Mercury II selenide

Mercury(II) coordination compounds containing Se or Te donor atoms constitute a rather neglected area of coordination chemistry. Often the species show similarities to the corresponding sulfur compounds (see Table 17). Mercury(II) selenide, HgSe, and mercury(II) telluride, HgTe, are simply formed by direct combination of the elements.4 Single crystals are available by chemical transport methods using a pure H2 or Ar stream.402 X-Ray diffraction... 

The other chalcogenides see Chalcogens) mercury(II) selenide, HgSe and telluride, HgTe, can be synthesized directly from the elements. Both compounds have a zinc blende structure and function as semiconductors. The selenide is violet black, and the telluride is black. 

In four studies, the solubility product of mercury(II) selenide in the aqueous phase has been estimated from polarographic measurements of the reduction potential of the couple HgSe(s) + 2e Hg(l) + Se . This datum combines with the standard electrode potential of Hg VHg(l) to the solubility product. The results are collected in Table V-58. 

Ammonium sulphide) Barium sulphide Calcium sulphide Chromium (II) sulphide Copper (II) sulphide Diantimony trisulphide Dibismuth trisulphide Dicaesium selenide Dicerium trisulphide Digold trisulphide Europium (II) sulphide Germanium (II) sulphide Iron disulphide Iron (II) sulphide Manganese (II) sulphide Mercury (II) sulphide Molybdenum (IV) sulphide... 

Hexaazido-2,4,6-triaza-1,3,5-triphosphorine, 4795 Hydrogen azide, 4441 f Hydrogen selenide, 4486 f Hydrogen telluride, 4488 Iodoform, 0376 Lead(II) azide, 4782 Lead(IV) azide, 4790 Mercury(II) cyanide, 0976 Mercury(II) fulminate, 0978... 

Vinyl selenides have been lithiated at the a-position by LDA983,984 at —78 °C in THF to give a-(arylselanyl)vinyllithiums 680, a-(methylselanyl)vinyllithiums 681 being obtained by selenium-lithium transmetallation from l,l-bis(methylselanyl)alkenes with n-BuLi in THF or t-BuLi in ether at —78 °C985 986. These intermediates reacted with alkyl halides, epoxides, carbonyl compounds and DMF985, the final deprotection being performed by mercury(II) salts986. 

Nitroselenenylation of alkenes141-149 is performed in a mixture of acetonitrile/tetrahydro-furan (compared to the nitromercuration reaction, this allows application to alkenes that may be insoluble in water) by the addition of phenylselenenyl halides, mercury(ii) chloride, and silver nitrite. Mercury chloride is necessary to significantly or completely suppress the formation of -hydroxy selenides due to the ambident character of the nitrite anion. 

Ionic reactions between solvo-acids and solvo-bases may lead to insoluble products such as thallium sulphate formed from mercury(II) sulphate and thallium bromide in molten mercury(II) bromide. Similarly anhydrous copper(II) sulphate can be prepared by using a copper(II) halide. Perchlorates, nitrates and phosphates of many other elements can be prepared in a similar manner. By allowing mer-cury(II) oxide to react with the sulphate in mercury(II) bromide solution a red, insoluble product of composition (Hg0)2HgS04 is formed. Analogous compounds are formed from the sulphide, selenide and telluride of mercury in molten mercuric bromide. 

C1BH12M0S6, Tris(benzene-1,2-dithiolato)molybdenum(VI), 42B, 942 ClbHi2N2PdS2, Bis(8"mercaptoquinolinato)palladium, 39B, 824 ClbHi2N2PtS2 f Bis(8-mercaptoquinolinato)platinum, 39B, 824 ClbHj 3O9OS3PS2 f (M"Hydrido)-(M"dithioformato)-bis(tricarbonyl-osmium)-tricarbonyl(dimethylphenylphosphine)osmium, 46B, 1212 ClbHi5Cl2HgPSe, Triphenylphosphine selenide mercury(II) chloride, 40B, 1128... 

Commonly used II-VI compounds include zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium telluride, and mercury cadmium telluride. These materials are not as widely used as the III-V compounds, one reason being that it is difficult to achieve p-type doping. Mercury cadmium telluride is used extensively in military night sights, which detect in the 8-13 im spectral band (a similar material, platinum silicide, is being developed for that purpose). The major applications ofCVD II-VI compounds are found in photovoltaic and electroluminescent displays. 

The next five chapters deal with deposition of specific groups of semiconductors. In Chapter 4, II-VI Semiconductors, all the sulphides, selenides, and (what little there is on) tellurides of cadmium (most of the chapter), zinc (a substantial part), and mercury (a small part). (Oxides are left to a later chapter.) This chapter is, understandably, a large one, due mainly to the large amount of work carried out on CdS and to a lesser extent on CdSe. Chapter 5, PbS and PbSe, provides a separate forum for PbS and PbSe, which provided much of the focus for CD in earlier years. The remaining sulphides and selenides are covered in Chapter 6, Other Sulphides and Selenides. There are many of these compounds, thus, this is a correspondingly large chapter. Chapter 7, Oxides and Other Semiconductors, is devoted mainly to oxides and some hydroxides, as well as to miscellaneous semiconductors that have only been scantily studied (elemental selenium and silver halides). These previous chapters have been limited to binary semiconductors, made up of two elements (with the exception of elemental Se). Chapter 8, Ternary Semiconductors, extends this list to semiconductors composed of three elements, whether two different metals (most of the studies) or two different chalcogens. 

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