Ether Adduct Research Articles

Hydrogallation of Alkynes with H−GaCl2: Formation of Organoelement Dichlorogallium Compounds Potentially Applicable as Chelating Lewis Acids

Treatment of trimethylsilylethynylbenzenes C6H6-x(C[TRIPLE BOND]C-SiMe3)x(x=1-3) with the hydridodichlorogallium compound H-GaCl2 afforded, almost quantitatively, the alkenylphenyl compounds C6H6-x[C(H)C(SiMe3)-GaCl2]x[x=1 (6), 2 (7), and 3 (8)] by hydrogallation. Only compound 6 was readily soluble in n-hexane; it formed dimers via Ga-Cl bridges. The bisalkenyl compound 7 was only sparingly soluble; its molecular structure consisted of a singular dimeric formula unit with a cyclophane-type constitution and two bridging Ga 2Cl 2 heterocycles. The overall structure may be described by a molecular box formed by a large macrocycle comprising 22 Ga, C, and Cl atoms. Compound 8 proved to be insoluble in hydrocarbon solvents. Its molecular structure could not be detected. Extraction of the solid raw products of 7 and 8 with diethyl ether yielded small quantities of the ether adducts C6H6-x[C(H)C(SiMe3)-GaCl2(OEt2)]x(x=2, 3) [7(OEt2)2 and 8(OEt2)3], both of which are monomeric because of the coordinative saturation of their gallium atoms. The tetraalkyne 1,2,4,5-tetrakis(trimethylsilylethynyl)benzene gave a different reaction course. Complete hydrogallation resulted in the release of 2 equiv of GaCl3, and neighboring alkenyl groups of the product 9 were connected by GaCl bridges to form seven-membered heterocycles and an overall tricyclic compound. Compound 9 was characterized as a diethyl ether adduct.

A Classical Silver Carbonyl Complex [{MeB[3‐(Mes)pz]3}Ag(CO)] and the Related Silver Ethylene Adduct [{MeB[3‐(Mes)pz]3}Ag(C2H4)

A Classical Silver Carbonyl Complex [{MeB[3‐(Mes)pz]₃}Ag(CO)] and the Related Silver Ethylene Adduct [{MeB[3‐(Mes)pz]₃}Ag(C₂H₄)

A Classical Silver Carbonyl Complex [{MeB[3‐(Mes)pz]3}Ag(CO)] and the Related Silver Ethylene Adduct [{MeB[3‐(Mes)pz]3}Ag(C2H4)

Durch Elektronenreichtum stabilisiert: Ein thermisch stabiler Silber(I)-Ethylen-Komplex und das erste klassische Silber(I)-Carbonyl-Addukt (siehe Struktur) wurden mithilfe des nichtfluorierten, relativ elektronenreichen Scorpionatliganden [MeB{3-(Mes)pz}3]− (Mes=2,4,6-Trimethylphenyl, pz=Pyrazolat) hergestellt.

Structural Variations of Silver Ethylene Complexes Supported by Boron-Protected Fluorinated Scorpionates and the Isolation of a Ligand-Directed Silver Helix

Silver(I) ethylene adducts [PhB(3-(CF3)Pz)3]Ag(C2H4) and [MeB(3-(CF3)Pz)3]Ag(C2H4) have been synthesized using the corresponding lithium salts, AgOTf, and ethylene. X-ray data show that [PhB(3-(CF3)Pz)3]Ag(C2H4) has a planar three-coordinate silver center whereas [MeB(3-(CF3)Pz)3]Ag(C2H4) features a tetrahedral silver site. The ethylene-free {[PhB(3-(CF3)Pz)3]Ag}n adopts a helical structure with a hexagonal pore.

