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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.

The lithiacarborane [Li-CB11 H11 ]- plays a central role in carborane chemistry, as it is a key intermediate to achieve the selective functionalization of the monocarba-closo-dodecaborate [CB11 H12 ]- for applications in various fields. Also, it is an organometallic species of fundamental interest because it represents a 3D analogue of phenyllithium featuring an exo C-Li bond in addition to the delocalized negative endo charge of the spherical cluster. For the first time, the elusive and highly reactive endo/exo formal dianion [CB11 H11 ]2- has been isolated as its lithiate as well as zincate in pure form and fully characterized. DFT calculations corroborate the experimental findings and underscore the remarkably high reactivity of the lithiacarborane. Subsequent derivatizations demonstrate the relevance of its initial clean formation.

An anodic stripping voltammetry (ASV) sensing platform which provides real time determination of zincate diffusion through membrane separators in alkaline electrolyte with total experimental times on the order of hours is presented. Advanced separators are essential for future rechargeable alkaline zinc batteries. In order to be screened, these membranes need to be evaluated for their zincate blocking performance. Current complexometric titration and elemental analysis methods for zincate membrane diffusion characterization can take days to weeks to obtain results as well as include large sample dilution factors and require additional sample processing. The anodic stripping voltammetry (ASV) sensing platform presented here provides real time determination of zincate diffusion in alkaline electrolyte with total experimental times on the order of hours. This method eliminates the need for sample dilution and post experiment sample processing. This technique significantly increases the throughput for the screening of advanced alkaline battery separators resulting in rapid turnaround times in the analysis of these vital membranes. To evaluate the utility of this method, zincate diffusion through commercial Celgard 3501 and Cellophane 350P00 was monitored using both ASV and inductively coupled plasma-mass spectrometry (ICP-MS) methods. The obtained zincate diffusion coefficients for both techniques were found to compare favorably.

Several studies have focused on rechargeable zinc–air batteries. Among them, the formation of zincate ions has been studied to enhance the reversibility of the zinc anode. In this study, zinc compounds, such as zinc oxide, chloride, and acetate, showed different solubility in KOH; this is related to the generation of zincate ions. A full-cell test was carried out to compare the electrochemical properties of electrodes. Zinc oxide has a high second discharge capacity of 178 mAh/g. To increase the solubility, the particle size of microsized ZnO was changed to nanosized ZnO. In addition, in the full-cell test, nanosized ZnO showed a higher cycle capacity than microsized ZnO. The reduction peaks were indicated clearly until 10 cycles in the three-electrochemical cell. Therefore, it is essential that microsized ZnO be converted easily to zincate ions.

The one-pot reactions between anhydrous zinc acetate, diethyl or di-n-propyl sulfite, and tetraalkylammonium iodide (120 °C, 12 h) proceed through sulfur-centered Arbuzov-type rearrangement to afford [R1 4N]2[Zn(OSO2R)4] [R1, R = Et (1); R1 = nBu, R = nPr (2)] bearing alkanesulfonate groups bound to the metal center. The zincate salts 1 and 2 are used as precursors for the synthesis of neutral and cationic coordination complexes, namely, [Zn(OSO2Et)2(bipy)(dmso)2] (3; bipy = 4,4'-bipyridine, dmso = dimethyl sulfoxide), [Zn(OSO2nPr)2(bipy)2]·dmso·H2O (4), [Zn(bipy)(H2O)4](OSO2Et)2 (5), [Zn(H2O)6](OSO2Et)2 (6), and [Zn(H2O)6](OSO2nPr)2 (7). X-ray crystallographic studies of 3-7 reveal that the alkanesulfonate groups act as prolific H-bond acceptors and assist the transformation of zero-, one-, or two-dimensional coordination frameworks into three-dimensional structural motifs.

Herein, we report on the synthesis, isolation and comprehensive characterization (M.p., ATR-IR/Raman, elemental analysis, 14N NMR) of tetraazido zincate anions [Zn(N3)4]2− in a series of [Ph4P]+ and [PNP]+ (PNP = bis(triphenylphosphine)iminium) salts. The phase polymorphism in [Ph4P]2[Zn(N3)4] was investigated by temperature dependent Raman, powder and single crystal X-ray diffraction experiments, which indicate the occurrence of five room-temperature stable, and one common high-temperature phase, besides two polymorphs of the acetonitrile solvate [Ph4P]2[Zn(N3)4] · MeCN. Moreover, the synthesis of zinc azide solvates Zn(N3)2 · n solvent (solvent = DMSO, n = 1, 3/2, 3; MeCN, n = 2/3) is presented for the first time. Single crystal X-ray structures of all new compounds were determined. For a better understanding of structure and bonding in E(N3)2, [E(N3)3]− and [E(N3)4]2− (E = Zn, Cd, Hg), theoretical calculations at the M06-2X/aug-cc-pVDZ level were carried out.

