Zinc Dialkyls Research Articles

The tantalum-catalyzed carbozincation of 1-alkenes with zinc dialkyls

The TaCl5-mediated reaction between monosubstituted alkenes and Et2Zn affords 3-(R-substituted)-n-butylzincs in high yield (up to 92%) and regioselectivity. Organozinc reagents bearing a longer alkyl chain (R = Prn, Bun, Amn, Hexn) react with 1-alkenes in the presence of TaCl5 as the catalyst to give two types of organozinc compound having iso-alkyl structure. The probable mechanism of the carbozincation reaction implies the formation of β-substituted and β,β'-disubstituted tantalacyclopentanes as the key intermediates. The thermodynamic probability of the mechanistic elementary stages for the ethylzincation of terminal alkenes has been estimated using DFT PBE/SBK method.

Abstraction of β-hydrogenvs.alkyl groups in reactions of dialkylzinc compounds and bis(oxazolinyl)borane

An ambiphilic bis(oxazolinyl)borane proligand and zinc dialkyls react via alkyl group transfer or β-hydrogen abstraction. The latter process is favored by formation of a bis(oxazolinyl)borane-zinc adduct that positions a β-hydrogen in the proximity of the Lewis acid center.

Synthesis of Stannyl-Substituted Zn4O4 Cubanes as Single-Source Precursors for Amorphous Tin-Doped ZnO and Zn2SnO4 Nanocrystals and Their Potential for Thin Film Field Effect Transistor Applications

The first heterobimetallic alkyl(trimethylstannoxy)zinc clusters with the formula [Me3SnOZnR]4 (R = Me 1, Et 2) are facile accessible by the Bronsted acid−base reaction of trimethyltin hydroxide with the respective zinc dialkyls ZnR2 (R = Me, Et). The resulting products 1 and 2 can be isolated as white solids in high yields (>95%) and were characterized by multinuclear NMR, elemental analysis, FTIR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction analyses. They proved to serve as unprecedented low-temperature single source precursors (SSPs) for the fabrication of tin-containing ZnO as well as zinc stannate semiconducting materials and could be successfully utilized in field effect transistor (FET) applications. The thermal degradation of 1 and 2 under dry synthetic air, monitored by thermogravimetric analysis (TGA and TGA-IR), indicates high volatility of the trimethylstannyl group, which turned out to be the key parameter to control the tin concentration in the final semiconducting p...

Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics

The reactions of zinc dialkyls, R(2)Zn (1a-d; R = Me (a), Et (b), iPr (c) and tBu (d)), with N,N-dialkylhydroxylamines, HO-NR'(2) (2a-c; R' = Me (a), Et (b) and iPr (c)), afford organozinc hydroxylamides under alkane extrusion. Species of different nuclearity are observed, depending on the hydroxylamine 2 employed. The smaller 2a and 2b give pentanuclear complexes of the general formula Zn(RZn)(4)O-NR'(2))(6) (R = Me, Et, iPr and tBu; R' = Me and Et), whereas the derivatives of 2c are tetramers of the general formula (RZn)(4)(O-NR'(2))(4) (R = Me, Et and iPr; R' = iPr) as governed by bulk issues about the N-donor. Due to the ability of the double-donor unit O-NR(2) to change its bridging mode, two coordination isomers exist for both types of compounds. The pentanuclear species crystallise either in a heterofenestrane or an octahedroid motif. For these species, the central Zn atom exhibits either coordination number 4 or 6; in solution, a rapid change between coordination isomers is observed. Due to the absence of a central Zn atom in the tetranuclear species, these aggregate in heterocubane geometries or such derived thereof. They display the O-N units in either κ(3)O or κ(2)O;κ(1)N mode. The tetranuclear species are also yielded with the less sterically encumbered precursors under thermodynamic conditions (i.e. reflux), as exemplified by the reaction of Me(2)Zn (1a) with HO-NEt(2) (2b). They are non-dynamic in solution, showing that a central cation is mandatory for the fluxional behaviour observed for the pentanuclear derivatives. DFT studies on the O-NMe(2) series reveal that the relative energies of the pentazinc isomers become more similar with increasing RZn group size; possible conversions of these to their tetrazinc counterparts were also scrutinised. Two κ(3)O-bridged degradation products of hydroxylamide complexes could be structurally characterised. They were formed either by partial product hydrolysis, or by in situ oxygenation of the starting zinc dialkyl.

