Showing papers on "Pyridine published in 1983"

Direct, regiospecific 2-lithiation of pyridines and pyridine 1-oxides with in situ electrophilic trapping

Abstract: La lithiation est faite en presence de perfluoroacetone ou de SiClMe 3 : obtention de pyridines et de leur N-oxydes substitues en 2 ou disubstitues en 2,6

Photochemistry of MLCT excited states. Effect of nonchromophoric ligand variations on photophysical properties in the series cis-Ru(bpy)2L22+

Abstract: Proprietes photophysiques des etats excites (transfert de charge metal a coordinat) emissifs, a vie courte, d'une serie de complexes cis-Ru(bpy) 2 L 2+ , (L= pyridine, pyridazine, 1/2, phenanthroline, 1/2 bipyridine, N'-methylimidazole, (amine-2 ethyl)-2 pyridine)

Chemistry of ruthenium. 12. Reactions of bidentate ligands with diaquabis[2-(arylazo)pyridine]ruthenium(II) cation. Stereoretentive synthesis of tris chelates and their characterization: metal oxidation, ligand reduction, and spectroelectrochemical correlation

Abstract: Formation de chelates tris RuBL 2 x+ (x=1 ou 2) avec B=coordinat bidente et L=pap ou tap. Etude electrochimique dans l'acetonitrile

Facile C–H activation by lutetium–methyl and lutetium–hydride complexes

Abstract: Bis(pentamethylcyclopentadienyl)lutetium complexes Lu(η5-C5Me5)2R (R = Me, H) react at 20–50 °C in hydrocarbon solvents with benzene, pyridine, the ylide CH2PPh3, and tetramethylsilane to give stable, isolatable products of C–H activation, i.e. metallation at a carbon of the reagent with extrusion of R–H.

Synthesis of SS'-bis(4'-benzo[15-crown-5]dithioglyoxime and its complexes with copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), platinum(II), and platinum(IV)

Abstract: NN′-Bis(4′-benzo[15-crown-5])diaminoglyoxime (H2L) has been prepared as a bis(sodium chloride) salt from anti-dichloroglyoxime, 4′-aminobenzo[15-crown-5], and sodium bicarbonate in ethanol. Copper(II), nickel(II), and cobalt(II) complexes of H2L·2NaCl have a metal–ligand ratio of 1 : 2 and the ligand co-ordinates through the two N atoms, as do most of the vic-dioximes. [Pt(HL)2·4NaClO4] and [Pd(HL)2·4NaClO4] complexes form six-membered chelate rings and co-ordinate through N and O atoms. [Co(HL)2(L′)Cl·4NaClO4] has been prepared with L′= triphenylphosphine or pyridine, together with a chloride ion, as axial ligands. H2L·2NaX (X = Cl– or ClO4–) reacts with UO2(O2CMe)2·2H2O to give complexes with a metal–ligand ratio of 1 : 1. All these complexes are soluble in water; n.m.r., i.r., and u.v.–visible data are presented.

A new procedure for the oxidation of saturated hydrocarbons

Abstract: The oxidation of adamantane can be achieved with unusual efficiency using molecular oxygen and a system comprising hydrogen sulphide and iron powder in pyridine containing acetic acid and a little water.

Picosecond laser photolysis studies of deactivation processes of excited hydrogen bonding complexes. 3. Detection of the nonfluorescent charge-transfer state in the excited 1-aminopyrene-pyridine hydrogen bonded pair and related systems

Abstract: Etude par photolyse laser (ps) du mecanisme d'extinction de fluorescence du systeme amino-1 pyrene-pyridine. Formation d'un compose par transfert de charge non fluorescent dans la paire excitee (D*-H...A). Comparaison avec les systemes N,N-dimethylamino-1 pyrene-cyano-4 pyridine et amino-1 pyrene-cyano-1 pyridine

Investigations of the nature of dehydrogenation of the α-carbon atom in the oxidation of amines coordinated to ruthenium

