Mg In THF Research Articles

Suitability of Carbazolyl Hauser and Turbo‐Hauser Bases as Magnesium‐Based Electrolytes

AbstractLithium‐ion batteries pose certain drawbacks and alternatives are highly demanded. Requirements such as low corrosiveness, electrochemical stability and suitable electrolytes can be met by magnesium‐ion batteries. Metalation of carbazole with Mg in THF in the presence of ethyl bromide yields the sparingly soluble Hauser base [(thf)3Mg(Carb)Br] (1) which shows a Schlenk‐type equilibrium with formation of [(thf)3Mg(Carb)2] and [(thf)4MgBr2]. A THF solution of 1 shows a low over‐potential and a good cyclability of electrodeposition/‐stripping of Mg on a Cu current collector. An improved performance is achieved with the turbo‐Hauser bases [(thf)(Carb)Mg(μ‐Br/X)2Li(thf)2] (X=Br (2) and Cl (3)) which show a significantly higher solubility in ethereal solvents. The THF solvation energies increase from (thf)xMgBr2 over (thf)xMg(Carb)Br to (thf)xMg(Carb)2 for an equal number x of ligated THF molecules.

Synthesis and Characterization of Hypervalent Organoantimony(III) Compounds Containing the [2‐(Me2NCH2)C6H4]2Sb Fragment

AbstractCompounds containing the [2‐(Me2NCH2)C6H4]2Sb moiety were prepared by using R2SbX [X = Cl (1), Br (2)] as starting materials. The reaction of 1 with Me3SiCH2MgCl gave the mixed alkyl–aryl stibine R2SbCH2SiMe3 (3). Reduction of 2 with Mg in thf followed by in situ air oxidation or treatment with S8 resulted in the isolation of (R2Sb)2E [E = O (4), S (5)]. Compound 5 is also formed from R2SbCl and Na2S. The reaction of 4 with [W(CO)5(thf)] gives the unexpected complex [(R2SbOH)W(CO)5] (6). The new compounds were investigated by IR, 1H, and 13C NMR spectroscopy, as well as by mass spectrometry. The structures of 3–6 were determined by single‐crystal X‐ray diffraction. For compounds 3–5, both nitrogen atoms from the pendant arms are involved in intramolecular N→Sb coordination, which results in distorted square‐pyramidal (C,N)2SbC or (C,N)2SbE (E = O, S) cores. By contrast, in 6 only one nitrogen atom is strongly coordinated to the antimony center, whereas the second nitrogen atom is involved in N···H–O bonding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Novel sandwich complexes of zirconium [C 9H 5(SiMe 3) 2](C 5Me 4R)ZrCl 2 (R = CH 3, CH 2CH 2NMe 2): Synthesis and reduction behavior

Novel half-sandwich [C 9H 5(SiMe 3) 2]ZrCl 3 ( 3) and sandwich [C 9H 5(SiMe 3) 2](C 5Me 4R)ZrCl 2 (R = CH 3 ( 1), CH 2CH 2NMe 2 ( 2)) complexes were prepared and characterized. The reduction of 2 by Mg in THF lead to (η 5-C 9H 5(SiMe 3) 2)[η 5:η 2( C, N)-C 5Me 4CH 2CH 2N(Me)CH 2]ZrH ( 7). The structure of 7 was proved by NMR spectroscopy data. Hydrolysis of 2 resulted in the binuclear complex ([C 5Me 4CH 2CH 2NMe 2]ZrCl 2) 2O ( 6). The crystal structures of 1 and 6 were established by X-ray diffraction analysis.

Syntheses and chemistry of hypervalent cyclo-R4Sb4, cyclo-(RSbE)n[R = 2-(Me2NCH2)C6H4, E = O, S] and precursors

The cyclostibane R(4)Sb(4)(1)(R = 2-(Me(2)NCH(2))C(6)H(4)) was synthesized by reduction of RSbCl(2) with Mg in THF or with Na in liquid NH(3). The reaction of 1 with [W(CO)(5)(THF)] gives the stibinidene complex RSb[W(CO)(5)](2)(2). RSbCl(2) and (RSbCl)(2)E [E = O (6), E = S (8)] react with KOH or Na(2)S in toluene/water to give the heterocycles (RSbE)(n)[E = O, n= 3 (3); E = S, n= 2 (4)]. The chalcogeno-bridged compounds of the type (RSbCl)(2)E [E = O (6), E = S (8)] were synthesized by reaction of RSbCl(2) with KOH or Na(2)S in toluene/water, but also by reaction of RSbCl(2) with the heterocycles (RSbE)(n). The compounds (RSbI)(2)O (7) and (RSbBr)(2)S (9) were prepared via halogen-exchange reactions between (RSbCl)(2)E and NaI (E = O) or KBr (E = S) or by reactions between RSbI(2) and KOH or RSbBr(2) and Na(2)S. The reaction of cyclo-(RSbS)(2) with W(CO)(5)(THF) in THF results in trapping of the cis isomer in cyclo-(RSbS)(2)[W(CO)(5)](5). The solution behaviour of the compounds was investigated by (1)H and (13)C NMR spectroscopy. The molecular structures of compounds 1-7 and 9 were determined by single-crystal X-ray diffraction.