Gallium sulfide and indium sulfide nanoparticles from complex precursors: Synthesis and characterization

Nanocrystalline gallium sulfide (Ga 2S 3) and indium sulfide (In 2S 3) have been prepared by a two-step process. The first step involves metathesis reaction of trimethyl gallium/indium ether adduct (Me 3Ga/In·OEt 2) with 1,2-ethanedithiol (HSCH 2CH 2SH) resulting in the formation of a polymeric precursor. The precursor complex has been characterized using Ga/In analysis, IR, proton NMR and mass spectroscopy. The thermal behavior of both complexes has been studied using thermogravimetric (TG) analysis. In the second step, these precursor complexes have been pyrolysed in furnace under flowing nitrogen atmosphere whereupon they undergo thermodestruction to yield nanometer-sized particles of gallium/indium sulfide. The nanoparticles obtained were characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS). The average size of the nanoparticles ranged from 10 to 12 nm for Ga 2S 3 and 20 to 22 nm for In 2S 3, respectively. This is the first report on use of a binary single source precursor to synthesize β-Ga 2S 3 nanoparticles.

Iridium-catalyzed addition of methanol to terminal alkynes

The 18-crown-6 (18C6) ether adduct of sodium hexachloroiridate [Na(18C6)] 2[IrCl 6]· xH 2O ( 1) was found to catalyze an addition of methanol to a variety of nonfunctionalized alkynes RC CH (R = H, n Pr, n Bu, n Pen, Ph, HC C(CH 2) 4) yielding the corresponding Markovnikov addition products (ketals) and in the cases of hex-1-yne and hept-1-yne also anti-Markovnikov ones (acetals, <10%). Furthermore, the reaction of methanol with octa-1,7-diyne resulted in a double Markovnikov addition to only one triple bond, yielding 7,7-dimethoxyoct-1-yne with 80% degree of conversion. On the other hand, the regioselectivity in an addition of methanol to functionalized terminal alkynes of the type RC(O)C CH (R = OMe, Me) was found to be towards anti-Markovnikov products (70–93%). In these two cases vinyl ether intermediates were observed NMR spectroscopically in the course of the reactions.

Iridium-catalyzed addition of methanol to internal alkynes

The 18-crown-6 (18C6) ether adduct of sodium hexachloroiridate [Na(18C6)] 2[IrCl 6]· xH 2O ( 1) was found to catalyze an addition of methanol to a wide variety of internal alkynes RC CR′ (R/R′ = Et/Et, Me/Et, Me/ nPr, Me/ nBu, Me/ tBu, Me/Ph, Et/ nPr, Et/Ph) yielding the corresponding ketals and, due to the presence of water traces, their hydrolysis products (ketones). The regioselectivity of the addition of methanol to unsymmetrically disubstituted internal alkynes is governed by steric and electronic factors, being the highest in the case of pent-2-yne, hex-2-yne and hept-2-yne (80–85%). In the case of MeC CCO 2Me, an alkyne having an electron-withdrawing substituent, the addition was found to be 100% regioselective, with two methoxy groups going to the side away from an ester group. Furthermore, in the analogous addition of methanol to MeO 2CC CCO 2Me, besides the vinyl ethers ( E)/( Z)-MeO 2CC(OMe) CHCO 2Me, a cyclotrimerization product (C 6(CO 2Me) 6) was also observed. A comparison of the catalytic potential of other iridium compounds in the addition of methanol to hex-3-yne revealed that all examined ionic hexachloroiridates ([Na(18C6)] 2[IrCl 6]· xH 2O, Na 2[IrCl 6]·6H 2O, H 2[IrCl 6]·6H 2O, Na 3[IrCl 6]· xH 2O) were catalytically active, whereas [IrCl(CO)(PPh 3) 2] and [(IrCl 2Cp*) 2] were found to be almost inactive (degree of conversion <10%). However, the best results were obtained for the crown ether adduct 1. Moreover, in the addition of CD 3OD to hex-3-yne, [Na(18C6)] 2[IrCl 6]· xH 2O ( 1) was also found to catalyze a H/D exchange of protons in the neighborhood of a keto group or a quaternary carbon of a ketal with a degree of deuteration >97%.