International audience

Transient liquid phase bonding (TLP) on AA 6082 samples were performed under ambient non-vacuum conditions, which was possible by a suitable pre-treatment. This treatment involves a zincate treatment followed by copper plating, which is a common industrial process and can be performed in large batches. This treatment allows to remove the natural aluminium oxide layer and to protect the aluminium surface from excessive oxidation. Different bonding conditions were investigated and showed the feasibility of the transient liquid phase bonding process for AA 6082. Energy dispersive X-ray spectroscopy (EDX) investigations showed that the isothermal solidification is already terminated after 5 min. The microstructure of the bonding zone showed no metallurgical discontinuity such as eutectic microstructure or intermetallic Al–Cu phases. However the microstructure shows numerous voids with a size of approximately 30 µm in the bonding zone. It is assumed that these voids were formed during the bonding process due to solidification shrinkage and the presence of interfacial oxide layers. The transient liquid phase bonded samples that were mechanically tested under tensile load showed an average strength of approximately 270 MPa, the minimum yield strength required for the base material according to EN 754-2 is 255 MPa. Due to the notch effect of the voids, the tensile sample failed under forced fracture and showed no plastic deformation. Durch eine geeignete Vorbehandlung konnte das transiente Flussigphasenfugen an der Aluminiumlegierung AA 6082 unter vakuumfreien Umgebungsbedingungen ermoglicht werden. Die Vorbehandlung umfasst eine Zinkatbehandlung der Aluminiumoberflache und die anschliessende Verkupferung der Zinkschicht. Diese Vorbehandlung ist ein bekannter industrieller Prozess, welcher in grosen Chargen durchgefuhrt werden kann. Die Vorbehandlung entfernt die naturliche Aluminiumoxidschicht und schutzt die Aluminiumoberflache vor ubermassiger Oxidation. Anhand der Untersuchung verschiedener Fugeparameter konnte die Machbarkeit des Fugeverfahrens fur die Aluminiumlegierung AA 6082 bestatigt werden. Mittels energiedispersiver Rontgenspektroskopie konnte gezeigt werden, dass die isotherme Erstarrung bereits nach 5 min abgeschlossen war. Die Mikrostruktur der Fugezone war frei von metallurgischen Abweichungen, wie zum Beispiel einer eutektischen Mikrostruktur oder intermetallischen Al–Cu-Phasen. Allerdings zeigte die Mikrostruktur der Fugezone zahlreiche Poren mit einer Grosse von etwa 30 µm. Es wird davon ausgegangen, dass diese Poren durch den Erstarrungsschwund und der Anwesenheit von Oxidschichten an der Grenzflache wahrend des Fugeprozesses entstanden sind. Fugeproben zeigten im Zugversuch eine Festigkeit von 270 MPa, die minimal zu erreichende Streckgrenze fur die Legierung AA6082 betragt gemass EN 754-2 255 MPa. Aufgrund der Kerbwirkung der Poren versagten die Zugproben jedoch mittels Sprodbruch und zeigten eine sehr geringe Plastizitat.

Single crystals of Li4[Zn(NH2)4](NH2)2 were obtained from Li and Zn under ammonothermal conditions (723 K and 1.58 kbar). Li4[Zn(NH2)4](NH2)2 (C2221, a = 5.0005(3) A, b = 15.5410(8) A, c = 10.0712(5) A, Z = 4) represents a new possible intermediate in a conceivable ammonothermal synthesis of the semiconductor Zn3N2. Single crystal X-ray diffraction results, thermal analysis, Raman and IR spectra of tetralithium tetraamido zincate diamide are provided and discussed. Crystal structure data justify a description as CaF2 superstructure variant. Large distances in the crystal structure as well as the intensity and half-width of the bands in Raman and IR spectra indicate the absence of significant hydrogen bonds. Upon heating Li4[Zn(NH2)4](NH2)2 decomposes via intermediate formation of LiZnN, LiNH2 and Li2(NH) to finally provide pure Zn.

Coordination in supramolecular assemblies in aqueous HCl solutions was investigated by reacting alkaline-earth cations (AE2+) and inverted cucurbit[6]uril (iQ[6]) in the presence of the structure-directing agent, tetrachloride zincate ion. Single-crystal X-ray diffraction analysis revealed that the iQ[6]–Mg2+–[ZnCl4]2––HCl interaction system yielded a supramolecular assembly of iQ[6] and [ZnCl4]2– without forming coordination complexes of Mg2+ or Zn2+ with iQ[6]. In contrast, interaction of Ca2+ or Sr2+ with iQ[6] in the presence of [ZnCl4]2– gave rise to linear coordination polymers, which formed a honeycomb-like framework in which the linear polymers occupy cells of the framework. The iQ[6]–Ba2+–[ZnCl4]2––HCl interaction system immediately produced precipitates, thus preventing isolation of single crystals under similar synthetic conditions.

We report a novel catalytic system for the activation of diorganozinc reagents. We assumed that the nucleophilic activation of diethylzinc should be efficiently performed by simple alkali metal salts. Indeed, the combination of sodium salts and 15-crown-5 significantly accelerates the rate of diethylzinc addition to benzaldehyde under mild conditions. The activity of the catalytic system strongly depends on the nature of the anion, decreasing in the order I– > Br– > Cl– > F–. Under the optimized reaction conditions, various aryl, hetero aryl, and aliphatic aldehydes were converted with diethylzinc and the corresponding product was obtained in excellent yields. The first X-ray absorption spectroscopy measurements on such type of reactions provide initial insights that support the proposed catalytic cycle and suggest the formation of a zincate complex.