Cis‐1‐phosphabicyclo[3.3.0]octan

AbstractA new approach to 1‐phosphabicyclo[3.3.0]octane compounds starts from the reaction of 4‐chloro‐hepta‐1.6‐diene with Mg in THF. No Grignard rearrangement is observed. The Grignard reagent is converted into 1‐allyl‐3‐butenylphosphonous dichloride followed by reduction with LiAlH4. Cis‐1‐phosphabicyclo[3.3.0]octane has been prepared by radical‐initiated cyclization of 1‐allyl‐3‐butenylphosphane. The bicyclic phosphane is characterized by analytical data as well as 31P and 13C NMR measurements and the reactionswith NO, S8, KSeCN, CH3I, Ni(CO)4 and HSO3F, respectively.

Low‐Valent Organobismuth Compounds with Intramolecular Coordination: cyclo‐R3Bi3, cyclo‐R4Bi4, RBi[W(CO)5]2, and R4Bi2 [R = 2‐(Me2NCH2)C6H4

AbstractThe cyclobismuthanes RnBin, [R = 2‐(Me2NCH2)C6H4; n = 3 (1a), 4 (1b)] have been synthesised by reduction of RBiCl2 with Na in liquid NH3 or by reaction of R2BiCl with LiAlH4 in Et2O. The reaction of 1a/b with W(CO)5·THF afforded the bismuthinidene complex RBi[W(CO)5]2 (2). R2BiCl reacts with Mg in THF to give the dibismuthane R4Bi2 (3). Single‐crystal X‐ray structure analyses of 1b, 2, and 3 reveal intramolecular coordination of the pendant CH2NMe2 groups to the bismuth atom. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Activation of the (Trimethylsilyl)tetramethylcyclopentadienyl Ligand in the [C5Me4(SiMe3)]2TiCl2/Mg System, Yielding Intramolecular Si−CH2−Mg and Si−CH2−Ti Bonds. Molecular Structures of {[η5-C5Me4SiMe2(μ-CH2{Mg,Mg})][η5-C5Me4(SiMe3)]TiIII(μ-H)2Mg(THF)}2 and [η5:η1-C5Me4SiMe2CH2][η5-C5Me4(SiMe3)]TiIII

The reduction of [C5Me4(SiMe3)]2TiCl2 by excess Mg in THF yields the paramagnetic compound {[η5-C5Me4SiMe2(μ-CH2{Mg,Mg})][η5-C5Me4(SiMe3)]TiIII(μ-H)2Mg(THF)}2 (3). In the presence of Me3SiC⋮CSiMe3 ...

Syntheses, Structures, and Equilibria of o‐, m‐, p‐Tolyl‐ and Phenylantimony Rings

AbstractExchange reactions of R3Sb (R = o‐Tol, m‐Tol, p‐Tol) with SbCl3 in a 1:2 molar ratio give RSbCl2. Silylstibanes RSb(SiMe3)2 were obtained by reaction of RSbCl2 and Me3SiCl with Mg in THF. Slow access of air to solutions of RSb(SiMe3)2 afforded orange crystals of the composition (RSb)n. Crystal structures were determined by X‐ray crystallography for R = o‐Tol and m‐Tol as stacks of (RSb)6 rings in the chair conformation with equatorial substituents. In the crystals of (m‐TolSb)6 there are short intermolecular Sbb distances of 420 pm. Solutions of (RSb)n (R = Ph, o‐Tol, m‐Tol, p‐Tol) in C6D6 were analyzed by 1H‐NMR spectroscopy. They contain (RSb)5 and (RSb)4 in equilibria. Raman spectra of (PhSb)6 or (p‐TolSb)n show signals for Sbn at β = 151 or 153 cm‐1. 13C‐CP‐MAS‐NMR data of (p‐TolSb)n are reported.

