Luminescent Colloidal InSb Quantum Dots from Generated Single-Source Precursor.

Despite recent advances, the synthesis of colloidal InSb quantum dots (QDs) remains underdeveloped, mostly due to the lack of suitable precursors. In this work, we use Lewis acid-base interactions between Sb(III) and In(III) species formed at room temperature from commercially available compounds (, InCl, Sb[NMe] and a primary alkylamine) to obtain InSb adduct complexes. These complexes are successfully used as precursors for the synthesis of colloidal InSb QDs ranging from 2.

1,2-Addition of Diethylzinc to a Bis(Imidazolyl)ketone Ligand.

In this study, the selective 1,2-addition of diethylzinc to the ketone functionality of BMIK [bis(1-methyl-4,5-diphenylimidazolyl)ketone] is shown. The reaction product is isolated in a dimeric form with a planar Zn(µ-O)-motif keeping the two monomers together. This compound can serve as a model for reactive intermediates in the catalytic alkylation of ketones with diorganozinc reagents.

Arylazoindazole Photoswitches: Facile Synthesis and Functionalization via SAr Substitution.

A straightforward synthetic route to arylazoindazoles via nucleophilic aromatic substitution is presented. Upon deprotonation of the NH group, a CF-substituted formazan undergoes facile cyclization as a result of intermolecular nucleophilic substitution (SAr). This new class of azo photoswitches containing an indazole five-membered heterocycle shows photochemical isomerization with high fatigue resistance.

Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using C NMR and Comprehensive GC × GC.

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative C nuclear magnetic resonance (C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake.

Spectroscopic Characterization of a Monomeric, Cyclopentadienyl-Based Rhenium(V) Dioxo Complex.

Mononuclear, coordinatively unsaturated rhenium(V) dioxo species of the type XReO2 (X = Me, substituted cyclopentadienyl) have long been postulated as intermediates in rhenium-catalyzed deoxydehydration, but their characterization was precluded because of aggregation into dimeric or oligomeric structures. Using the bulky 1,2,4-tri-tert-butylcyclopentadienyl (Cp(ttt)) ligand, the rhenium(V) dioxo species (Cp(ttt))ReO2 could now be observed, in equilibrium with the dimeric form [(Cp(ttt))Re(O)μ-O]2, and characterized by NMR, IR, and UV-vis spectroscopies, as well as electrospray ionization mass spectrometry. (Cp(ttt))ReO2 is shown to be the primary product of reduction of the rhenium(VII) complex (Cp(ttt))ReO3 with PPh3 and demonstrated to react with ethylene glycol significantly faster than its dimeric counterpart, supporting its role as an intermediate in rhenium-catalyzed deoxydehydration reactions.

Directed ortho-lithiation: observation of an unexpected 1-lithio to 3-lithio conversion of 1-lithio-naphthyllithium compounds with an ortho-directing 2-(dimethylamino)methyl group.

Regioselectivity is an important aspect in the design of organic protocols involving Directed ortho-Lithiation (DoL) of arenes, in particular with those arenes containing heteroatom substituents as directing groups. The DoL of 2-[(dimethylamino)methyl]naphthalene (dman) that proceeds with low regioselectivity was revisited by varying both the nature of the lithiating reagent (either n-BuLi or t-BuLi) and/or the solvent (pentane or diethyl ether); the 3-deuterated substrate, 3-Ddman, was also investigated as a substrate to compare to that of dman. The 3-lithio regioisomer exists as tetranuclear [2-(Me2NCH2)C10H6Li-3]4, 1, both in the solid state (X-ray) and in solution (NMR).

Mechanistic insights into the rhenium-catalyzed alcohol-to-olefin dehydration reaction.

Rhenium-based complexes are powerful catalysts for the dehydration of various alcohols to the corresponding olefins. Here, we report on both experimental and theoretical (DFT) studies into the mechanism of the rhenium-catalyzed dehydration of alcohols to olefins in general, and the methyltrioxorhenium-catalyzed dehydration of 1-phenylethanol to styrene in particular. The experimental and theoretical studies are in good agreement, both showing the involvement of several proton transfers, and of a carbenium ion intermediate in the catalytic cycle.

Catalytic deoxydehydration of diols to olefins by using a bulky cyclopentadiene-based trioxorhenium catalyst.

A bulky cyclopentadienyl (Cp)-based trioxorhenium compound was developed for the catalytic deoxydehydration of vicinal diols to olefins. The 1,2,4-tri(tert-butyl)cyclopentadienyl trioxorhenium (2) catalyst was synthesised in a two-step synthesis procedure. Dirhenium decacarbonyl was converted into 1,2,4-tri(tert-butyl)cyclopentadienyl tricarbonyl rhenium, followed by a biphasic oxidation with H2 O2 .

Hetero-aggregate compounds of aryl and alkyl lithium reagents: a structurally intriguing aspect of organolithium chemistry.

Organolithium compounds are often depicted as mononuclear species. However, such compounds are in fact aggregated species and can form hetero-aggregates containing different organic groups, including heteroatom groups. In reactions involving organolithium reagents, the "pure" homo-aggregate organolithium compound can change into a hetero-aggregate, which has a different structure and reactivity to the homo-aggregate.