ChemInform Abstract: Theoretical and Experimental Study of Diamagnetic and Paramagnetic Products from Thermal and Light-Induced Alkyl Transfer Between Zinc or Magnesium Dialkyls and 1,4-Diaza-1,3-butadiene Substrates

ChemInform Abstract: Theoretical and Experimental Study of Diamagnetic and Paramagnetic Products from Thermal and Light-Induced Alkyl Transfer Between Zinc or Magnesium Dialkyls and 1,4-Diaza-1,3-butadiene Substrates

Synthesis, Structures, and Ring-Opening Polymerization Reactions of Substituted Cyclopentadienyl Complexes of Zinc

The reaction of 2 equiv of the new pyrrole-substituted cyclopentadienyl ligand cyclo-C4H4NSiMe2C5H5 (2a, CppyH) with Zn[N(SiMe3)2]2 gives the bis(cyclopentadienyl)zinc complex Zn(Cppy)2 (3a). The reaction of 2a and the related derivatives cyclo-2,5-Me2C4H2NSiMe2C5H5 (2b, CppymeH) and 3,5-Me2C6H3CH2CMe2C5H5 (2c, CpmesH) with dibutylmagnesium gives the corresponding magnesocenes MgCpR2 (3a−c). Prolonged heating of the appropriate cyclopentadiene with zinc dialkyls in toluene, or alternatively stirring with [XZnN(SiMe3)2]2 in toluene at 40 °C for 1 h, gives the monocyclopentadienyl zinc alkyl complexes CpRZnX (6a, CpR = Cppy, X = Me; 6c, CpR = Cpmes, X = Me; 7a, CpR = Cppy, X = Et; 7c, CpR = Cpmes, X = Et), which provide spectroscopic evidence for a Zn···(hetero)arene interaction. Addition of tetramethylethylenediamine (TMEDA) gives CpRZnX(TMEDA) (8a, b, X = Me; 9a−c, X = Et). The crystal structures of 8b and 9c show η2-bound cyclopentadienyl ligands, with one long and one short Zn−C interaction. The reactio...

Synthesis of zinc dialkyls from zinc and alkyl bromides

Zinc dialkyls with linear radicals were prepared from zinc and alkyl bromides in the presence of stimulating systems based on a transition metal derivative and an organometallic compound capable of reducing the transition metal derivative under the reaction conditions.

Reactions between primary amines and magnesium or zinc dialkyls: intermediates in metal imide formation

The reactions of several different primary amines with diorganomagnesium or dialkylzinc compounds are reported. Treatment of Mg(η 5-C 5H 5) 2 with t-BuNH 2 or DippNH 2 (Dipp = 2,6- i- Pr 2 C 6 H 3−) leads to the adduct Mg(η 5-C 5H 5)(η 2-C 5H 5) {NH 2(t-Bu)}THF ( 1a) or the amide Mg(η 5-C 5H 5)(NHDipp)THF ( 1b). Reaction between Mg(t-Bu) 2 or commercially available Mg‘Bu’ 2 (‘Bu’ = statistical mixture of n-Bu and s-Bu groups) gave the dimeric amide species [t-BuMg{NH(t-Bu)}THF] 2 ( 2a) or [‘Bu’Mg{NH(t-Bu)}THF] 2 ( 2b). In contrast reaction of Mg‘Bu’ 2 with MesNH 2 or TriphNH 2 (Mes = 2,4,6-Me 3 C 6 H 2−, Triph = 2,4,5-Ph 3C 6H 2−) gave, after suitable workup, the bisamides Mg{(NHMes) 2{OP(NMe 2}) 3} 2 ( 3a) or Mg(NHTriph) 2(THF) 2·THF ( 3b ·THF). A bisamide, the dimer {Mg(NCy 2) 2} 2 ( 4), was isolated in almost quantitative yield by the reaction of dibutylmagnesium with 2 equiv. of HNCy 2 (Cy = cyclohexyl) whereas the trimetallic amide Mg 3(μ-NHDipp) 4N(SiMe 3) 2 2 ( 5) was isolated from the transamination reaction between DippNH 2 and [MgN(SiMe 3) 2 2] 2. A unique product with a rare dodecameric ring structure, (EtMgNHDipp) 12 ( 6), was observed when MgEt 2 reacts with DippNH 2. Reaction between ZnEt 2 or Zn(CH 2SiMe 3) 2 and a variety of primary amines afforded a selection of structurally diverse products. The compounds isolated were: {EtZn(NHPh)THF} 3 (7), {EtZn(NHMes)THF} 2·0.5THF ( 8·0.5THF), Et 2Zn 4(NHDipp) 4(OEt) 2 ( 9), {EtZnNH(t-Bu)} 3 ( 10) and (Me 3SiCH 2ZnNHDipp) 2 ( 11). Crystal data: 1a, a = 10.863(2), b = 9.299(2), c = 17.787(5) A ̊ , β = 98.56(2)° , monoclinic, space group P2 1/ c, Z = 4, R = 0.048 for 2337 ( I>2 σ(1)) data; 2a, a = 8.922(2), b = 16.101(4), c = 11.132(2) A ̊ , β = 111.18(2)° , monoclinic, space group P2 1/ n, Z = 2, R = 0.081 for 2076 ( I>2 σ(1)) data; 3a, a = 11.174(2), b = 18.161(4), c = 18.808(6) A ̊ , β = 92.34(3)° , monoclinic, space group P2 1/ n, Z = 8, R = 0.145 for 4945 ( I>2 σ( I)) data; 4, a = 22.828(5), b = 10.768(2), c = 21.350(4) A ̊ , β = 117.74(3)° , monoclinic, space group P2 1/ c, Z = 4, R = 0.067 for 6264 ( I>2 σ( I)) data; 5, a = 21.754(5), b = 15.214(2), c = 20.657(4) A ̊ , orthorhombic, space group Pbcn, Z = 4, R = 0.063 for 2338 ( I > 2 σ( I)) data; 6, a = 26.063(5), b = 35.332(4), c = 24.535(4) A ̊ , orthorhombic, space group Pnma, Z = 4, R = 0.178 for 10408 ( I > 2 σ( I)) data; 7, a = 12.715; (3), b = 13.606(3), c = 22.339(5) A ̊ , α = 90.53(3) , β = 96.20(3), γ = 93.85(3)°, triclinic, space group P 1, Z = 4, R = 0.143 for 4483 (I > 2σ(I)) data; 8·0.5THF, a = 43.58(2), b = 8.724(2), c = 38.90(1) A ̊ , β = 117.49(2)° ; monoclinic, space group C2/ c, Z = 16, R = 0.058 for 5587 ( I>2 σ( I)) data; 9, a = 10.875(2), b = 11.669(2), c = 11.968(2) A ̊ , α = 76.17(2), β = 86.52(2), γ = 69.69(2)° , triclinic, space group P 1, Z = 1, R = 0.043 for 2733 (I > 2σ(I)) data; 10, a = 11.281(3), b = 14.891(4), c = 15.103(5) A ̊ , β = 90.88(2)° , monoclinic, space group P2 1/ n, Z = 4, R = 0.060 for 2363 ( I>2 σ( I)) data; 11, a = 10.147(2), b = 11.640(2), c = 17.521(2) A ̊ , α = 71.23(1), β = 77.50(1), γ = 69.78(1)° , triclinic, space group P 1, Z = 2, R = 0.065 for 4752 ( I > 2 σ( I)) data.