Synthesis and Properties of New Perfluorinated Aliphatic Isocyanides

Although the first fluorinated isocyanide, CF~NEC, was first synthesized in 1967,' synthesis of other fluorine-containing analogues and, in particular, a study of their chemistry has occurred only in more recent years. This chemistry has been recently reviewed.* Known perfluorinated isocyanides include CF3NGC, CsFsNX!,' SF5NsC.4 and CF2=CFN=C5 a-Dehalogenation of the corresponding dibromomethanimine (by using Mg in THF) gives rise to CF3N=C in excellent yield but to much lower yields of CsFsNC and SF5NC.3,4 Vacuum pyrolysis at 240 C of CF2=CFNCCr(C0)5 leads smoothly to CF*=CFNC.' All of these isocyanides are very unstable compounds which tend to decompose at relatively low temperatures to form polymeric We find that the defluorination of perfluoroazaalkenes with Ph3P not only provides a more straightforward route to the previously known CF3N=C, but also allows the synthesis of the previously unknown higher homologues C*F,N=C (1) and C3F7N=C (2). The synthesis of the precursors used in our method, RfN=CF2,7,8 requires fewer steps, and the production of the isocyanides does not require the use of a s ~ l v e n t . ~ The previously described route to CF3N=C required the conversion of CF3N=CF2 into the dibromomethanimine CF3N=CBr2 via a three step synthesis which was achieved by the utilization of BBrl.Io

Synthesis and properties of a new, branched polyhydridocarbosilane as a precursor for silicon carbide

Polymerization of Cl2Si(CH3)CH2Cl with Mg in THF, followed by reduction with LiAlH4, gave a polycarbosilane with Si-H groups and branches at the Si atoms. The polymer could be cross-linked thermally at 150°C. Pyrolysis of the cross-linked material gave SiC with a yield of 70%.

Chemistry of o-xylenediyl–metal complexes. Part 5. Silicon and tin metallacycles derived from o-C6H4(C̅HR)2(R = H or SiMe3)

Treatment of SnCl2Ph2 with [Mg(LL)(thf)]6 or [Li(tmen)]2[o-C6H4{CH(SiMe3)}2]7 in OEt2 yields the stannacycle [[graphic omitted])Ph2]1 or [[graphic omitted]′-meso)Ph2]2{(LL)2–=o-C6H4(H2)2, (L′L′)2–=o-C6H4[H(SiMe3)]2, thf = tetrahydrofuran, tmen = Me2N[CH2]2NMe2}. Likewise, SnCl4 with 6 or 7 at 30 °C in OEt2 affords exclusively the stannaspirobicycle [[graphic omitted])2]3 or [[graphic omitted]′-meso)2]4; by contrast SnCl4 with 7 at –78 °C gives, together with 4(52%), the yellow, diamagnetic tin(II) metallacycle [{[graphic omitted]′-meso)}4](Sn–Sn)5(14%). Compound 5 is more conveniently prepared by treating Sn(OC6H2But2-2,6-Me-4)2 with 7; it is tetrameric in the solid and in solution, but monomeric in the gas phase and has a low first ionisation energy (7.6 eV). The compound [[graphic omitted])Me2]8 is obtained by an in situ Grignard reaction from SiCl2Me2, o-C6H4(CH2Cl)2 and Mg in thf, while [[graphic omitted]′-meso)Me2]9 is prepared from SiCl2Me2 and 7. Each of the metallacycles derived from the ligand (L′L′)2– was obtained stereospecifically as the meso diastereoisomer. X-Ray structure determinations of complexes 1–5 have been performed. The α,α′-unsubstituted metallacycles have shorter 〈Sn–Cα〉 distances (2.144 in 1, 2.147A in 3) than the corresponding α,α′-bis(trimethylsilyl) derivatives (2.166 in 2, 2.174A in 4). The C6CαCα′o-xylenediyl plane is folded relative to the MCαCα′ plane, the ‘fold angle’θ being 8.5 (1), 19.8 (2), 0.8 and 11.9 (3), 24.1 and 23.0 (4) and 20.8 °(5). The larger θ values for the [graphic omitted]L′) complexes 2 and 4 than for the their [graphic omitted]) counterparts 1 and 3(as for comparable Sn–Cα distances) is attributable to greater interligand strain and crowding around the metal centre in 2 and 4. Molecules of 5 have 4 symmetry, with Sn–Sn 2.852(3), Sn–Cα 2.15(3) and Sn–Cα′ 2.09(4)A.

