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81.
Gianni Zotti Giuseppe Pilloni Mario Bressan Mario Martelli 《Journal of Electroanalytical Chemistry》1977,75(2):607-612
The electrochemical reduction of chlorodi-(1,3-bisdiphenylphosphinopropane)ruthenium(II)hexafluorophosphate, [RuCl(DPP)2](PF6), has been studied on the mercury electrode in 1,2-dimethoxyethane +0.1 M TBAP. The polarogram shows two reversible one-electron waves corresponding to the formation of [RuCl(DPP)2] and [RuCl(DPP)2]. Both products are unstable and decay through a disproportionation pathway and a fast internal metalation via Cl? elimination with formation of HRu(C6H4PPh·CH2CH2 CH2·PPh2)(DPP), respectively. The hypothesis is put forward that the geometry of a metal-complex can be one of the factors which allow us to obtain d7 monomeric complexes by electrochemical methods. 相似文献
82.
Giorgio Roma Aldo Ermili Alessandro Balbi Elda Massa Mario Di Braccio 《Journal of heterocyclic chemistry》1981,18(8):1619-1623
The reaction of 3-(dimethylamino)-1-oxo-1H-naphtho[2,1-b]pyran-2-carbaldehyde (Ia) with o-phenylenediamines or N-monosubstituted o-phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(8H)ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N-monosubstituted o-phenylenediamine hydrochlorides. The isolation of a significant intermediate as well as the synthesis through a different univocal pathway confirmed the structure of the compounds V. Moreover the reaction of Ia with N-monosubstituted o-phenylenediamines in refluxing pyridine generally afforded only low yields of compounds V, sometimes together with naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(13H)ones VII, isomers of V. 相似文献
83.
Wang X Andrews L Tam S DeRose ME Fajardo ME 《Journal of the American Chemical Society》2003,125(30):9218-9228
The reaction of laser-ablated Al atoms and normal-H(2) during co-deposition at 3.5 K produces AlH, AlH(2), and AlH(3) based on infrared spectra and the results of isotopic substitution (D(2), H(2) + D(2) mixtures, HD). Four new bands are assigned to Al(2)H(4) from annealing, photochemistry, and agreement with frequencies calculated using density functional theory. Ultraviolet photolysis markedly increases the yield of AlH(3) and seven new absorptions for Al(2)H(6) in the infrared spectrum of the solid hydrogen sample. These frequencies include terminal Al-H(2) and bridge Al-H-Al stretching and AlH(2) bending modes, which are accurately predicted by quantum chemical calculations for dibridged Al(2)H(6), a molecule isostructural with diborane. Annealing these samples to remove the H(2) matrix decreases the sharp AlH(3) and Al(2)H(6) absorptions and forms broad 1720 +/- 20 and 720 +/- 20 cm(-1) bands, which are due to solid (AlH(3))(n). Complementary experiments with thermal Al atoms and para-H(2) at 2.4 K give similar spectra and most product frequencies within 2 cm(-1). Although many volatile binary boron hydride compounds are known, binary aluminum hydride chemistry is limited to the polymeric (AlH(3))( solid. Our experimental characterization of the dibridged Al(2)H(6) molecule provides an important link between the chemistries of boron and aluminum. 相似文献
84.
Mario Chiesa Maria Cristina Paganini Elio Giamello Cristiana Di Valentin Gianfranco Pacchioni 《Chemphyschem》2006,7(3):728-734
(H+)(e-) pairs generated at the surface of polycrystalline CaO are analyzed for the first time in terms of the interaction of the unpaired electron spin with the nuclear spin of the 17O anions of the surface. CaO crystals enriched in the 17O isotope are prepared and the corresponding hyperfine coupling constants are measured in electron paramagentic resonance (EPR) spectra. The results are analyzed on the basis of cluster model density functional theory calculations. The computed hyperfine coupling constants for (H+)(e-) pairs formed on the edge, corner, and reverse corner sites of the CaO surface allow a tentative assignment of two observed spectral features to specific morphological surface sites. 相似文献
85.
86.
Mario Cetina Antonija Hergold-Brundić Ante Nagl Marijana Jukić Vladimir Rapić 《Structural chemistry》2003,14(3):289-293
The title compound was prepared by modified procedure and characterized by means of IR, [1H] and [13C] NMR spectroscopy. The structure was also determined by a single-crystal X-ray diffraction (XRD). 3-Ferrocenylpropanoic acid crystallizes as orange prisms in the triclinic space group P
with a = 7.645(1) Å, b = 7.953(1) Å, c = 9.961(1) Å, = 81.67(1), = 68.43(1), = 83.76(1), V = 556.3(1) Å3, Z = 2, R = 0.0435. In the ferrocene skeleton, Fe-C distances are in the range 2.033(2)–2.052(2) Å and C
C distances in the range 1.412(5)–1.431(3) Å. The angle defined by ring centers and Fe atom is 177.7(1). The cyclopentadienyl rings are twisted from the eclipsed conformation by 8.3(2) (average value). In the structure was observed strong intermolecular hydrogen bond of 2.670(3) Å forming cyclic dimers of the R2
2 (8) type. 相似文献
87.