Syntheses of Highly Fluorinated 1,3,5-Triazapentadienyl Ligands and Their Use in the Isolation of Copper(I)−Carbonyl and Copper(I)−Ethylene Complexes

Fully fluorinated triazapentadienyl ligand [N{(C3F7)C(C6F5)N}2]- and the related [N{(C3F7)C(2-F,6-(CF3)C6H3)N}2]- have been synthesized in good yield via a convenient route and used in the isolation of three- and four-coordinate copper(I)-carbon monoxide complexes. They show fairly high nu(CO) values (>2100 cm(-1)), indicating the presence of electron-poor Cu sites. The copper(I)-ethylene adduct [N{(C3F7)C(C6F5)N}2]Cu(C2H4), featuring a three-coordinate Cu site, has also been synthesized using [N{(C3F7)C(C6F5)N}2]CuNCCH3 and C2H4.

New Insight into Reactions of Ni(S2C2(CF3)2)2 with Simple Alkenes: Alkene Adduct versus Dihydrodithiin Product Selectivity Is Controlled by [Ni(S2C2(CF3)2)2]- Anion

The nickel bis(dithiolene) complex Ni(S2C2(CF3)2)2 employs its sulfur centers in reactions with alkenes, and stable interligand S-bonded alkene adducts can be formed. The present study shows that the selectivity of alkene binding to charge-neutral Ni(S2C2(CF3)2)2 is influenced by the anion [Ni(S2C2(CF3)2)2]-. In the absence of anion, formation of substituted dihydrodithiins (intraligand addition) dominates, whereas the presence of anion allows for the formation of stable interligand adducts. Mechanistic implications are discussed. The X-ray crystal structure of the ethylene adduct of Ni(S2C2(CF3)2)2 is presented, displaying interligand binding of ethylene to sulfur centers in the bis(dithiolene) complex.

The First Carbene Complex of a Diorganoberyllium: Synthesis and Structural Characterization of Ph2Be(i-Pr-carbene) and Ph2Be(n-Bu2O)

The reaction of base-free Ph2Be with 1,3-di-isopropyl-4,5-dimethylimidazol-2-ylidene (i-Pr-carbene) in toluene gave the carbene adduct Ph2Be(i-Pr-carbene) (1) as colorless crystal blocks. For comparison, the di-n-butyl ether adduct Ph2Be(n-Bu2O) (2) was prepared from BeCl2 and PhLi in a mixture of Et2O and n-Bu2O. Single-crystal X-ray determinations reveal monomeric solid-state structures for both complexes.

β‐Arylthio‐α‐chloroalkyl Ethers — Novel 1,1‐Bis‐electrophiles for Geminal Alkylation.

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β‐Arylthio‐α‐chloroalkyl Ethers — Novel 1,1‐Bis‐electrophiles for Geminal Alkylation

AbstractA novel protocol for geminal alkylation is suggested based upon the consecutive generation of two cationoid intermediates from the easily prepared adducts of arylsulfenyl chlorides and vinyl ethers. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)

An overview of organic molecule soft ionization using vacuum ultraviolet laser radiation

The utility of coherent vacuum ultraviolet (VUV) single-photon ionization (SPI) combined with time-of-flight mass spectrometry (TOF-MS) for organic molecule detection by parent mass is explored in this short review. Nonresonant tripling in phase-matched Xe–Ar gas mixtures was used to generate photons at a fixed energy of 10.5 eV. Representative organic molecules with different functional groups were examined, including aliphatic and aromatic alkanes, alkenes, alkynes, alkanols, ethers, amines, aldehydes, ketones, carboxylic acids, and esters. In almost every case, the intensity of the resultant parent molecular ion peak detected by TOF-MS was found to be superior to that obtained using 70 eV electron impact (EI), and comparable to that obtained with 12 eV EI. In those instances when fragmentation reactions did occur, the resultant ions were similar to those found using EI but with significantly reduced mass spectral intensities. It was still possible to establish one dominant fragmentation pathway that could be used for molecular identification even if the parent molecular ion was not the strongest feature in the spectrum, for example, in the case of alcohols, alcohol clusters, and alcohol–ether adducts. Several of the fragment ions were metastably broadened. Not surprisingly, their known appearance energies or estimated reaction enthalpies were very similar to the fixed photon energy used. The success of using VUV for organic molecule soft ionization is attributed to the low photon energy that removes predominantly a π- or non-bonding electron from the functionalized species. As most organic compounds have ionization potentials in the 10.5 eV region, this approach is expected to be near universal.Key words: vacuum ultraviolet laser, single photon ionization, organic molecule detection, soft-ionization, mass spectrometry.