Regioregular poly(3-hexylthiophene) (P3HT) has been a commonly used p-type semiconducting material for solution processable organic electronics. To establish a living system of “Negishi-type catalyst-transfer polycondensation (NCTP)” using zincate complex as a synthetic method for well-defined P3HT having predictable molecular weight (MW) and low dispersity (Đ), the ligands of Ni catalyst were optimized. As a result, a ligand of 1,2-bis(dicyclohexylphosphino)ethane produced P3HTs with highly controlled number average MWs (1650–32,800) and very low Đ values (1.03–1.17). The polymerization results were strongly influenced by steric hindrance based on the factors of cone angle and bite angle of Ni catalysts, and/or electron-donating ability of phosphine ligands. In addition, we succeeded in the two-stage polymerization of P3HT and the synthesis of P3HT-b-poly(3-octadecylthiophene), the latter of which is the first demonstration by NCTP using zincate complex. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2287–2296

In this article, we report a novel but simple method for the phase transformation of ZnO 2 to flower-like ZnO microstructures hydrothermally at 90°C with and without the assistance of hexadecylamine as surfactant. The generation of zincate ion Zno 2 2-as a growth unit from the reaction between ZnO 2 and peroxide ion O 2 2-in situ plays a key role in the phase transformation of ZnO 2 to ZnO. The morphology, structure, and composition of the products have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDX). It has been demonstrated that the as-fabricated ZnO flowers are composed of self-assembled brooms and rods in the presence and absence of hexadecylamine respectively. On the basis of experimental results, a possible reaction mechanism and the growth processes involved in the formation of flower-like ZnO microstructures are discussed. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Substrate control in target-oriented synthesis is generally important in establishing the required stereogenic center rather than reagent control. During the course of the total synthesis toward Gibberellin A3 (1), a model compound (21) as the A-ring of 1 was accomplished in five overall steps with an overall yield of 15 %, starting from furfural through conjugate addition of lithium trimethylzincate to oxabicyclo[2.2.1]heptadienedicarboxylic ester (2) as the key step. Relative to more common lithium dimethylcuprate or aluminum reagents, this zincate complex showed a complete selectivity with higher reactivity than with other simple enone compounds. The incoming methyl group was 100 % selective from the ring oxygen side of 2, and the enolate intermediate can be protonated stereoselectivly without the bridge-oxygen-ring opening.

An etheric Negishi coupling: The first cross-coupling reaction between aryl alkyl ethers and dianion-type zincate reagents to afford biaryl compounds through selective cleavage of the etheric C(sp(2))-O bond was developed. Dianion-type zincates showed excellent reactivity toward the aromatic ethers under mild conditions, with good functional group compatibility (see scheme).

Metalation has served well for over 80 years as a vehicle for transforming inert C[BOND]H bonds in organic compounds to reactive C[BOND]metal bonds.1 Progress in metalation was accelerated greatly by the development of DoM (directed ortho-metalation),2 pioneered by Snieckus, Beak, and others, a special type of lithiation (aromatic C[BOND]H to Cδ−[BOND]Liδ+) reliant on the high polarity of carbon–lithium bonds in organolithium reagents. Many other metals could not engage in metalation due to the lower polarity/lower reactivity of their corresponding carbon–metal bonds. However, this obstacle has now been cleared by the recognition that when part of a mixed-metal system or other multicomponent mixture, these metals (for example, magnesium, zinc, aluminum or manganese) can exhibit greatly enhanced metalating properties often superior in terms of functional-group compatibility or reaction conditions to that of lithium. Interest in these new “low polarity” metalating agents is widespread with coverage in fundamental chemistry journals,3 process chemistry journals,4 interdisciplinary science journals,5 and in news items in scientific media.6 Knochel’s turbo-Grignard reagents (e.g., (iPr)MgCl⋅LiCl) 7 are examples that have been commercialized. A spectacular demonstration of the special reactivity of bimetallic bases came with the α-zincation of tetrahydrofuran (THF) by the sodium dialkyl(amido)zincate [(TMEDA)Na(μ-TMP)(μ-CH2SiMe3)Zn(CH2SiMe3)] (TMEDA=N,N,N′,N′-tetramethylethylenediamine; TMP=2,2,6,6-tetramethylpiperidine) to produce [(TMEDA)Na(μ-TMP)(μ-OC4H7)Zn(CH2SiMe3)].5 Conventional metalation of THF invariably initiates decomposition by ring opening,8 but in this low-polarity zincation the 5-atom ring of the sensitive α-deprotonated THF anion remains intact. However, this reaction is extremely slow (best yield was 52.7 % after 2 weeks) and requires a massive stoichiometric excess of the cyclic ether (i.e., carried out in neat THF solvent). Here we report a vastly superior methodology to the cyclic THF α-anion, mediated by a lithium aluminate base with a higher amido content than the alkyl-rich zincate reagent. An analogous reaction with the sulfur analogue, tetrahydrothiophene (THTP), is also reported.