Incorporation of molecular nitrogen into organic compounds III. Reaction of titanium-nitrogen complexes with acid halides and acid anhydrides

The titanium-nitrogen complex 1, [TiNMg2Cl2·THF] prepared from TiCl3 or TiCl4 and Mg in THF under nitrogen reacts with acid chloride to give amide and/or imide. The cyclic imides were obtained by the reaction of titanium-isocyanate complex 3, [3THF·Mg2Cl2OTiNCO], made from titanium-nitrogen complex 1 and carbon dioxide, and the corresponding cyclic acid anhydrides. Benzoxazone derivatives afforded the corresponding quinazoline derivatives in a similar procedure. These results indicate that molecular nitrogen was incorporated into organic compounds via titanium nitrogen complexes.

Preparation and chemistry of Me 3SiCH 2AsH 2; Preparation of [Me 3SiCH 2(H)AsGaPh 2] 3, a trimeric mono(arsino)gallane containing a hydrogen bonded to arsenic. Isolation and X-ray crystal structure of (Me 3SiCH 2As) 5

Reduction of Me 3SiCH 2AsCl 2 ( I) with LiA1H 4 at −78°C afforded Me 3SiCH 2 AsH 2 ( II) and reaction of II with Ph 3Ga produced [Me 3SiCH 2(H)AsGaPh 2] 3 ( III) which was characterized by partial elemental analysis (C and H), 1H NMR spectroscopy and a cryoscopic molecular weight determination. Based on 1H NMR data, [Me 3SiCH 2 (H)AsGaMe 2] 3 ( IV) was produced by the reaction of II with Me 3Ga; however, only H 2, Me 4Si, (Me 3SiCH 2As) 5 ( VI) and unreacted (Me 3SiCH 2) 3Ga were identified after allowing the latter to react with II. Reaction of 2 equiv. of Me 3SiCl with a mixture of II and n-BuLi (1 : 2 mole ratio) afforded Me 3SiCH 2As(SiMe 3) 2 ( V). The monosilylated arsine was not isolated when 1 equiv. of Me 3SiCl was allowed to react with combined II and n-BuLi (1 : 1 mole ratio); rather, a mixture of II and V resulted. Attempted preparations of (Me 3SiCH 2AsGaPh) n , are described. The ring compound, VI, was prepared by reaction of I with a mixture of Me 3SiCl and Mg in THF. The molecular structure of this cycloarsane was determined by single-crystal X-ray diffraction methods. Pale yellow crystals of VI belong to the monoclinic system with four molecules occupying the general positions of space group P2 1/ c( C 2 h 5)with cell constants: a = 9.952(1), b = 30.245(9), c = 13.000(3) Å, β = 91.69(1)°, V = 3911.3 Å 3, Z = 4.

ChemInform Abstract: Synthesis of Pentafluorophenyl Isocyanide and Its Stabilization as a Ligand, Cp*Mn(CO)2(CN‐C6F5).

AbstractThe title isocyanide (IV) is obtained for the first time in analytically pure form by dehalogenation of (III) with Mg in THF.

Carbanions as Intermediates in the Synthesis of Grignard Reagents

Evidence for the occurrence of R⊖ in reaction (a) is provided by the isolation of compounds such as 2 in the reaction of 1 with Mg in THF after addition of Me3GeCl. On the basis of a series of comparative experiments it could be concluded that a carbanion intermediate is probably responsible for the stannyl migration.

ChemInform Abstract: Metal Colloids Produced by Means of Gas Evaporation Technique. Part 4. Size Distribution of Small Mg and In Particles.

AbstractSmall metal particles (Mg in THF and In in acetone) have been prepared by the matrix isolation method, the gas flow‐solution trap method, and the gas flow‐cold trap method and the size distribution of the particles has been determined by electron microscopy.

Interaction of titanocene generated in the system Cp 2TiCl 2 + Mg in thf with benzyne and tolane. A novel route to titanaindene and titanacyclopentadiene complexes

Direct synthesis of the titanaindene complex Cp 2Ti[ o-C 6H 4C(Ph)C(PH)] through of reaction of tolane with Cp 2Ti and benzyne, generated in the system Cp 2TiCl 2 + Mg + o-fluorobromobenzene in THF is described. Under similar conditions, reaction of Cp 2TiCl 2 with Mg in THF, in the presence of tolane only (ratio Cp 2TiCl 2/Mg/Ph 2C 2 ≈ 1/1/2) yields the titanacyclopentadiene complex Cp 2Tic(Ph)C(Ph)C(PH)C(Ph).

Efficient preparation of allylic grignard reagents using slurries of precondensed magnesium

Using a simple apparatus addition of 2-alkenyl halides to precondensed active Mg in THF gave clean solutions of 2-alkenylmagnesium halides which on carbonation furnished β,γ-unsaturated carboxylic acids in high yields.