Microwave and infrared spectra of deuterium-substituted germyl halides and the structures of the germyl halides

We have obtained microwave spectra of fully and partially deuterated germyl halides GeD₃X and GeHD₂X (X = F, Cl, Br, I) and analysed the infrared spectra in the GeH stretching region of the asymmetric species. The resulting A_o and B_o values have been combined with existing data on GeH₃X to give improved structures for the germyl halides. The values of the HGeX angles obtained show a correlation with GeH stretching frequencies, as in methyl compounds, but there appears to be no such correlation between stretching frequencies and GeH bond lengths.     

α-Elimination of organic halides from organotellurium(IV) halides

Three types of α-elimination (oxidative, photolytic, and thermal) of organotellurium(IV) halides to give organic halides have been disclosed. Treatment of organotellurium(IV) halides with some oxidants, preferably t-butyl hydroperoxide, in 1,4-dioxane, acetic acid, or acetonitrile affords the corresponding organic halides in good yields with retention of configuration and by ipso-replacement. The reactivity order of this α-elimination is roughly as follows: alkyl > aryl > alkenyl. The main reaction course seems to be a 1,2-tellurium halogen shift in unstable organotellurium(VI) compounds formed in situ by oxidation. Similar α-elimination also occurs by photolysis of these compounds with a high-pressure mercury lamp in benzene as the solvent. Here, a cross-coupling of the organic moiety with benzene scarcely occurs except for the cases of diaryltellurium(IV) dihalides. Neat pyrolysis of some alkyl(phenyl)tellurium(IV) dibromides at 200–250 °C (Kugelrohr distillation apparatus) again results in α-elimination to produce the corresponding alkyl bromides almost quantitatively.     

Cross-metathesis of allyl halides with olefins bearing amide and ester groups

An investigation was conducted to determine whether the cross-metathesis (CM) of allyl halides tolerates amide groups. The results show that the ruthenium-based complexes I–III serve as poor catalysts for the CM of allyl halides with olefins that contain an N,N-dimethylamide group. In contrast, the Grubbs–Hoveyda–Blechert second generation catalyst (III) efficiently promotes these processes with olefins bearing a Weinreb amide group. Lastly, a reinvestigation of the ester group tolerance of the allyl halide CM with unsaturated esters demonstrated that III serves as an efficient catalyst for these reactions.     

Correlation between the covalency and the thallium-205 nuclear magnetic resonance chemical shift in oxides and halides

²⁰⁵Tl chemical shift measurements were carried out on thallium(I) oxides and halides. A correlation between the chemical shift and the stereochemical activity of the 6s² lone pair of Tl^I was established; the greater this activity, the greater the absolute value of the chemical shift. For the halides, optical and chemical shift measurements gave access to the Tl-X bond ionicity via Ramsey's equation. In thallium(I) halides the absolute value of the chemical shift increases with the covalency. The work of Glaser on thallium(III) halides showed the chemical shift to decrease with increasing covalency. An explication of this difference is proposed. The hyperfine coupling constant A of the paramagnetic compound Tl₄MnI₆ was determined by the study of the chemical shift as a function of the susceptibility. This constant A is seen to be weak (−7 KG/μ_B).     

Sonogashira cross-coupling reactions with heteroaryl halides in the presence of a tetraphosphine-palladium catalyst

Heteroaryl halides undergoes cross-couplings with alkynes in good yields in the presence of [PdCl(C₃H₅)]₂/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as catalyst. A variety of heteroaryl halides such as pyridines, quinolines, a pyrimidine, an indole, a thiophene, or a thiazole have been used successfully. The reaction also tolerates several alkynes such as phenylacetylene and a range of alk-1-ynols. Furthermore, this catalyst can be used at low loading with some substrates.     

Stereo-recognizing transformation of (E)-alkenyl halides into sulfides catalyzed by nickel(0) triethyl phosphite complex

(E)-Alkenyl halides were transformed into (E)-alkenyl sulfides by the nickel(0) triethyl phosphite complex-catalyzed reaction with thiols, whereas (Z)-alkenyl halides gave alkynes under the same reaction conditions. Aryl halides were also transformed into aryl sulfides using the same reagent system.     