International audience; Homoleptic lithium tri- and tetraalkyl zincates were reacted with a set of bromopyridines. Efficient and chemoselective bromine-metal exchanges were realized at room temperature with a substoichiometric amount of nBu4ZnLi2*TMEDA reagent (1/3 equiv; TMEDA=N,N,N',N'-tetramethylethylenediamine). This reactivity contrasted with that of tBu4ZnLi2*TMEDA, which was inefficient below one equivalent. DFT calculations allowed us to rationalize the formation of N***Li stabilized polypyridyl zincates in the reaction. The one-pot difunctionalization of dibromopyridines was also realized using the reagent stoichiometrically. The direct creation of C Zn bonds in bromopyridines enabled us to perform efficient Negishi-type cross-couplings.

The effects of zinc oxide and/or polyethylene glycol (PEG) as electrolyte additives on the corrosion and electrochemical performances of pure aluminum in 4.0?M KOH solutions were investigated by means of hydrogen collection, polarization curve, galvanostatic discharge, scanning electron microscopy (SEM), and energy dispersive analysis of X-ray (EDAX). The addition of ZnO markedly inhibited the corrosion of aluminum in 4.0?M KOH solutions, resulting from the deposition of zinc with high hydrogen evolution overpotential in aluminum surfaces. The introduction of PEG in the alkaline zincate solution obviously improved the deposition of zinc by increase in the overpotential of zinc deposition, thus the corrosion rate of aluminum in the alkaline zincate solutions with PEG was further decreased. The enhancement effect of PEG on the inhibition of zinc oxide first increased and then decreased with increasing the content of PEG in the electrolyte. The electrolyte system with 0.2?M ZnO and 2.0?mM PEG presented the highest inhibition efficiency (98.8%) for the corrosion of aluminum. The results of galvanostatic discharge indicated that the aluminum anode shows excellent discharge performances in the 4.0?M KOH solution with 0.2?M ZnO and 2.0?mM PEG.

A new device for performing electrochemical experiments under automatic change or control of the solution pH was developed. The electrochemical cell consists of a thermostatted glass cell, counter electrode, reference electrode and working electrode, pH sensor, stirrer and gas purging system. A control box and a potentiostat equipped with a frequency response analyser form the electronic equipment, while a piston buret allows dosing the solution of interest e.g. a sodium hydroxide solution. Various modes are available for scanning the pH range or keeping the pH constant if a hydroxide consuming reaction shall be observed at a constant pH value, all during electrochemical experiments are performed. Two application examples are given to demonstrate the versatility of the impedance titrator. One addresses the determination of the breakdown pH value of anodised aluminium and the other quantifies the consumption of zinc during transient formation of zincate precipitates.

Toluene has been directly zincated by reaction with the heteroleptic sodium zincate [(tmeda)Na(tBu)(tmp)Zn(tBu)] (1) to afford a statistical mixture of the meta and para regioisomers of [(tmeda)Na(C(6)H(4)Me)(tmp)Zn(tBu)] (2) (TMEDA = N,N,N',N'-tetramethylethylenediamine, TMP = 2,2,6,6-tetramethylpiperidide). Interestingly, the methyl group of toluene has been left untouched by the mixed-metal base. The crystal structures of both regioisomers have been elucidated by using X-ray crystallography, which revealed a common motif, in which zinc lies in the same plane as the tolyl ring and binds strongly to the carbon that has experienced the deprotonation, leading to a covalent sigma bond; whereas sodium adopts a perpendicular disposition, pi-engaging with the aromatic ring. DFT studies of the reaction of 1 with toluene showed that of the four possible regioisomers, the experimentally observed meta and para ones are the most thermodynamically preferred products due to a large extent to the combined (synergic) effect of the zinc and sodium and the different way in which each metal binds to the tolyl anion. In contrast, the more straightforward benzyl-based zincate [(tmeda)(2)Na(CH(2)Ph)Zn(tBu)(2)] (3) is obtained through an indirect route, in which toluene is first laterally metallated by monometallic butylsodium to afford benzylsodium, which then forms a mixed-metal compound by co-complexation with tBu(2)Zn. Zincate 3 has been characterised by X-ray crystallography in the solid state and by NMR spectroscopy in deuterated THF solution.

