Cyclometallated 1,2,3-triazol-5-ylidene iridium(III) complexes: synthesis,structure, and photoluminescence properties

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Distribution of benzo-substituted crown-ethers between chloroform and water: effects of macrocycle ring size and lithium chloride

Small size benzo-substituted crown ethers are attractive complexing agents for lithium isotope separation by solvent extraction. Low transfer of the crown ethers from solvent to water is a key point for applicability of the extractants. In the present study, 9- and 12-membered crown ethers were synthesized, and their distribution between chloroform and water was studied. Polyether ring size, benzene substituents and addition of LiCl to water were found to effect on distribution constants. Low losses of the macrocycles were observed at single-stage contact with aqueous phase. However, these losses should be taken into account in the design of multistage processes for the preparation of highly enriched lithium isotopes.     

Addition Polymerization of 5-Ethylidene-2-Norbornene in the Presence of Pd N-Heterocyclic Carbene Complexes

New high-performance catalytic systems based on Pd N-heterocyclic carbene complexes for the selective addition polymerization of 5-ethylidene-2-norbornene (ENB) were proposed. With these catalysts, polymerization can be conducted at unprecedentedly high monomer/catalyst ratio (up to 5 × 10⁵/1) and gives high-molecular-weight soluble polymers with good film-forming properties. Varying the polymerization conditions (reaction temperature, monomer and catalyst concentrations, monomer/Pd ratio) makes it possible to prepare soluble ENB-based addition polymers with specified molecular weights in reasonable yields.     

Insights into the reaction paths of copper(i) acetylides with dichloroglyoxime leading to 3,3′-biisoxazoles

Russian Chemical Bulletin - Base-free reaction of dichloroglyoxime with copper(i) acetylides gave 3,3′-biisoxazoles via a nucleophilic substitution of the chlorine atom of dichloroglyoxime...     

Solvent-free telomerization of isoprene with alcohols catalyzed by palladium(ɪɪ) carbene complexes

Russian Chemical Bulletin - The effect of various factors on the activity and selectivity of palladium N-heterocyclic carbene (NHC) complexes in the telomerization of isoprene with alcohols has...     

Coupling of aromatic aldehydes with aryl halides in the presence of nickel catalysts with diazabutadiene ligands

Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.     

8-Methoxy-5-methyl-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-cyclopenta[<Emphasis Type="Italic">a</Emphasis>]naphthalene: synthesis and reactivity

A new single-step approach to cyclopenta[a]naphthalenes through TiCl₄-catalyzed reactions of 1-trimethylsilyloxycyclopentene with arylacetaldehydes was proposed. 8-Methoxy-5-methyl-2,3-dihydro-1H-cyclopenta[a]naphthalene and its derivatives were studied in oxidation and bromination reactions, as well as in hydrolytic cleavage of the O-Me bond.     

Addition homo- and copolymerization of 3-triethoxysilyltricyclo[4.2.1.0<Superscript>2,5</Superscript>]non-7-ene

New norbornene type monomer bearing reactive triethoxysilyl group was synthesized, and its addition homo- and copolymerization with 3-trimethylsilyltricyclonon-7-ene was studied. The target monomer was obtained using regio- and stereospecific [2σ+2σ+2π] cyclo-addition of quadricyclane with vinyltrichlorosilane followed by the reaction of the formed cycloadduct with ethanol in the presence of triethylamine. Addition polymerization was investigated over the three-component Pd-containing catalytic system (Pd complex, Na+[B(3,5-(CF₃)₂C₆H₃)₄]–(cocatalyst) and tricyclohexylphosphine). The N-heterocyclic carbene Pd complex (SIPrPd(cinn)Cl) with high activity and tolerance to the Si—O—C moieties was used as a catalyst. The yields of the homo- and copolymers were 24—68% depending on the monomer (comonomer): Pd: B: PCy₃ ratio. The obtained addition polymers are high-molecular-weight amorphous products, the glass transition temperature of which exceeds 300 °C. The presence of reactive Si(OC₂H₅)₃ groups in the homo- and copolymers made it possible to carry out a hard-to-realize cross-linking involving side substituents and followed by the formation of insoluble polymers.     

Synthesis of 5′,6′,7′,7A′-tetrahydrospiro[cyclohexane-1,4′-inden]-2′(1′<Emphasis Type="Italic">H</Emphasis>)-one and 1′,2′,6′,7′-tetrahydrospiro[cyclohexane-1,4′-inden]-3′(5′<Emphasis Type="Italic">H</Emphasis>)-one

The paper describes the preparation methods for two tetrahydroindanones of spiro structure.     

Arylation of nitromethane with sterically hindered aryl halides

Efficient conditions for Pd-catalyzed cross-coupling of sterically hindered aryl halides with nitromethane were developed to give corresponding aryl nitromethanes. The opportunity to carry out the reaction of polynitromethylation under these conditions was demonstrated, as well as to use the obtained products in the synthesis of bisnitrile oxides.