Decarboxylative trifluoromethylation of aryl halides using well-defined copper-trifluoroacetate and -chlorodifluoroacetate precursors

New synthetic routes to (NHC)copper-trifluoroacetate and -chlorodifluoroacetate complexes were developed (NHC = N-heterocyclic carbenes) so baseline reactivity patterns could be established for the decarboxylative trifluoromethylation of organic halides. In the presence of aryl halides, loss of CO₂ from these new precursors occurred at 160 °C concurrent with the formation of aryl-CF₃.     

Urea as ammonia equivalent in aryl halides amination catalyzed by palladium complexes

Urea reaction with nonactivated aryl bromides and chlorides under catalysis with palladium complexes led to the formation in 65–95% yield of triarylamines from para-and meta-substituted aryl halides and of diarylamines from ortho-isomers.     

Ternary zero-dimensional hybrid metal halides with dual emission

Bulk assemblies of zero-dimensional (0D) metal halides with ‘host-guest’ system provide a promising platform for rationally structural tunability and photoluminescence modulation. In this work, we first report a series of ternary 0D metal halides, (bmpy)₉[Pb₃Cl₁₁](MnCl₄)_2-2x(SbCl₅)_2x (bmpy⁺ = 1-buty-1-methylpyrrolidinium⁺, C₉NH₂₀⁺), where the organic cation bmpy⁺ cocrystallizes with [Pb₃Cl₁₁]^5- trimer clusters, [MnCl₄]^2? tetrahedra, and [SbCl₅]^2? pyramids. The emission color of (bmpy)₉[Pb₃Cl₁₁](MnCl₄)_2-2x(SbCl₅)_2x can be easily tuned from green to warm white and finally to orange-red by controlling the excitation wavelength or the [SbCl₅]^2?/[MnCl₄]^2? molar ratio, promising its potential for application in multicolor light-emitting devices or even in encrypting multilevel optical codes. This work presents a novel structural modulation strategy to fabricate superior ordered single-crystalline multicomponent materials with multifunctionalities of 0D luminescent metal halides.     

Reactivity of TEMPO anion as a nucleophile and its applications for selective transformations of haloalkanes or acyl halides to aldehydes

Sodium 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO⁻Na⁺), generated by reduction of TEMPO· with sodium naphthalenide in THF, reacted with alkyl halides or acyl halides to produce O-alkylated or acylated TEMPOs, which were in turn oxidized with mCPBA or reduced with DIBAL-H to afford the corresponding aldehydes, thus accomplishing a new protocol for the halides-carbonyls conversion.     

Reactions of vinyltributylgermanes and aryl halides under Heck conditions

We describe the palladium-mediated reaction of vinyltributylgermanes with aryl halides under Heck conditions. Depending on their degree of substitution, (E)-vinyltributylgermanes preferentially afford either the cine or Z-alkenyl coupled products in moderate yields. Substituents at the allylic position, especially oxygen, impact regio- and stereoselectivity.     

Stereospecific palladium-catalyzed borylation reaction of 1-alkenyl halides with diispropylaminoborane

The palladium-catalyzed borylation reaction of 1-alkenyl halides with diisopropylaminoborane leads efficiently and stereospecifically to the corresponding trans-1-alkenyl(diisopropylamino)boranes in good yields.     

Remarkable regioselectivity in microwave-enhanced palladium-catalyzed allylation reaction involving allyltrifluoroborates and aryl halides

An unprecedented cross-coupling reaction of potassium allyltrifluoroborates and aryl halides to the corresponding trans-β-methylstyrenes in the presence of PdCl₂(d^tbpf) catalyst under microwave heating was developed.     

Manganese-catalyzed cross-coupling reactions of aliphatic amines with aryl halides

An efficient and convenient protocol has been developed for the N-arylation of aliphatic amines with differently substituted aryl halides using a MnCl₂·4H₂O/l-proline catalyst and NaOt-Bu as the base in DMSO.     

