Benzene-, lithium complex with

Opening of a bottle where some particles of lithium aluminum hydride were squeezed between the neck and the stopper caused a fire [68]. Lithium aluminum hydride must not be crushed in a porcelain mortar with a pestle. Fire and even explosion may result from contact of lithium aluminum hydride with small amounts of water or moisture. Sodium bis(2-methoxy-ethoxy)aluminum hydride (Vitride, Red-Al ) delivered in benzene or toluene solutions also may ignite in contact with water. Borane (diborane) ignites in contact with air and is therefore kept in solutions in tetrahydrofuran or in complexes with amines and sulfides. Powdered lithium borohydride may ignite in moist air. Sodium borohydride and sodium cyanoborohydride, on the other hand, are considered safe. ... 

Iron-acyl enolates, such as 2, prepared by x-deprotonation of the corresponding acyl complexes with lithium amides or alkyllithiums, are nearly always generated as fs-enolates which suffer stereoselective alkylation while existing as the crmt-conformer which places the carbon monoxide oxygen anti to the enolate oxygen (see Section 1.1.1.3.4.1.). These enolates react readily with strong electrophiles, such as primary iodoalkanes, primary alkyl sulfonates, 3-bromopropenes, (bromomethyl)benzenes and 3-bromopropynes, a-halo ethers and a-halo carbonyl compounds (Houben-Weyl, Volume 13/9 a, p 413) (see Table 6 for examples). 

The synthesis of the zero-valent, 1,3-cyclohexadiene benzene ruthenium complex 196a has been mentioned as a coproduct of the cyclohexadienyl complex 236a in the reduction of the benzene ruthenium dication 235 with lithium aluminum hydride. Reduction of 235 with sodium borohydride in THF, however, gives only the air-sensitive, yellow-green ruthenium(O) complex 196a (118). This reaction has been generalized to... 

Enolate Alkylations with Transition Metal Coordinated Electrophiles. Coordination of various transition metals to dienes and aromatic compounds sufficiently activates these compounds to nucleophilic addition, resulting in high asymmetric induction at the a-center. However, the manganese complexes of various benzene derivatives couple with lithium enolates in low selectivity at the nascent stereogenic center on the ring (eq 15). ... 

The lithiated derivative (LiCgH5)Cr(CO)3 has been prepared in high yield by the reaction of [(CO)3Cr](CaHgHgC6H5)[Cr(CO)3] with re-butyl lithium. Complexes, such as 2-phenylpyridine chromium tricarbonyl and (Ph2PCgHg)Cr(CO)3, which are not otherwise obtainable were prepared by the reaction of the lithiated derivative with pyridine and PhaPCl, respectively 348). Benzene chromium tricarbonyl has been metalated by treatment with re-butyl lithium in THF and after carbona-tion yielded w-benzoic acid chromium tricarbonyl 304). 

Rathice and Kow first reported the preparation of a boron-stabilized carbanion by direct deprotonation of the carbon acid. They made the important observation that the deprotonation needed a sterically demanding base to prevent its complexation with boron. Thus the anion of B-methyl-9-borabicy-clo[3.3.1]nonane, prepared by deprotonation with lithium 2,2,6,6-tetramethylpiperidine (LiTMP) in benzene, can be alkylated successfully. 

Solid complexes of defined stoichiometry have been prepared for all the lithium halides with HMPA. For LiBr, both [LiBr(HMPA)2] and [LiBr(HMPA)4] have been obtained as solids of defined m.p., but the 1 1 complex, the kinetically active species for epoxide rearrangement, has not been isolated. The rate of epoxide loss and solubility of LiBr increased proportionately with added solubilizer (HMPA), to a maximum rate at a 1 1 ratio of addend LiBr. Additional HMPA beyond this ratio caused the rate to decrease even though all the LiBr remained in solution. At an addend LiBr ratio of 2 1, the reaction effectively ceased. These observations allow the conclusions that [LiBr(HMPA)2] is more stable than the reactive 1 1 complex in benzene, and that only the latter is kinetically competent. 

DUsobutylaluminum hydride, (CH3)2CHCH2AlCH,CH(CHa)j. Mol. wt. 142.21, b.p, 140°/4 mm. Supplier (i lb. unit in pressure cylinder) Texas Alkyls Inc. (Techn, Bull. Pi 640,928, 1964). Being a liquid, the reagent is dissolved more easily than lithium aluminum hydride. Suitable solvents are ether, benzene, toluene, and cyclohexane. Tetrahydrofurane forms a complex with the hydride and is not suitable. Since the reagent is pyrophoric in concentrated form, all operations with this and other organoaluminum compounds must be conducted in an oxygen-free atmosphere. ... 

Screttas and Eastham found that this base forms crystalline complexes with organometallic compounds of magnesium, lithium, and zinc. Thus on addition of a benzene solution of TED to a solution of butyllithium a crystalline complex separates the composition is BujLij —TED-Bu Lia. Triethylamine (1) and quinu-clidine (2) form similar complexes but they are considerably more soluble than the corresponding TED complex. 

The data in Table V were obtained by sequential treatment of the initial sample with sodium iodide and lithium chloride. Complexation with sodium iodide was done in a heptane-benzene slurry. The sparingly soluble sodium iodide chelate was isolated by filtering the mixture. The remaining solution was concentrated, and the residue obtained was contacted with lithium chloride in pentane. After stirring this heterogeneous mixture, a solid lithium chloride chelate complex was isolated by filtration. Decomposition of the alkali-metal salt complexes followed by recovery and analysis of the polyamine components showed that the sodium iodide complex contained 82.6% n-HMTP while the LiCl complex contained 94.8% N,N -c-PMPP. Table V shows that the initial polyamine sample contained 48.8 and 11.4% of these ligands, respectively. 

Fig. 2 Space filling representation of a receptor comprised of (benzene)Ru complexes and the ligand L3 with a sodium ion (left) or a lithium ion (right) in the binding pocket. Larger cations do not bind to the receptor because they are efficiently blocked by the arene 7r-ligands...

Carboranyl derivatives of lanthanum, thulium and ytterbium are formed when the C-mercuro derivatives of methyl- and phenylcarboranes react with the rare earth metals in tetrahydrofuran at 20°C (Suleimanov et al., 1982a), or from the lithium derivatives of methyl- and phenylcarboranes with the rare earth trichlorides in benzene-ether at 20°C (Bregadze et al., 1983) as complexes with THF. A carboranyl derivative with a thulium-boron bond is also described. The reaction (eq. 62) may proceed via the formation of B-Tm-C derivatives, followed by disproportionation. 

The polymerization of acrylate esters by organomagnesium reagents is best described as pseudo-anionic monomer is complexed to a magnesium atom covalently bonded to carbon. The anionic polymerization of methyl methacrylate in benzene yields the syndiotactic polymer when the initiator is an alkali metal complexed with 18-dicyclohexyl-6-crown. When a solution of methyl methacrylate in toluene is placed below a solution of butyl-lithium in the same solvent at —78 °C so as to avoid any mechanical mixing, the polymer obtained has a higher isotacticity than that observed if the solutions are stirred. ... 

The polarity of the Li—C bond is so much increased by co-ordination with TMED that the TMED n-butyl-lithium complex adds ethylene under moderate pressure giving polymers. Reaction in the presence of benzene gives phenyl-ended telomers ... 

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