A conventional vulcanization system containing tetrabutylammonium bis(4-methylphenyldithiocarbimato)zincate(II) (ZNIBU) was used for curing of natural rubber (NR) compounds. Rheometric (ts1, t90, and CRI) and mechanical properties, such as tensile and tear strengths and modulus at 300%, were measured to evaluate the acceleration potential of ZNIBU. Commercial accelerators (TMTD, MBTS, and CBS) and a binary system CBS/ZNIBU were also tested for comparison purposes. It was observed that ZNIBU alone does not give either safe scorch time or cure rates appropriate for industrial applications. Nevertheless, mechanical properties are comparable to those given by the other accelerators used. As for the binary system, positive synergistic effects can be found in tear strength and modulus of NR vulcanizates. Besides, ZNIBU does not contribute for the formation of nitrosamines in the vulcanization process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A new complex of Zinc(II) and guanidinium pyridine–2,6–dicarboxylate proton transfer compound, (GnH)2 (pydc), was synthesized and characterized using IR, 1H NMR and 13C NMR spectroscopy and single crystal X–ray diffraction. The chemical formula and space group of the resulting complex is (GnH)[Zn(pydc)(pydcH)] · (pydcH2) · 4H2O, P 1 where the final R value is 0.0310 for 13287 reflections collected. The [Zn(pydc)(pydcH)]– anions and the (GnH)+ counter-cations form a three-dimensional solid-state structure by a variety of noncovalent interactions such as ion pairing, hydrogen bonding and π–π stacking which are going to be discussed. (© 2007 WILEY -VCH Verlag GmbH & Co. KGaA, Weinheim)

In the presence of organolithium bases phenyl dialkylcarbamates have previously been shown to undergo facile rearrangement to yield the corresponding salicylamides. However, heterometallic lithium diethyl(2,2,6,6-tetramethylpiperidido)zincate achieves the clean directed ortho-metallation (DoM) of phenyl dialkylcarbamates, with [C6H4{OC(O)NMe2}{Zn(-TMP)Et}Li]2 having been structurally characterized. DFT studies point to a stepwise deprotonative mechanism in which the zincate reagent exhibits kinetic amido basicity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

ZnO crystals were synthesized from basic aqueous solutions including zincate ions stabilized with triethanolamine (N(C2H4OH)3, teaH3) by heating at 60°C. The influence of the basicity of the solutions on the morphology of the ZnO crystals was examined. The aqueous solutions were prepared using ZnSO4·7H2O, N(CH3)4OH (TMAOH), and teaH3 as a zinc source, a base, and a stabilizer, respectively, at a zinc concentration of 0.2 M at a teaH3 / Zn molar ratio of 4. Clear solutions were obtained at a molar ratio of TMAOH / Zn ≥ 3.0. When the clear solutions, in which glass or polyester substrates were placed, were heated at 60°C, agglomerates of ZnO crystals were deposited on the substrates in the TMAOH / Zn range from 3.0 to 3.6. With increasing the TMAOH / Zn ratio, the shape of the resulting ZnO crystals changed from a short asymmetric column with a hexagonal flat edge and a rounded one, through a rocket-like shape formed by intergrowth, to a hexagonal rod. Although no films of ZnO were formed, ZnO crystals with different shapes were synthesized. When the glass substrates pre-coated with a ZnO thin film by a sol-gel method were used, highly oriented, dense ZnO films were formed. The films consisted of rod-like crystals aligned normal to the substrate surface. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The size- and morphology-controlled growth of ZnO nanowire (NW) arrays is potentially of interest for the design of advanced catalysts and nanodevices. By adjusting the reaction temperature, shelled structures of ZnO made of bunched ZnO NW arrays are prepared, grown out of metallic Zn microspheres through a wet-chemical route in a closed Teflon reactor. In this process, ZnO NWs are nucleated and subsequently grown into NWs on the surfaces of the microspheres as well as in strong alkali solution under the condition of the pre-existence of zincate (ZnO22-) ions. At a higher temperature (200 degrees C), three different types of bunched ZnO NW or sub-micrometer rodlike (SMR) aggregates are observed. At room temperature, however, the bunched ZnO NW arrays are found only to occur on the Zn microsphere surface, while double-pyramid-shaped or rhombus-shaped ZnO particles are formed in solution. The ZnO NWs exhibit an ultrathin structure with a length of ca. 500 nm and a diameter of ca. 10 nm. The phenomenon may be well understood by the temperature-dependent growth process involved in different nucleation sources. A growth mechanism has been proposed in which the degree of ZnO(2)(2-)saturation in the reaction solution plays a key role in controlling the nucleation and growth of the ZnO NWs or SMRs as well as in oxidizing the metallic Zn microspheres. Based on this consideration, ultrathin ZnO NW cluster arrays on the Zn microspheres are successfully obtained. Raman spectroscopy and photoluminescence measurements of the ultrathin ZnO NW cluster arrays have also been performed.

Single crystals of methylammonium tetrachloro zincate (II) monohydrate were grown by slow evaporation of saturated aqueous solutions at room temperature. The grown crystals were colourless, bright and transparent. The crystals were characterized through elemental analysis, powder X-ray diffraction, thermogravimetric (TG-DTA) and low temperature differential scanning calorimetric (DSC) techniques. While the powder XRD pattern shows the crystallinity of the compound, the elemental analysis and the TG-DTA confirm the stoichiometry of the compound. The low temperature DSC indicates first order structural phase transition at -8°C during heating cycle. The FTIR and far IR spectra of the compound show characteristic vibrational frequencies due to CH3NH3 and ZnCl42- ions and other chemical bonds. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The predator meets its prey in the structure of [{(iPr)2NC(Ph)(O)}Li(μ-tmp)(μ-tBu)Zn(tBu)] which reveals an aromatic amide–alkali metal zincate “precomplex” for directed ortho-metalation (DoM) that exists prior to the devouring (ortho-zincation) of the amide by the zincate. tmp=2,2,6,6-tetramethylpiperidide.