Separation parameters in the reaction between volatile halides and hydrogen

Equations for calculating the separation coefficient and factor in reactions of volatile halides with hydrogen from the equilibrium constants of the corresponding reactions and initial reactant concentrations were obtained. The concept of the limiting impurity concentration was introduced. The values specified were calculated for the reduction of volatile chlorides with hydrogen.     

Dimethyl selenide complexes of copper,gallium and indium halides as potential precursors for selenium-containing chalcopyrite semiconducting materials

The coordination chemistry of copper, gallium and indium halides with the simplest possible selenoether i.e. Me₂Se was investigated with the aim to use the resulting complexes as precursors for selenium-containing chalcopyrite semiconducting materials. An optimized general procedure for the high yield synthesis is described and the influence of a halide ion on the structure and solubility of these metal halide dimethyl selenide complexes are discussed. These complexes were characterized by the elemental analysis, FT-IR and ¹H NMR spectroscopy as well as single crystal X-ray structures, the later study showing them to be monomeric for gallium halides, mono- or dimeric for indium halides and either an ion-pairs or 2-D extended structure in the case of copper halides.     

A Spectroscopic study of phenylboron halides

Phenylfluoroboranes have been prepared by the fluorination ofthe corresponding bromides with titanium tetrafluoride. The infrared spectra of the phenylhaloboranes, R_3−nBXn (RC₆H₅, XF, Cl, Br, I), have been recorded in the 4000–4250 cm⁻¹ region; an assignment of the fundamentals is suggested and characteristic frequency trends are discussed. An evaluation of the spectral data suggests that the structure of phenylfluoroboranes is distinctly different from that of the other halides in the series.     

One-pot synthesis of bromodifluoroacetimidoyl halides and its Suzuki coupling reactions with aryl boronic acids

N-aryl bromodifluoroacetimidoyl halides were prepared by the reaction of bromodifluoroacetic acid, triphenyl phosphine, p-arylaniline and triethylamine in tetrachloromethane in good yields. Palladium-catalyzed cross-coupling reaction of N-aryl bromodifluoroimidoyl iodide with arylboronic acids was realized to afford bromodifuoromethyl ketimine in good yields.     

Mechanism of the Ir/Pd catalyzed photocarboxylation of aryl halides

The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO_2 has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters.With the aid of density functional theory(DFT) calculations,the carboxylation starts with two parallel steps,i.e.,oxidative addition of aromatic halides on Pd~0 and reductive quenching of the photocatalyst Ir(ppy)_2(dtbpy)~+with amine.Thereafter,a successive oxidation of Pd~Ⅱ with the amine radical(generated by the reaction of cationic radical amine and Cs_2 CO_3) and Ir~Ⅱ species occurs to generate Pd~0,from which the carboxylation occurs easily via a coordination,Pd-C insertion step.The release of the carboxylate product then regenerates the catalyst.     

Remarkable reactivity enhancement with Sb?N inter-coordination of ethynyl-1,5-azastibocines in Pd-catalyzed cross-coupling reactions with organic halides

The reaction of 12-arylethynyl-6-methyl-5,6,7,12-tetrahydrodibenzo[c,f][1,5]-azastibocines with organic halides such as acyl halides and aryl halides in the presence of PdCl₂(PPh₃)₂ as a catalyst led to the formation of cross-coupling products, alkynyl ketones and diaryl acetylenes, in good yields. The reactivity of the ethynyl group on the 1,5-azastibocines was far superior to that on diphenyl(phenylethynyl)stibane, which brought about marked improvement in the reaction conditions (lower temperature and shorter reaction time) and in the yields of the cross-coupling products. Single-crystal X-ray analysis of the ethynyl-1,5-azastibocine showed the presence of intramolecular Sb?N interaction which should be responsible for the remarkable reactivity enhancement of the 1,5-azastibocines for this type of reaction.