Francesco Demartin Mario Manassero Mirella Sansoni Luigi Garlaschelli Secondo Martinengo 《Journal of organometallic chemistry》1983,243(1):C10-C12
The reaction of Ir6(CO)16 with a mixture of CO, H2, and ethylene yields the [Ir6(CO)15COEt]- anion, which has been shown by X-ray diffraction to contain an octahedral iridium cluster bearing a —bonded acyl group; the arrangement of the 11 terminal and 4 edge-bridging carbonyl groups is different from that found in both the analogous rhodium complex and the parent Ir6(CO)16 carbonyl. 相似文献
88.
Alberto Ballistreri Domenico Garozzo Mario Giuffrida Pietro Maravigna Giorgio Montaudo 《Journal of polymer science. Part A, Polymer chemistry》1986,24(2):331-346
The thermal fragmentation processes in poly-Schiff bases have been investigated by direct pyrolysis–mass spectrometry. The mass spectral data show that the thermal fragmentation occurring in the polymers under investigation is characterized by hydrogen transfer reactions. In the case of a totally aromatic poly-Schiff base (polymer I ), the thermal fragmentation process involves hydrogen transfer irom the methyne group with formation of fragments bearing nitrile and/or phenyl end groups. In the case of aromatic-aliphatic poly-Schiff bases (polymers II–IV ), the hydrogen transfer process occurs from the aliphatic methylene groups. The latter process involves a lower energy and therefore occurs at lower temperatures with respect to the totally aromatic polymer I , with formation of thermal fragments bearing olefin and/or imine end groups. Beside these fragments, several thermal fragmentation compounds are also evolved by multiple hydrogen transfer reactions. 相似文献
89.
Fiori J Bragieri M Zanotti MC Liverani A Borzatta V Mancini F Cavrini V Andrisano V 《Journal of chromatography. A》2005,1099(1-2):149-156
A previous GC/MS study highlighting the impurity profile of the synthetic pesticide d-allethrin is extended here to validate and confirm the impurities identity through the development of soft ionisation HPLC-MS methods. To accomplish this, we developed a reverse phase LC-MS analysis in gradient elution with two distinct soft ionisation techniques, the atmospheric pressure ionisation with electrospray source (API-ESI) and the chemical ionisation (APCI). A single quadrupole and an ion trap, which allowed the simultaneous determination of the molecular masses and structural information of the impurities by acquisition of collisionally induced (CID) product ions spectrum and in-source fragmentation, were employed as analysers. Single quadrupole and ion trap analysers resulted perfectly matching in the d-allethrin impurity fragmentation patterns. All the main impurities over 0.1% identified by GC/MS were confirmed. Results indicate that the proposed HPLC/MS method was found appropriate to confirm the presence of impurities such as chrysolactone, chloro allethrin derivatives, allethrolone and chrysanthemic acid, excluding their formation under GC/MS strong ionisation condition. 相似文献
90.
Summary An indirect analytical method, based on measurement of silver, for determining chloride and bromide in bismuth and lead tellurides was developed. The samples were dissolved in dilute nitric acid and the halides were separated as the silver salts by strong centrifugation. The excess of silver was directly determined in the sample solution by solvent extraction with dithizone in carbon tetrachloride and by spectrophotometric determination. Suitable conditions for masking interfering elements were established so that a very selective procedure for silver determination was achieved. Chloride and bromide down to 0.01 mole % could be determined. A procedure for determining chloride and bromide in the same sample with no interference from iodide, was also developed.
Zusammenfassung Ein indirektes, auf der Messung von Silber beruhendes Verfahren zur Bestimmung von Chlorid und Bromid in Wismut- und Bleitelluriden wurde entwickelt. Die Proben werden in verd. Salpetersäure gelöst und die Halogenide als Silbersalze scharf abzentrifugiert. Der Silberüberschuß wird unmittelbar aus dem Filtrat mit Dithizonlösung extrahiert und spektro-photometrisch gemessen. Geeignete Maßnahmen zur Maskierung störender Elemente wurden angegeben, so daß ein sehr selektives Verfahren zur Silberbestimmung vorliegt. Bis zu 0,01 Molprozent Chlorid und Bromid sind noch bestimmbar. Außerdem wurde ein Verfahren zur Chlorid- und Bromidbestimmung in Gegenwart von Jodid entwickelt.相似文献