Abstract: The oxidations of the amine complexes Ru(bpy)₂(A-B)²⁺ (where A-B = ampy [2-(aminomethyl)pyridine], d₂-ampy [2-(1,l-dideuterioaminomethyl)pyridine], and Meampy [2-( 1-aminoethy1)pyridinel and bpy = 2,2'-bipyridine) in aqueous solution to the corresponding imine species have been studied by using flash photolysis techniques. The rate-determining step of the reaction involves removal of a hydrogen from the a-carbon atom and the concomitant intramolecular transfer of two electrons from ligand to metal. Deuterium exchange and deuterium isotope effect studies, and stereochemical arguments, are consistent with a mechanism involving either (i) a hydride transfer from C to Ru or (ii) a base (solvent water)-assisted proton abstraction. Chirality studies indicate no loss of configurational integrity about the metal center during oxidation, which favors the second proposal. The X-ray crystal structure of the more rapidly oxidized diastereoisomer of [Ru(bpy)₂(Meampy)]S₂O₆.5H₂O it to be the λS(δR) form, in which the methyl substituent on the a-carbon atom is equatorial and the hydrogen substituent axial.

Cellulose-Based Liquid Crystalline Polymers; Esters of (Hydroxypropyl) Cellulose

Abstract: Propionic, n-butyric, isobutyric and phthalic acid esters of (hydroxypropyl)cellulose were prepared and characterized. The aliphatic esters were readily formed by reacting (hydroxypropyl)cellulose with the corresponding acid chloride at room temperature. The phthalic acid ester was formed by reacting phthalic anhydride with (hydroxypropyl)cellulose in pyridine at 45°C. The bulk aliphatic esters exhibit cholesteric reflection in the visible range of the spectrum. The wavelength of the reflection peak maximum, Λo, was measured spec-trophotometrically at different temperatures. Plots of Λo reached zero (i.e. the cholesteric pitch became infinite) at temperatures close to the anisotropic-isotropic phase transition temperatures. The latter temperatures were determined experimentally by polarizing micros-copy and differential scanning calorimetry, and were in the range 165°C ± 10°C for all cellulose derivatives studied in this work. The optical rotatory dispersion (ORD) and circular dichroism (CD) of t...

Organic chemistry of subvalent transition metal complexes. Part 7. Desulfurization of dibenzothiophene by nickel(0) complexes: evidence for electron transfer in oxidative additions

Abstract: Two equivalents of the complex (2,2'-bipyridyl)(1,5-cyclooctadiene)nickel(0) cleave dibenzothiophene in homogeneous media to form nickel-substituted biphenyl derivatives and nickel sulfide. The cleavage proceeds more readily in tetrahydrofuran (THF) than in benzene solution, and excess amine (either bipyridyl or pyridine) retards the reaction. Neither biphenylene nor 2-phenylbenzenethiol was a detectable transient in the desulfurization process. The possible fleeting formation of biphenylene was ruled out by a study of the desulfurized products obtained from the 2,8-dimethyl and the 3,7-dimethyl derivatives of dibenzothiophene. A possible role of nickel hydride in some of the C-S bond cleavage is suspected from the observed effects of either acid or lithium aluminum hydride (LiAlH/sub 4/) used in the workup of the reaction mixture. The reaction is not catalytic in nickel when an excess of LiAlH/sub 4/ is used; indicating that Ni(0) cannot be regenerated from NiS under these conditions. The observed cleavage of approx. 50% of the dibenzothiophene by 2 equiv of (2,2'-bipyridyl)(1,5-cyclooctadiene) nickel ((C/sub 10/H/sub 8/N/sub 2/)Ni(C/sub 8/H/sub 12/)) is ascribed to the gradual formation of bis(cyclooctadiene) nickel ((C/sub 10/H/sub 8/N/sub 2/)/sub 2/Ni) which is ineffectual in cleaving dibenzothiophene. Finally, the relative reactivity of the dibenzothiophenes (dibenzothiophene > 2,8-dimethyldibenzothiophene >> 3,7-dimethyldibenzothiophene), the relative effectiveness of amine donorsmore » or solvents, and the observed hydrogen abstraction from the solvent are interpreted in terms of an electron-transfer mode of action by the nickel(0) desulfurizing agent.« less

