Metal selenides synthesis

Use of 1,2,3-selenadiazoles as precursors of intermediary selenirenes has been discussed extensively in the preceding sections. Furthermore, their use in alkyne and metal selenide synthesis is treated in Section 1.07.12. Consequently, there is no need for further discussion here. 

A similar reduction of selenium with a metal naphthalenide provides an in situ synthesis of alkali metal selenides and diselenides.3... 

The synthesis of hexamethyldisilathiane from sodium sulfide and chloro-trimethylsilane is described here. The present method is based on the convenient in situ syntheses of alkali metal selenides and diselenides. Commercial sodium sulfide or lithium sulfide are reported to be poor substitutes for in situ generated sulfides in this reaction. For example, in 1961 Abel reported that disodium sulfide reacts with chlorotrimethylsilane in pressure vessels at 250°C for 20 h to produce I. Our procedure is very convenient, utilizing readily available starting materials and apparatus under mild conditions. The yields are t3q)ically 80-88% at 0.3-mol scale. However, it can be improved to 90-95% on small scale ( 50-mmol) reactions. This procedure can be applied to the synthesis of various disilathianes. 

The completion of the synthesis of key intermediate 2 requires only a straightforward sequence of functional group manipulations. In the presence of acetone, cupric sulfate, and camphorsulfonic acid (CSA), the lactol and secondary hydroxyl groups in 10 are simultaneously protected as an acetonide (see intermediate 9). The overall yield of 9 is 55 % from 13. Cleavage of the benzyl ether in 9 with lithium metal in liquid ammonia furnishes a diol (98% yield) which is subsequently converted to selenide 20 according to Grie-co s procedure22 (see Scheme 6a). Oxidation of the selenium atom... 

RAFT polymerization lends itself to the synthesis of polymers with thiol end groups. Several groups have utilized the property of thiols and dilhioesLers to bind heavy metals such as gold or cadmium in preparing brushes based on gold film or nanoparticles1 8 761 763 and cadmium selenide nanoparticles.763 76 1... 

The most intensive development of the nanoparticle area concerns the synthesis of metal particles for applications in physics or in micro/nano-electronics generally. Besides the use of physical techniques such as atom evaporation, synthetic techniques based on salt reduction or compound precipitation (oxides, sulfides, selenides, etc.) have been developed, and associated, in general, to a kinetic control of the reaction using high temperatures, slow addition of reactants, or use of micelles as nanoreactors [15-20]. Organometallic compounds have also previously been used as material precursors in high temperature decomposition processes, for example in chemical vapor deposition [21]. Metal carbonyls have been widely used as precursors of metals either in the gas phase (OMCVD for the deposition of films or nanoparticles) or in solution for the synthesis after thermal treatment [22], UV irradiation or sonolysis [23,24] of fine powders or metal nanoparticles. 

Ordered mesoporous materials of compositions other than silica or silica-alumina are also accessible. Employing the micelle templating route, several oxidic mesostructures have been made. Unfortunately, the pores of many such materials collapse upon template removal by calcination. The oxides in the pore walls are often not very well condensed or suffer from reciystallization of the oxides. In some cases, even changes of the oxidation state of the metals may play a role. Stabilization of the pore walls in post-synthesis results in a material that is rather stable toward calcination. By post-synthetic treatment with phosphoric acid, stable alumina, titania, and zirconia mesophases were obtained (see [27] and references therein). The phosphoric acid results in further condensation of the pore walls and the materials can be calcined with preservation of the pore system. Not only mesoporous oxidic materials but also phosphates, sulfides, and selenides can be obtained by surfactant templating. These materials have pore systems similar to OMS materials. 

Synthesis of sulfo-selenide Chevrel phases Phases ofM Mo x xSex composition (M = Cr, Mn) were prepared by the reaction of stoichiometric mixtures of MoS2 and MoSe2 binary powders with Mo and Cr, or Mn, metallic powders (Mantjour-Billah and Chevrel 2004). The mixtures were pressed into pellets and then (inside an alumina crucible) sealed in evacuated silica tubes. After heating to 800°C and then to 1000°C for 24 hours, two further grinding and annealing (at 1000°C) treatments were performed. Powder X-ray diffraction methods were used to study the solid solutions, the trend of the lattice parameters, etc. 

Although the topic of sonoelectrochemistry will be treated in the subsequent section, it should also be mentioned that pulsed sonoelectroreduction of metallic salts gives rise to finely divided reactive metals which can be employed in organometallic synthesis see above [85]. The synthesis of nanocompounds of semiconductors such as cadmium and lead selenides can also be achieved using similar methodology [169]. 

This chapter deals with the methods of synthesis, characterization, and growth mechanisms of well-defined uniform particles of metal sufides and selenides formed by direct reaction of metal ions with the chalcogenide ions, released from thioacetamide or selenourea in dilute solutions, or supplied continuously from outside in the form of a high concentration of sulfide ions. 

Hydrogen ligands, 689-711 Hydrogen selenide metal complexes, 663 Hydrogen sulfide metal complexes, 516 Hydrogen telluride metal complexes, 670 Hydroporphyrins, 814-856 basicity, 853 dehydrogenation, 853 demetallation, 854 deuteration, 853 mass spectra, 852 metallation, 854 NMR, 852 non-aromatic, 855 photochemistry, 854 redox chemistry, 855 synthesis, 852... 

---