A room temperature reaction of zinc acetate, tributyl borate and N, N, N′N′-tetramethylethylenediamine (tmen) in a mixture of water and 1-butanol has given rise to a new bis-(hexaborato)-zincate, [(Me)2NH(CH2)2NH(Me)2][{Zn(B6O7(OH)6}2]·2H2O (I). The structure, determined by single crystal X-ray diffraction, (P1, a = 8.3014(2), b = 9.2489(2), c = 10.442(2)A, α = 107.71(3), β = 94.22(3), γ = 100.02(3)°, V = 749.6(3)A3 =Z = 1, R1 = 0.0387, wR2 = 0.105), consists of anionic molecular Zn hexaborate units forming a herringbone arrangement, through strong hydrogen bond interactions, with the amine molecule situated between the chains. Compound I is the first bis-(hexaborato)-zincate, to our knowledge, that has been synthesized in the presence of an organic amine. Losungsvermittelte Synthese und Struktur des ersten in Gegenwart eines organischen Amins praparierten anionischen Bis-(hexaborato)-zinkats Die Reaktion von Zinkacetat, Tributylborat und N, N, N′N′-Tetramethylethylendiamin (tmen) in einer Wasser-/1-Butanol-Mischung bei Raumtemperatur ergab ein neues Bis-(hexaborato)-zinkat, [(Me)2NH(CH2)2NH(Me)2][{Zn(B6O7(OH)6}2]·2H2O (I). Nach Einkristallrontgenstrukturanalyse (P1, a = 8.3014(2), b = 9.2489(2), c = 10.442(2)A, α = 107.71(3), β = 94.22(3), γ = 100.02(3)°, V = 749.6(3)A3 =Z = 1, R1 = 0.0387, wR2 = 0.105) besteht die Kristallstruktur aus anionischen, molekularen Bis-(hexaborato)-zinkat-Einheiten, die uber starke Wasserstoffbrucken zu fischgratenmusterartigen Strangen verbunden sind. Die Aminmolekule liegen zwischen den Ketten. Die Verbindung I ist unseres Wissens das erste Zinkhexaborat, welches in Anwesenheit eines organischen Amins synthetisiert wurde.

We report a novel catalytic system for the activation of diorganozinc reagents. We assumed that the nucleophilic activation of diethylzinc should be efficiently performed by simple alkali metal salts. Indeed, the combination of sodium salts and 15-crown-5 significantly accelerates the rate of diethylzinc addition to benzaldehyde under mild conditions. The activity of the catalytic system strongly depends on the nature of the anion, decreasing in the order I– > Br– > Cl– > F–. Under the optimized reaction conditions, various aryl, hetero aryl, and aliphatic aldehydes were converted with diethylzinc and the corresponding product was obtained in excellent yields. The first X-ray absorption spectroscopy measurements on such type of reactions provide initial insights that support the proposed catalytic cycle and suggest the formation of a zincate complex.

Well-defined poly(2,5-dihexyloxyphenylene-1,4-diyl) (PPP) is successfully synthesized by the Negishi catalyst-transfer polycondensation (NCTP) using dilithium tetra(tert-butyl)zincate (t Bu4 ZnLi2 ). The obtained PPP possesses the number-averaged molecular weight (Mn ) values in the range of 2100-22 000 and the molar-mass dispersity (ÐM ) values in the range of 1.09-1.23. In addition, block copolymers containing PPP and poly(3-hexylthiophene) (P3HT) segments (PPP-b-P3HT) are synthesized to confirm the feasibility of chain extension between the different monomers based on NCTP.

The sequential reaction of ZnMe2 with a 2-pyridylamine (HN(2-C5H4N)R, R = Ph: 1; 3,5-Xy (=3,5-xylyl): 2; 2,6-Xy: 3; Bz (=benzyl): 4; Me: 5), tBuLi and thereafter with oxygen affords various lithium zincate species, the solid-state structures of which reveal a diversity of oxo-capture modes. Amine 1 reacts to give both dimeric THF [Li(Me)OZn[N(2-C5H4N)Ph]2] (6), wherein oxygen has inserted into the Zn-C bond of a [MeZn[N(2-C5H4N)-Ph]2] ion, and the trigonal Li2Zn complex, bis(OtBu)-capped (THF x Li)2-[[(mu3-O)tBu]2Zn[N(2-C5H4N)Ph]2] (7). The structural analogue of 6 (8) results from the employment of 2, while the use of more sterically congested 3 yields a pseudo-cubane dimer [(THF x [Li(tBu)OZn(OtBu)Me]]2] (9) notable for the retention of labile Zn-C(Me). Amines 4 and 5 afford the oxo-encapsulation products [mu4-O)Zn4[(2-C5H4N)-NBz]6] (10b), and [tBu(mu3-O)-Li3(mu6-O)Zn3[(2-C5H4N)NMe]6] (11), respectively, with concomitant oxo-insertion into a Li-C interaction resulting in capping of the fac-isomeric (mu6-O)M3M'3 distorted octahedral core of the latter complex by a tert-butoxide group.

