Reactions with metal selenides

Sources. Produced by reaction of acids or water with metal selenides... 

Phosphorus Triselenide or Phosphorous Selenide, P2Se3.— This compound may be obtained by heating together phosphorus and selenium in the requisite atomic proportions. The reaction is accompanied by a great evolution of heat. The product is a ruby-red solid, which is combustible on heating. It is insoluble in carbon disulphide. With metal selenides it forms double selenides of the typeP2Se3.2MSe.2... 

Zinc selenide (lrtran-4) 20,000-650 2.4 Brittle releases H2Se, a toxic material, if used with acids water insoluble electrochemical reactions with metal salts or complexes are possible... 

The reaction of Pl SnLi with selenium in THF at room temperature led to the lithium triphenyltin selenide, which had been trapped by reaction with metal-14 halides (Scheme 18)2. 

Reactions with metals produce selenides and tellurides as illustrated by the reactions... 

Despite the synthetic potential of the phosphine selenides, their reactions with metal carbonyls have been explored only to a limited extent until the last three years, and most of the previously described chalcogenido-carbonyl clusters containing Group 15 donor ligands had been obtained by substitution reactions. ... 

As discussed earlier the whole process is a redox reaction. Selenium is reduced using sodium borohydride to give selenide ions. In the above reaction, the metal ion reacts with the polymer (PVP or PVA) solution to form the polymer-metal ion solution. Addition of the selenide ion solution to the polymer-metal ion solutions resulted in instantaneous change in the colour of the solutions from colourless to orange (PVA) and orange red (PVP). This indicates the formation of CdSe nanoparticles. The addition of the selenide solution to the polymer - metal ion solution resulted in gradual release of selenide ion (Se -) upon hydrolytic decomposition in alkaline media (equation 4). The released selenide ions then react with metal ion to form seed particles (nucleation). 

The induced co-deposition concept has been successfully exemplified in the formation of metal selenides and tellurides (sulfur has a different behavior) by a chalcogen ion diffusion-limited process, carried out typically in acidic aqueous solutions of oxochalcogenide species containing quadrivalent selenium or tellurium and metal salts with the metal normally in its highest valence state. This is rather the earliest and most studied method for electrodeposition of compound semiconductors [1]. For MX deposition, a simple (4H-2)e reduction process may be considered to describe the overall reaction at the cathode, as for example in... 

Diselenophosphate complexes are prepared from the interaction of metal salts and complexes with appropriate diselenophosphoric acid or its salt. The acids are obtained from the reaction of phosphorus(V) selenide with alcohols 229). The preparation of phosphorus(V) selenide and its reactions with alcohols 229) and amines 22°) have been described and a variety of complexes reported (Table 4). The biological activity of these compounds does not seem to have described but the exercise of extreme caution when handling these materials is recommended. Zingaro and his coworkers 229-232) thoroughly characterized the thermal and spectroscopic properties of a number of compounds. 

In contrast, the analogous diethyl-diselenocarbamates (dsc) have been shown to be poor sources for the deposition of ZnSe or CdSe films. Under similar reaction conditions (10 -10 Torr, 370-420° C) the diethyl dsc precursors give films of the metal selenide heavily contaminated with selenium [108]. However the mixed alkyl dsc complex Eq. 4 have been used successfully to deposit thin films of CdSe or ZnSe [109,110]. 

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. 

Considering that homogeneous precipitation of metal chalcogenides (mainly sulphides) by reaction between metal ions and dissolved chalcogen is well established, the main difference between this deposition and similar reactions seems to be that the products adhere to a substrate to give a visible fdm (in this case) rather than only precipitate. Whether this is connected with the redissolu-tion/redeposition process that occurs with the Sn-S system or has some other explanation is important. If the former, it may be limited to only those systems that behave similarly. Otherwise it is not unreasonable to expect that other metal sulphides and selenides (possibly also tellurides, although tellurium tends to be much less soluble, if at all, in such solvents) may be deposited as films in this manner. 

Cadmium chromium(III) selenide can be prepared by the direct combination of the elements or by the reaction of cadmium selenide with chromium(III) selenide. Crystals of cadmium chro-mium(III) selenide have been prepared by flux growth1 in cadmium chloride, by vapor transport,2 and by a liquid-transport method3 with a platinum metal catalyst. The synthesis given... 

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