Olefin Metathesis Reactions Initiated by d2 Molybdenum or Tungsten Complexes

Dimeric or monomeric imido complexes of Mo(IV) or W(IV) will slowly catalyze some olefin metathesis reactions, although it is estimated that <2% of the d2 species is “activated” by the olefin. An ethylene adduct of {W(NAr‘)[OCMe2(CF3)]2}2 can be isolated, which upon heating is transformed into a new dimeric species that contains an ethyl group and a CH activated ortho methyl group in the NAr‘ ligand.

Strukturen der Alkalimetallsalze aromatischer, heterocyclischer Amide: Synthese und Struktur von Kronenether‐Addukten der Alkalimetall‐Carbazolide

Structures of Alkali Metal Salts of Aromatic, Heterocyclic Amides: Synthesis und Structure of Crown Ether Adducts of the Alkali Metal CarbazolidesThe synthesis of six alkali metal carbazolide crown ether complexes is reported: Potassium‐carbazolide(18‐crown‐6) (1), rubidium‐carbazolide(18‐crown‐6) (2), rubidium‐carbazolide(15‐crown‐5) (3), cesium‐carbazolide(18‐crown‐6) (4), cesium‐carbazolide‐bis(15‐crown‐5) (5), and cesium‐carbazolide‐bis(benzo‐15‐crown‐5) (6). The complexes 1 to 6 were synthesized from the alkali metal carbazolide (obtained in solution by metalation of carbazole with KH or Rb‐ and Cs‐hexamethyldisilazide) and the corresponding crown ether. The structures of 1, 3, 4, and 5 could be determined by X‐ray diffraction. Complex 1 is mononuclear, the carbazolide anion shows an η1(N)‐coordination to the metal cation. The complexes 3 and 4 are dinuclear with a central metal2N2‐ring. Compound 5 has a salt‐like structure with a sandwich‐like [Cs(15‐crown‐5)2]+ cation and an uncoordinated carbazolide anion.

Synthesis and Characterization of MO[OSi(OtBu)3]4 and MO2[OSi(OtBu)3]2 (M = Mo, W): Models for Isolated Oxo-Molybdenum and -Tungsten Sites on Silica and Precursors to Molybdena− and Tungsta−Silica Materials

The tri(alkoxy)siloxy complexes MO[OSi(OtBu)3]4 (1, M = Mo and 2, M = W) were prepared from MOCl4 and LiOSi(OtBu)3. Similarly, reactions of MO2Cl2(DME) with LiOSi(OtBu)3 afforded the new siloxide complexes MO2[OSi(OtBu)3]2 (3, M = Mo and 4, M = W), which are themally unstable at ambient temperature. More stable compounds were obtained by the crystallizations of 3 and 4 in a coordinating solvent, to form the ether adducts MoO2[OSi(OtBu)3]2(THF) (3a) and WO2[OSi(OtBu)3]2(DME) (4a). These compounds serve as soluble models for isolated molybdenum or tungsten atoms on a silica surface and were characterized by 1H, 13C, 29Si, 95Mo, and 183W NMR, FT-Raman, FT-IR, and UV−vis spectroscopies. Compounds 1, 2, 3a, and 4a were used to prepare metal−oxide silica composites via the thermolytic molecular precursor method. The xerogels obtained from the thermolyses of 1, 2, 3a, and 4a in toluene contained mesoporosity with surface areas of 10, 230, 106, and 270 m2 g-1, respectively. Despite the high surface areas for most samples, these xerogels contain MO3 domains. Complexes 1 and 2 were also used to introduce molybdenum and tungsten sites, respectively, onto mesoporous SBA-15 silica via displacement of the −OSi(OtBu)3 ligand for a siloxyl group from the silica surface. All molybdenum- and tungsten-containing systems were tested as catalysts for the epoxidation of cyclohexene using tert-butyl hydroperoxide (TBHP) or aqueous H2O2 as the oxidant.