Diastereoselective self-assembly of chiral diamine-chelated aryllithiums to dimeric aggregates.

Aryllithium compounds [LiC6H4(CH2N(Et)CH2CH2NEt2)-2]2 (2b), [LiC6H4(CH(Me)N(Me)CH2CH2NMe2-(R))-2]2 ((R)-3b), and [LiC6H4(CH(Me)N(Me)CH2CH2NMe2-(rac))-2]2 ((rac)-3b) were synthesized and characterized in the solid state and in solution. X-ray crystallographic studies of 2b and (R)-3b and molecular weight determinations of 2b, (R)-3b, and (rac)-3b by cryoscopy in benzene showed that, both in the solid state and in apolar, noncoordinating solvents such as benzene, these compounds exist as discrete dimeric aggregates. For (R)-3b and (rac)-3b the aggregation process of two monomeric aryllithium units to one dimer is highly diastereoselective.

Formation of organolithium hetero-aggregates [Li4Ar2(nBu)2] (Ar=C6H4CH(Me)NMe2-2) during the directed ortho-lithiation of [1-(dimethylamino)ethyl]benzene.

(R)-[1-(Dimethylamino)ethyl]benzene reacts with nBuLi in a 1:1 molar ratio in pentane to quantitatively yield a unique hetero-aggregate (2 a) containing the lithiated arene, unreacted nBuLi, and the complexed parent arene in a 1:1:1 ratio. As a model compound, [Li(4)(C(6)H(4)CH(Me)NMe(2)-2)(2)(nBu)(2)] (2 b) was prepared from the quantitative redistribution reaction of the parent lithiated arene Li(C(6)H(4)CH(Me)NMe(2)-2) with nBuLi in a 1:1 molar ratio. The mono-Et(2)O adduct [Li(4)(C(6)H(4)CH(Me)NMe(2)-2)(2)(nBu)(2)(OEt(2))] (2 c) and the bis-Et(2)O adduct [Li(4)(C(6)H(4)CH(Me)NMe(2)-2)(2)(nBu)(2)(OEt(2))(2)] (2 d) were obtained by re-crystallization of 2 b from pentane/Et(2)O and pure Et(2)O, respectively.

Copper(I) thiolate catalysts in asymmetric conjugate addition reactions.

[structure: see text] Full conversion and enantioselectivities up to 83% have been obtained in the conjugate addition reactions of diethyl zinc to Michael acceptors catalyzed by well-defined (chiral) copper(I) aminoarenethiolates. Interesting differences between organozinc or Grignard reagents have been found: for cyclic enones R(2)Zn reagents afford better results, whereas earlier work showed that RMgX reagents react more selectively with acyclic enones.

The first homologous series of self-assembled aryl bromo- and aryl cyanocuprates, -argentates, and -aurates; MLi(2)XAr(2) (M = Cu(I), Ag(I), Au(I); X = Br, C(triple bond)N; Ar = [C(6)H(4)CH(2)N(Et)CH(2)CH(2)NEt(2)-2]-).

Reaction of 2 molar equiv of the diamine chelated aryllithium dimers Li(2)(C(6)H(4)[CH(2)N(Et)CH(2)CH(2)NEt(2)]-2)(2) (Li(2)Ar(2)) with the appropriate metal bromide allows the synthesis of the first homologous series of monomeric group 11 bromoate complexes of type MLi(2)BrAr(2) (M = Cu (7), Ag (8), Au (9)). Both in the solid state and in solution, the bromocuprate 7 is isostructural with the bromoargentate 8. The crystal structures of 7 and 8 consist of a MLi(2) core, and each of the two aryl ligands bridges via electron-deficient bonding between the group 11 metal and one Li atom (d(C(ipso)-M) = 1.

Selective Hydrovinylation of Styrene in a Membrane Reactor: Use of Carbosilane Dendrimers with Hemilabile P,O Ligands.

A codimerization of styrene and ethene can be carried out continuously in a nanofiltration membrane reactor with dendritic Pd complexes such as 1. The selectivity of the reaction is increased considerably under continuous conditions. The activity and selectivity of monomeric model complexes and the dendritic catalysts were compared in batch reactions.

A Proposal for Positive Cooperativity in Anion-Cation Binding in Yttrium and Lutetium Complexes Based on o-Amino-Substituted Phenolate Ligands. On the Way to Coordination Polymers by Self-Assembly. Molecular Structures of [ClLu(OAr)(3)Na] (X-ray) and [ClY(OAr')(3)Y(OAr')(3)Na] (X-ray and (89)Y-NMR).

Unique hetero(poly)metallic complexes [ClM(OAr)(3)Na] (M = Lu (3a), Y (3b)) and [ClY(OAr')(3)Y(OAr')(3)Na] (4) containing the bis (OAr = OC(6)H(2)(CH(2)NMe(2))(2)-2,6-Me-4) and mono (OAr' = OC(6)H(4)(CH(2)NMe(2))-2) o-amino-substituted phenolate ligands have been synthesized and characterized by NMR ((1)H, (13)C, and (89)Y) and X-ray structure determinations (3a and 4). Crystals of 3a are triclinic, space group P&onemacr;, with unit cell dimensions a = 10.706(1) Å, b = 14.