Preparation and molecular stereochemistry of metalloporphyrin complexes with cyano ligands. Cyano(pyridine)(meso-tetraphenylporphinato)iron(III) hydrate and cyano(meso-tetraphenylporphinato)manganese(III) chloroform solvate

Abstract: (Ia) reagiert in einer Pyridin-CHC13-Losung in 24 h zu (Ib) (Ausb. in mg), das ebenso wie das aus (IIa) und KCN in heisem EtOH dargestellte (IIb) (Ausb. in mg) mit Z=4 in der RG P21/n kristallisiert.

Synthesis of pyridine functionalised, sterically hindered lithium and copper (I) alkyls; crystal structures of [{2-(Me3Si)2C(M)C5H4N}2](M = Li or Cu), dimeric compounds free of multicentre bonding

Abstract: Reactions of 2-bis (trimethylsilyl) methylpyridine, (1), with LiBun in hexane–diethyl ether, and LiBun in tetrahydrofuran followed by CuCl, yields thermally robust binuclear complexes [{2-(Me3Si)C2(M)C5H4N}2] for M = Li and M = Cu respectively in which the metal is not involved in electron deficient bonding, being bound by Cα of one ligand and the nitrogen of a centrosymmetrically related ligand and has a close metal contact [M ⋯ M 2.560(9)(Li) and 2.412(1)A(Cu)].

Isomeric 2-(arylazo) pyridine complexes of OsCl2 and OsBr2

Abstract: Synthese, spectres UV-visible et propriete redox des complexes OsX 2 L 2 ou X=Cl et Br et L=phenylazo- ou m-tolylazo-2 pyridine

[Me3Si(py)]⊕X⊖ (X = Br,I): X-Ray Structural Analysis of the 1:1-Adducts of Bromo- or Iodotrimethylsilane and Pyridine

Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 973. DOI:10.1002/anie.198309730

Coordination intercalation reactions of the layered compounds vanadyl phosphate (VOPO4) and vanadyl arsenate (VOAsO4) with pyridine

Abstract: Vanadylphosphat und -arsenat, auch in ihren hydratisierteh Formen, reagieren mit Pyridin zu koordinierten Einlagerungsverbindungen.

Cycloaddition von Amino-, Phosphino- und Thionitrilen sowie Phosphinoisocyaniden an die Azido-Liganden planarer Rhodium(I)-, Iridium(I)-, Palladium(II)- und Platin(II)-Verbindungen: Tetrazolyl-Chelatkomplexe

Abstract: Amino-, Phosphino- und Thionitrile werden an die Azidliganden planarer d8-Verbindungen von PdII, PtII, RhI und IrI unter Bildung von 5-R-Tetrazolato-Komplexen 2–8 addiert. Neuartige Chelat-Komplexe 9, 10, 12–15, 17 werden mit 2-Pyridincarbonitril, (2-Cyanethyl)diphenylphosphan, (2-Cyanphenyl)diphenylphosphan bzw. (2-Isocyanethyl)diphenylphosphan erhalten, wobei Cycloaddition und Bindung des Pyridin-N-Atoms bzw. der Diphenylphosphinogruppe an das Metall erfolgt. Cycloaddition of Amino-, Phosphino-, Thionitriles, and Phosphinoisocyanides to the Azide Ligands of Planar Rhodium(I), Iridium(I), Palladium(II), and Platinum(II) Complexes: Tetrazolyl Chelate Complexes Amino-, phosphino-, and thionitriles are added by 1,3-cycloaddition to the azide ligands of planar RhI, IrI, PdII, and PtII, compounds to give the 5-R-tetrazolato complexes 2–8. Using 2-pyridinecarbonitrile, (2-cyanoethyl)diphenylphosphane, (2-cyanophenyl)diphenylphosphane or (2-isocyanoethyl)diphenylphosphane new chelate complexes 9, 10, 12–15, 17 have been obtained via cycloaddition and bonding of the pyridine N-atom or the diphenylphosphino group, respectively, to the metal atom.