Strukturen der Alkalimetallsalze aromatischer, heterocyclischer Amide: Synthese und Struktur von Kronenether‐Addukten der Alkalimetall‐Pyrrolide

AbstractStructures of Alkali Metal Salts of Aromatic, Heterocyclic Amides: Synthesis und Structure of Crown Ether Adducts of the Alkali Metal PyrrolidesThe synthesis of eight alkali metal pyrrolide crown ether complexes is reported: Lithium‐pyrrolide(12‐crown‐4) (1), sodium‐pyrrolide(15‐crown‐5) (2), potassium‐pyrrolide(18‐crown‐6) (3), rubidium‐pyrrolide(18‐crown‐6) (4), cesium‐pyrrolide(18‐crown‐6) (5), cesium‐pyrrolide(18‐crown‐6)(H2O)0.5 (6), rubidium‐pyrrolide(15‐crown‐5)2 (7), and rubidium‐hydrogendipyrrolide(15‐crown‐5)2 (8). The complexes 1 to 5 and 7 were synthesized from the alkali metal pyrrolide and the corresponding crown ether. Compound 6 was obtained from 5 and water, complex 8 from RbN(SiMe3)2, pyrrole, and 15‐crown‐5. The structures of 1, 2, 3, 4, 6, 7, and 8 could be determined by X‐ray diffraction. The complexes 1, 2, and 3 are mononuclear, the pyrrolide anion shows an η1(N)‐coordination to the metal cation. Complex 4 is also mononuclear, but with an unsymmetric η5‐side‐on‐coordination of the pyrrolide anion to the rubidium cation. In complex 6 two pyrrolide anions are bridged by a water molecule via hydrogen bonds and both pyrrolide anions are coordinated to cesium ions. Compounds 7 and 8 have a salt‐like structure with a sandwich‐like [Rb(15‐crown‐5)2]+ cation and an uncoordinated pyrrolide anion (7) or an uncoordinated hydrogen‐dipyrrolide anion (8).

Coordination complexes of bivalent ansa-ytterbocenes: synthesis, structure and comparison with related unbridged ytterbocenes and ansa-ferrocenes

The dimethylsilyl bridged bis(cyclopentadienide) ligands, {[2,4-(Me3C)2C5H2]2SiMe2}2− and {[(Me3Si)2C5H2]2SiMe2}2−, have been prepared and used for the preparation of ansa-metallocene derivatives of iron and bivalent ytterbium metallocene adducts. The structures of two ansa-ferrocenes, as well as that of the free tetraene [2,4-(Me3C)2C5H3]2SiMe2, have been determined by X-ray crystallography; the lability of the Me3Si group leads to a different ring substitution pattern in the structure of ansa-{[3,4-(Me3Si)2C5H2]2SiMe2}Fe compared with that in ansa-{[2,4-(Me3C)2C5H2]2SiMe2}Fe. The structures of ansa-{[2,4-(Me3C)2C5H2]2SiMe2}Yb(OEt2) and an analogous ansa-ytterbocene isocyanide complex are also reported, and compared with those of non-bridged ytterbocene diethyl ether complexes. Short distances from the ytterbium atom to the diethyl ether β carbon atoms are observed in several structures, consistent with the tendency of ytterbium to maximise its coordination number. Spectroscopic properties for the ansa-ytterbocene etherates and the isocyanide complex are reported and compared with the corresponding adducts of non-bridged ytterbocenes. The reduced Cp(centroid)–metal–Cp(centroid) angle enforced by the ansa-bridge does not lead to significant changes in the optical spectra compared with unbridged metallocene diethyl ether and tetrahydrofuran adducts, but significant changes are observed in the isocyanide adducts; a model rationalising the red and blue shifts of λmax is proposed.