The title compounds were prepared from 1,3,4,6-tetrathiapentalene-2,5-dione (1) in one step via the in situ generated intermediate 2-oxo-1,3-dithiole-4,5-dithiolate (dmid; 2). The X-ray single crystal structure of (Et4N)2[Zn(dmid)2] (3 a) gave the tetragonal space group P43212 with a = b = 13.810(2) A, c = 16.480(3) A, and Z = 4. (n-Bu4N)2[Zn(dmid)2] (3 b) gave the triclinic space group P 1 with a = 11.947(4) A, b = 14.665(5) A, c = 16.662(8) A, α = 100.21(3)°, β = 104.46(3)°, γ = 110.73(3)°, and Z = 2. Synthese und Kristallstrukturen von Bis(tetraethylammonium)(2-oxo-1,3-dithiol-4,5-dithiolato)zinkat(II) und Bis(tetra-n-butylammonium)(2-oxo-1,3-dithiol-4,5-dithiolato)]zinkat(II) Die Titelverbindungen wurden ausgehend von 1,3,4,6-tetrathiapentalene-2,5-dion (1) in einem Schritt uber das in situ erzeugte Zwischenprodukt 2-Oxo-1,3-dithiol-4,5-dithiolat (dmid; 2) hergestellt. Die Einkristallstrukturanalyse von (Et4N)2[Zn(dmid)2] (3 a) ergab die tetragonale Raumgruppe P43212 mit a = b = 13.810(2) A, c = 16.480(3) A, und Z = 4. (n-Bu4N)2[Zn(dmid)2] (3 b) kristallisiert in der triklinen Raumgruppe P 1 mit a = 11.947(4) A, b = 14.665(5) A, c = 16.662(8) A, α = 100.21(3)°, β = 104.46(3)°, γ = 110.73(3)° und Z = 2.

Difluorenylzink (Fluorenyl = Fl) ergibt mit AlCl3 in THF das Komplexsalz [AlCl2(THF)4][ZnCl3(THF)] (1), wahrend die gleiche Reaktion mit GaCl3 zum THF-stabilisierten Gallan [GaFl3(THF)] (2) fuhrt. Aus Umsetzungen mit InCl3 und TlCl3 konnte bisher nur der Komplex [InCl3(THF)3] (3) isoliert werden. Das Losungsmittelgemisch THF/DME liefert den Komplex [InCl3(DME)(THF)] (4). Fur einen Bindungslangenvergleich mit dem Zinkat-Ion [ZnCl3(THF)]− wurde der Komplex [ZnCl2(THF)2] (5) dargestellt. 1-5 wurden mittels NMR- und IR-Spektroskopie untersucht. Von 1, 2 · Toluol, 3 und 5 konnte eine Rontgenstrukturanalyse angefertigt werden. 1 besitzt danach ein Kation mit linearer AlCl2-Einheit und ein Zinkat-Ion, das durch den THF-Liganden nur wenig pyramidalisiert ist. In 2 liegt ebenfalls ein verzerrt tetraedrisch koordiniertes Metall-zentrum vor. Fur 3 wurde eine meridionale Anordnung der THF-Liganden gefunden. In 5 wirkt sich die Abwesenheit einer Ladung im Vergleich zum Zinkat-Ion [ZnCl3THF]− deutlich bindungsverkurzend aus. Difluorenyl Zinc as Alkylation Reagent in Formation of Triorgano Metallanes of Group 13. Synthesis and Crystal Structure of [GaFl3(THF)] · Toluol (Fl = Fluorenyl) Difluorenyl zinc (fluorenyl = Fl) gives with AlCl3 in THF the salt [AlCl2(THF)4][ZnCl3(THF)] (1) while the corresponding reaction with GaCl3 leads to the THF stabilized gallane [GaFl3(THF)] (2). As a result of the reactions of InCl3 and TlCl3 by the mentioned way above only the complex [InCl3(THF)3] (3) could be isolated. The mixture of solvents DME/THF gives the complex [InCl3(DME)(THF)] (4). For a comparison of the binding parameters with the zincate ion [ZnCl3(THF)]− the compound [ZnCl2(THF)2] (5) has been synthesized. 1–5 were characterized by NMR and IR techniques. 1, 2 · toluene, 3 and 5 could also be investigated by X-ray structure analysis. According this, 1 possesses a cation with a linear AlCl2 unit and a zincate ion, which is only sligthly pyramidalisized by the THF ligand. 2 contains also a distorted tetrahedral coordinated metal center. For 3 a meridional arrangement of the THF ligands was found. In 5 the absence of a negative charge leads to a shortening of the bond lengths in comparison to the zincate ion [ZnCl3(THF)]−.

Chemical change of trace zinc in ordinary portland cement (205.1 ppm) was investigated in hydration process using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Intensities of the peaks appearing at the same energy of ZnO in XANES spectra were decreased with cement hydration. The interatomic distances and the coordination numbers of the first and the second shells calculated from EXAFS spectra indicated that ZnO hydrolyzed to zincate ion [Zn(OH)4]2− with cement hydration keeping their fundamental structure of ZnO4 tetrahedra.

