Organometallic route

iV-dimethyl-4-bromoaniline (1.00 g, 5 mmol) was dissolved in THF (20 ml) and cooled to -78°C. Butyllithium (3.12 ml of 1.6 M, 1.60 mmol) in hexane was added. After stirring for 30 min at —78°C, bismuth chloride (0.5 g, 1.59 mmol) dissolved in THF (10 ml) was added and the resulting mixture was stirred for 1 h at -78°C, then allowed to warm up to 23°C. After stirring for an additional 12 h at this temperature, the solvent was removed in vacuo and the residue was extracted with toluene (20 ml). The toluene extract was filtered and concentrated to about 10 ml. When the solution was allowed to stand at 0°C for a few days, the product was obtained as colorless crystals (0.96 g, 86%), m.p. 200°C (decomp.) [960M5613]. 

To a yellowish solution of chlorobis(2,4,6-triisopropylphenyl)bismuthine (329 mg, 0.5 mmol) in THF (10 ml) was added methyllithium (1.0 M ether solution 0.5 ml, 0.5 mmol) at -78°C. After stirring for 10 min at -78°C, the reaction mixture was allowed to warm to room temperature gradually and the solvent was evaporated under reduced pressure. Chromatography of the solid residue on silica gel using hexane-ethyl acetate gave the expected unsymmetrical bismuthine as a colorless crystalline solid (262 mg. 77%), m.p. 53-55°C [92BCJ3504]. 

Tris-or(/j -lithiation of tris[2-(diethylsulfamoyl)phenyl]bismuthine with ferf-butyllithium followed by treatment with 3 equiv. of diaryliodobismuthine yields a branched tetrameric bismuthine, which, on similar treatment, leads to a dendrimer-type bismuthine [97CC2295], 

Bismuth bromide (1.84 g, 4.11 mmol) and Cd(C(jF5)2-diglyme solvate (3.83 g, 6.60 mmol) were dissolved in acetonitrile (10 ml) and the solution was heated at 50°C for 12 h. The solvent together with traces of diglyme and pentafluorobenzene were distilled off, and the gray solid residue was sublimed twice at 60°C/2 X lO mmHg to give the product (2.07 g, 71%) [87JOM(334)323]. 

Lithium tetraethylaluminate (10.0 g, 67 mmol) in ether (50 ml) was treated with freshly sublimed bismuth chloride (15.0 g, 46 mmol) in the same solvent (50 ml). A large quantity of gray precipitate was formed. After refluxing for 1 h and subsequent hydrolysis, triethylbismuthine was extracted with ether. The bulk of the solvent was removed by fractional distillation through an efficient column and the residue was further fractionated under reduced pressure to give pure bismuthine (12.0 g, 85%), b.p. 90°C/48 mmHg [62AJC710]. 

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A potentially useful route to substituted (Z)-allylboron derivatives involves the selective cis hydrogenation of propynylboron derivatives. One recent report applied this approach in the synthesis of a (Z)-3-trimethylsilyl-2-propenylboronate, which cannot be prepared by the allyl-organometallic route discussed in Section 1.3.3.3.3.1.1.1. The selectivity for the Z-isomer was only 9 1 21. The scope of this method remains to be fully documented35. 

The catalysts prepared by the organometallic route can be divided into three groups ... 

Recently a number of linear and branched oligosilane derivatives have been synthesized from easily accessible precursors using mainly organometallic routes [1,2]. Now we are able to report on the first successful synthesis of tetrasilanes of the general formula H3SiSiHXSiHXSiH3 (X = Ph, Cl, Br) bearing internal substituents. 

Figure 2.16 Characterization by high-resolution electron microscopy of a bimetallic nanoparticle of a Pt-Sn alloy obtained via the surface organometallic route.

Figure 3.37 Activity and selectivity in the reaction of isobutane dehydrogenation to isobutene with nanoparticles of Pt/silica (a) and with Pt/Sn bimetallic nanoparticles/silica obtained via the organometallic route (b).

Several synthetic methods for the preparation of semiconductor nanoparticles have been reported. Colloidal and organometallic routes have probably been identified as the two major methods in use [11-16], although nano dimensional particles have been also synthesized in confined matrices such as zeolites [17], layered solids [18], molecular sieves [19,20], vesicles/micelles [21,22], gels [23,24], and polymers [25]. An ideal synthetic route should produce nanoparticles which are pure, crystalline, reasonably monodisperse and have a surface which is independently derivatized. 

Anilkumar, R. Burton, D. J. A highly effrcient room temperature non-organometallic route for the synthesis of r/./f/j-tri fluoro styrenes by dehydrohalogenation. Tetrahedron Lett. 2003, 44, 6661-6664. 

The Eschenmoser reaction is extremely useful for the conversion of amides into enaminoesters via the thioamide reaction with a-haloesters, and triphenylphosphine mediated sulfide contraction, and we are fortunate that Shiosaki has published a thorough review on this topic [180]. The accompanying scheme shows a typical example for which an organometallic route with a lithium or a zinc enolate was not successful [181]. 

Figure 30. STM image of a platinum raft on a graphite powder particle. An organometallic route was used to deposit the metal at low temperatures. The discrimination of metal and graphite with the same lattice geometry is possible by the different lattice parameters...

High Refraction Index Polysiloxanes via Organometallic Routes - An Overview... 

Ganicz T, Kowalewska A, Stahczyk WA et al. (2005) A novel organometallic route to phenylethenyl-modified polysiloxanes. J. Mater. Chem. 15 611-619... 

Organometallic routes are frequently applied to the synthesis of vinylboranes. Vinyltin and vinylzirconium reagents, for instance, serve as precursors for the preparation of vinylboranes, in which the boron centers are not electronically stabilized by oxygen or nitrogen substituents. Moreover,... 

The organometallic route can be extended to the formation of one-dimensional indium materials. On the use of long-chain amines as templates. In and InsSn nano wires have been prepared from the organometallic precursors InCp (Cp = 5115 ) in the presence of UV irradiation. In this case, irradiation is cmcial for the formation of the wires. In nanowires are also produced in the metal organic chemical vapor deposition grown InGaN layers. ... 

Anhydrous lanthanide trihalides, particularly the trichlorides, are important reactants for the formation of a variety of lanthanide complexes, including organometallics. Routes for the syntheses of anhydrous lanthanide trihalides generally involve high temperature procedures or dehydration of the hydrated halides.The former are inconvenient and complex for small scale laboratory syntheses, while dehydration methods may also be complex and have limitations, for example, use of thionyl chloride. - Moreover, the products from these routes may require purification by vacuum sublimation at elevated temperatures. Redox transmetalation between lanthanide metals and mercury(II) halides was initially carried out at high temperatures. However, this reaction can be carried out in tetrahydrofuran (THF, solvent) to give complexes of lanthanide trihalides with the solvent. These products are equally as suitable as reactants for synthetic purposes as the uncomplexed... 

Flow methods have the advantage of the potential for continuous processing but are rare. It has been pointed out that cheap solvents can be used in solvothermal methods [65]. It is clear from the literature that the majority of semiconductor dots and the few being sold are today being made by batch methods based on metal organic or organometallic routes. 

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