Multiphoton dissociation of zinc dialkyls probed by resonance-enhanced multiphoton ionization

The production of zinc atoms in multiphoton dissociation of zinc dialkyls is probed via the resonance-enhanced multiphoton ionization technique. Asymmetric power-dependent broadening of resonant line profiles is observed. The dependence of resonant zinc ion yield is analyzed as a function of wavelength and intensity of laser field. Evidence is obtained that the dissociative production of ground state zinc atoms is suppressed with increasing laser intensity.

ChemInform Abstract: Coordination Chemistry of Zinc Dialkyls. Part 18. Synthesis, Properties, and Complex Formation of Bis(1‐camphenyl)zinc.

AbstractThe rigid allyl system in the title compound (III) bonding in a η1‐fashion is confirmed by the characterization of all compounds by IR, electronic, mass and 1H NMR spectroscopy.

On the products of reactions of zinc dialkyls with pyrogallol

Reactions of dialkylzinc compounds ZnR 2 (R  Me, Et) with pyrogallol (PG) have been carried out. The reaction products obtained with mole ratios of reactants 3/1 2/1 and 1/1, respectively, were characterized by means of IR, 1H NMR spectroscopy, elemental analysis and cryometry. The product formed from ZnR 2/PG 2/1 (the best known catalytic system for the alternating CO 2/propylene oxide copolymerization) was found to be 1,3,2-benzodioxazincol-4-alkylzincolate.