Organoaluminium and -gallium Lewis-Acid Adducts of Tetramethylmethylenediamine

Abstract The compounds Me3Al-Me2NCH2NMe2-AlMe3 (1) and Me3Ga-Me2NCH2NMe2-GaMe3 (2) were prepared by reacting Me2NCH2NMe2 (TMMDA) with two equivalents of the metal trialkyls in hydrocarbon solutions.With the ether adduct Me3Ga·OEt2 Me2NCH2NMe2 reacts to give the monoadduct Me2NCH2NMe2-GaMe3 (3). These compounds were characterized by NMR spectroscopy (1H, 13C and 27Al) and by elemental analyses. Crystal structure investigations show 1 and 2 to be monomeric and to a adopt a trans,trans-conformation for their M-N-C-N-M backbones. 3 is also monomeric in the solid state, but adopts a cis,trans-conformation. Tetramethylformamidinium chloride and also chlorotetramethylformamidinium chloride reacts with lithium aluminium hydride to give the mono-adduct [Me2NCH2NMe2-AlH3]2 (4), which is dimeric and can be regarded as a double TMMDA adduct to Al2H6 with five-coordinate Al atoms. Ab initio calculations on the MP2/6- 311G** level of theory have been performed for the model compound H3N-H2Al(μ-H)2AlH2-NH3 to obtain its molecular structure and vibrational spectrum for comparison with 4 and for the assignment of its vibrational spectrum.

Selective coupling of methylene groups at a Rh/Os core, yielding C2, C3, or C4 fragments: roles of the adjacent metals in carbon-carbon bond formation.

The mixed-metal complex, [RhOs(CO)(4)(dppm)(2)][BF(4)] (1; dppm = micro-Ph(2)PCH(2)PPh(2)) reacts with diazomethane to yield a number of products resulting from methylene incorporation into the bimetallic core. At -80 degrees C the reaction between 1 and CH(2)N(2) yields the methylene-bridged [RhOs(CO)(3)(micro-CH(2))(micro-CO)(dppm)(2)][BF(4)] (2), which reacts further at ambient temperature to give the allyl methyl species, [RhOs(eta(1)-C(3)H(5))(CH(3))(CO)(3)(dppm)(2)][BF(4)] (4). At intermediate temperatures compounds 1 and 2 react with diazomethane to yield the butanediyl complex [RhOs(C(4)H(8))(CO)(3)(dppm)(2)][BF(4)] (3) by the incorporation and coupling of four methylene units. Compound 2 is proposed to be an intermediate in the formation of 3 and 4 from 1 and on the basis of labeling studies a mechanism has been proposed in which sequential insertions of diazomethane-generated methylene fragments into the Rh-C bond of bridging hydrocarbyl fragments occur. Reaction of the tricarbonyl species, [RhOs(CO)(3)(micro-CH(2))(dppm)(2)][BF(4)] with diazomethane over a range of temperatures generates the ethylene complex [RhOs(eta(2)-C(2)H(4))(CO)(3)(dppm)(2)][BF(4)] (7a), but no further incorporation of methylene groups is observed. This observation suggests that carbonyl loss in the formation of the above allyl and butanediyl species only occurs after incorporation of the third methylene fragment. Attempts to generate C(2)-bridged species by the reaction of 1 with ethylene gave no reaction, however, in the presence of trimethylamine oxide the ethylene adducts [RhOs(eta(2)-C(2)H(4))(CO)(3)(dppm)(2)][BF(4)] (7b; an isomer of 7a) and [RhOs(eta(2)-C(2)H(4))(2)(CO)(2)(dppm)(2)][BF(4)] (8) were obtained. The relationship of the above products to the selective coupling of methylene groups, and the roles of the different metals are discussed.