Die Verbindungen (dmpipzH2)[MIICl4] kristallisieren monoklin in der Raumgruppe P21/m mit a = 6,133(1), b = 14,306(1), c = 6,902(1) A, β = 90,54(2)°, Z = 2 fur M = Co und mit a = 6,141(1), b = 14,282(1), c = 6,907(1) A, β = 90,60(2)°, Z = 2 fur M = Zn. In den Strukturen liegen Tetraeder [MCl4]2− und zentrosymmetrische (dmpipzH2)2+-Kationen in Sesselform vor. Es werden gabelformige Wasserstoffbruckenbindungen des Typs NH … Cl zu zwei Chloridionen gebildet. Zwei kurze Abstande C … Cl werden als CH … Cl-Wasserstoffbruckenbindungen gedeutet. Halogenometalates of Transition Elements with N-heterocyclic Base Cations. I. The Crystal Structures of 1,4-Dimethylpiperazinium Tetrachlorocobaltate(II) and -zincate(II), (dmpipzH2)[MIICl4] (M = Co, Zn) The compounds (dmpipzH2)[MIICl4] crystallize in the monoclinic space group P21/m with a = 6.133(1), b = 14.306(1), c = 6.902(1) A, β = 90.54(2)°, Z = 2 for M = Co and with a = 6.141(1), b = 14.282(1), c = 6.907(1) A, β = 90.60(2)°, Z = 2 for M = Zn. The structures consist of tetrahedra [MCl4]2− and centrosymmetric cations (dmpipzH2)2+ in the chair form. Bifurcated hydrogen bridging bonds of the NH … Cl type connect the nitrogen atom to two chloride ions. Two short distances C … Cl are interpreted in terms of CH …Cl hydrogen bridges.

Two new bimetallic approaches for the selective 2,5-dideprotonation and chemoselective room temperature C-H alkylation of pyrazine are presented.

Sulfinylnitriles, e.g. (I), (XII), (XV) or (XVII), smoothly undergo sulfinyl—metal exchange with Grignard reagents, organolithium or lithium zincate reagents to generate the corresponding α-metallated nitriles, which are trapped with various electrophiles.

The direct regioselective zincation is studied and the resulting zinc organics are quenched with iodine or employed in Pd-catalyzed Negishi cross-coupling reactions.

Mit einer Schmelzmitteltechnik wurde erstmals Ba3In2Zn5O11 dargestellt und an Einkristallen rontgenographisch untersucht. Es kristallisiert kubisch, in der Raumgruppe T-F43m, mit a = 13,3588 A und Z = 8. Zn2+ ist tetraedrisch von O2− koordiniert und bildet Zn10O20-Makropolyeder. Ferner wird der nZn/Osol;O-Teil der Kristallstruktur aus Zn10O20-Bausteinen zusammen-gesetzt. Die oktaedrisch koordinierten In3+-Ionen verknupfen uber Kanten zu In4O16–Baugruppen. Die Kristallstruktur wird vorgestellt und diskutiert. On the Crystal Structure of Ba3In2Zn5O11. An Oxoindate/zincatesol;zincate with Zn10O20 and In4O16 Macropolyhedra with Zn2+ in Tetrahedral Coordination by O2− Ba3In2Zn5O11 was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T-F43m, a = 13.3588 A, Z = 8. Zn2+ show tetrahedral coordination by O2−, forming Zn10O20 macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn10O20 parts. Edge connection of four InO6 octahedra results in In4O16 groups. The crystal structure will be shown and discussed.

Transmetalations of zincates succeed only after activation of the barium metal. Dialkylbarium, the initial product, metalates the zincate anions which are still present in solution and leads to the formation of tetraanionic tris(zincate) ligands, which sterically shield the Ba-C bonds of a Ba4 Zn2 C6 cage.

Stereoselective method for preparing a variety of di- and trisubstituted cyclopropanes starting from readily available 1,1-dibromocyclopropanes. It has been demonstrated that the 1,2-alkyl migration reaction of a zincate carbenoids proceeds stereospecifically with inversion of the configuration. By controlling the stereochemistry of a zincate carbenoid, one can obtain the desired stereoisomer of the substituted cyclopropanes in a one pot reaction. Efficiency a well as promising synthetic potential of the cyclopropyl-zinc species in palladium-catalyzed cross-coupling reaction has been demonstrated

Both lithium and zincate carbenoids (R 1 -(R 2 )C=C(Br)M; M=Li and Zn(Bu) 2 Li) generated by the halogen/metal exchange reaction of 1,1-dibromoalkene 1 with BuLi and (Bu) 3 ZnLi, respectively, are configurationally stable at low temperatures, but in the presence of excess 1, the lithium carbenoids undergo facile isomerization at the carbenoid carbons. Under kinetically controlled conditions, both the Br/Li and Br/Zn exchange reactions take place preferentially at the sterically more hindered bromine atom of 1