A contribution to the chemistry of organotransition metal halides

Transition metal halides are often converted into more or less well-defined reduction products by Grignard reagents. organolithium and organoaluminium compounds. By means of less polar alkylating or arylating agents. such as zinc dialkyls. tin tetraalkyls and boron trialkyls. definite organotransition metal halides can be obtained. Alkyl and aryltitanium trihalides. alkyltungsten pentachlorides and complexes of alkylzirconium trihalides, dialkyizirconium dihalides and dialkylvanadium dichlorides. prepared in this way. are described and discussed. The chemistry of cs-transition metal compounds has been greatly developed in the last 10—15 years. The new compounds of this class of substances are predominantly such in which, besides cs-bonded organo-groups, ligands capable of forming it-bonds, such as carbon monoxide molecules or cyclopentadienyl groups are attached to the metal atoms. In this case, the it-bonded ligands ordinarily cause a rise in the stability of the cs-metal—carbon bonds. According to the kind of reflection, the conditions of the bonds at the transition metal atoms are more simple or more complicated if, except for the cs-bonded alkyl or aryl groups, only halogen atoms are attached to the metal atoms. However, it is not yet possible to give universal statements concerning this part of the chemistry of organotransition metals since the number of known and more precisely characterized organotransition metal halides is still very small. This is still a very undeveloped area of' organometallic chemistry, the treatment of which, however, requires a considerable amount of experimental work. Experiments to alkylate or arylate different transition metal halides were carried out even in the second half of' the last century. Zinc and mercury dialkyls or aryls and Grignard reagents and later organolithium compounds, were used predominantly, as alkylating agents. In many of these experiments the sensitivity of the expected compounds to air and moisture was not sufficiently taken into account. However, more important in all these former experiments was th fact that the small thermal stability of many organotransition metal compounds, which is well known today, was not expected at that time, and therefore, only more or less well-defined reduction products of the transition metal halides were obtained. However, the decomposition temperature of the desired organotransition metal halides

Organozinc coordination chemistry and catalytic effects of organozinc coordination compounds

A review of the present state of organozinc coordination chemistry. with special emphasis on compounds of the type RZnX is given. Their preparation as well as some factors determining their structure and stability are discussed. Certain organozinc coordination compounds have been found to be effective catalysts for cyclo-oligomerization and polymerization reactions. in particular of oxygen-containing monomers (isocyanates, aldehydes. lactones and epoxides). The present views on the mechanisms of these reactions are given. INTRODUCTION Organozinc chemistry is an old subject: it started around 1850 and contributed much to the early development of organometallic chemistry as a whole. Organozinc compounds. in particular the zinc dialkyls. for some decades found extensive laboratory use as alkylating agents. until their replacement around 1900 by the organomagnesium compounds. After having been somewhat dormant for about sixty years—one notable exception being the continuing and even extending use of the Reformatsky reaction— organozinc chemistry towards 1960 entered into its second stage. Partly this was caused by the general renascence of organometallic chemistry as a whole in the early fifties. but it also was due to the discovery by Simmons and Smith in 19581 of the extremely useful zinc-containing organometallic reagent for the generation of carbene. Our own interest in organozinc chemistry reaches back to 1962 when we were invited by the International Lead Zinc Research Organization at New York to start an exploratory programme of organozinc research. Since then we have been actively engaged at Utrecht in the synthesis of organozinc compounds and their use in organic synthesis. but in particular in the study of organozinc coordination chemistry and of the catalytic effects of organozinc coordination compounds. My lecture deals with the two latter aspects of this work. For bivalent zinc two basic types of organozinc compounds must be considered: R2Zn and RZnX. R being hydrocarbon groups or. more generally groups attached to zinc via a zinc—carbon bond. and X being a

Zur darstellung von alkyl-kupfer-verbindungen

Pure copper alkyls may be prepared by reaction of anhydrous copper(II) chloride with zinc dialkyls at low temperature. The preparation of methylcopper, ethylcopper, propylcopper and 1 : 1 complexes of methylcopper with 2,2′-bipyridine and dimethylformamide is described. All these compounds are thermally instable and tend to decompose explosively.

A New Synthesis of Zinc Dialkyls

エチレン, プロピレン, およびその他の α-オレフィンの重合触媒として使用されるジアルキル亜鉛は, 従来, 亜鉛銅合金とヨウ化アルキルとの反応, またはその変形, およびその他の方法 (たとえばジアルキル水銀と亜鉛との反応) により合成されて来た。著者は亜鉛銅合金のかわりに亜鉛-マグネシウム合金を使用し, 目的を達することができた。このように, ある金属とマグネシウムとの合金を使用して, その金属のアルキル化合物をつくる方法は, アルキル亜鉛の合成の目的には, ほとんどその例を見ないが, たとえばトリアルキルアルミニウムのような金属アルキルの合成にはすでによく知られたところである。また, この亜鉛-マグネシウム合金を用いた反応は形式的にはすでによく知られた (1) 式の反応に帰するわけであるが, 一段階の反応で目的物をうることができるので, この点既知の方法とは多少異なるものと思われる。RMgX+RZnX=R2Zn+MgX2 (1) この反応では, まず合金中のマグネシウムがヨウ化アルキルと作用して, グリニャール試薬をつくり, そのため, 活性に富むと思われる新鮮な亜鉛面が露出し, これがただちにヨウ化アルキルと反応して, ヨウ化アルキル亜鉛を形成し, このものはまた, 容易にさきのグリニャール試薬と反応して, 順次ジアルキル亜鉛を与えるものと解釈できる。