiacarcerands than for the corresponding carcerands with amide bridges. This may be due to the stronger hydrogen-bond-donating character of the thioamide group. Furthermore, molecular modeling simulations indicate that in case of the thiacarcerand the cavity is smaller as a result of a smaller diametrical distance between the NH atoms. Our results demonstrate that molecular modeling can be used to estimate the energy barriers for interconversion; the calculated activation energies showed good quantitative agreement with the experimental values.
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  • 8
    ISSN: 0947-6539
    Keywords: bioorganic chemistry ; carbohydrates ; glycosides ; peptide bonds ; phytochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two suitably protected building blocks (11 and 33) for the preparation of amide-linked heptaglucoside mimetic 2, an analogue of the naturally occurring phytoalexin elicitor 1a, were readily accessible by glycal chemistry. Sequential elongation of terminal glucuronide 21 with laminaribiosyl hemiaminal 33 and anomeric amine 11 by EDC/HOBt-catalyzed condensation and two-step conversion of the C6-OTr moiety into the corresponding carboxylate function afforded homogeneous carbopeptoid 2 in high overall yield. It was found that replacement of the acetal linkages by the more rigid amide bonds destroys the phytoalexin-elicitor activity.
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  • 9
    ISSN: 1434-1948
    Keywords: Rhodium ; N ligands ; Carbonyl complexes ; Methoxycarbonyl ; Dinuclear complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 1,4,7-trimethyl-1,4,7-triazacyclononane (Cn*) with [{(CO)2Rh(μ-Cl)}2] in methanol at 0°C, followed by the addition of NH4PF6, results in the formation of the mononuclear carbonyl complex [Cn*Rh(μ-CO)2]PF6 ([1]PF6), the dinuclear carbonyl complex [Cn*Rh(μ-CO)3RhCn*](PF6)2 {[2](PF6)2} and the dinuclear methoxycarbonyl complex [Cn*Rh(C(O)OMe)(μ-CO)2RhCn*]PF6 ([3]PF6). The reaction of [2](PF6)2 with NaOMe results in formation of [3]PF6 by the attack of the methoxide at a bridging carbonyl. Treatment of [3]PF6 with NH4PF6 regenerates [2](PF6)2, thus showing that the methoxylation of [2](PF6)2 is reversible. The structures of [1]PF6, [2](PF6)2 and [3]PF6 have been determined by single-crystal X-ray diffraction. For [3]PF6 an unprecendented facile, reversible, migration of the C(O)OMe ligand between the two rhodium centres of the Rh(μ-CO)2Rh core is observed.
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  • 10
    ISSN: 1434-1948
    Keywords: Rhodium ; Iridium ; N ligands ; Coordination modes ; Polymerizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of [RhI(cod)]+ and [IrI(cod)]+ by the new pyridine-amine-pyrrole ligands Py-CH2-N(R)-CH2-Pyr-H (HLR; R = H, Bzl, Bu) and the corresponding pyridine-amine-pyrrolate ligands [Py-CH2-N(R)-CH2-Pyr]- (LR-; R = H, Bzl, Bu, CH2Py) has been investigated. The neutral ligands HLR (R = H, Bu, Bzl) give [(HLR)MI(cod)]+ (M = Rh, Ir) in which HLR acts as a didentate ligand via the pyridine nitrogen (NPy) and the amine nitrogen (NRamine). The crystal structures of [(HLH)MI(cod)]PF6 (M = Rh: [1]PF6 and M = Ir: [2]PF6) have been determined. Deprotonation of [(HLR)MI(cod)]+ (M = Rh, Ir; R = H, Bzl, Bu) results in the neutral complexes [(LR)MI(cod)] (M = Rh, Ir) of the mono-anionic ligands LR- (R = H, Bzl, Bu). In square-planar [(LH)MI(cod)] (M = Rh: 3, M = Ir: 4), LH- is didentate via NHamine and the pyrrolate nitrogen (NPyr). The X-ray structures of 3 and 4 reveal that in both cases the uncoordinated NPy accepts a hydrogen bond from NHamine. The X-ray structures of [(LBzl)MI(cod)] (M = Rh: 5, M = Ir: 6), show that LBzl- is didentate via Namine and NPyr for M = Rh and tridentate for M = Ir. In solution LBzl- is tridentate for both M = Rh and M = Ir. The neutral complexes [{Py-CH2-N(R)-CH2-Pyr}MI(cod)] (M = Rh, Ir) cannot be oxidised selectively with H2O2. This is in marked contrast to the previously observed selective oxidation of the corresponding cationic complexes [{Py-CH2-N(R)-CH2-Py}RhI(cod)]+. Rhodium complex 5 is an active catalyst for the stereoregular polymerisation of phenylacetylene, whereas iridium complex 6 is inactive.
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