Mercury sulfide structure

Vermilion and cinnabar are two bright red, toxic minerals that share an identical composition (they are both composed of mercury sulfide) but have different crystal structures. Two kinds of vermilion are known one of natural origin and another made artificially. Finely ground natural vermilion may vary in hue from red to liver-brown and even to black. Artificial vermilion was made from mercury and sulfur the method of preparation seems to have been developed by the Chinese and was introduced into Europe only during the eighth century c.e. (Gettens et al. 1972). 

Bistrifluoromethyl sulfide XLVII undergoes photolysis with ultraviolet light in a silica vessel, but not in Pyrex glass, yielding bistrifluoromethyl sulfide (XLIX) and sulfur.27 Possibly, irradiation leads to isomerization of XLVII and XLVIII, followed by S-S bond fission to give two CFjS- free radicals a view supported by the formation of bis(trifluoromethylthio)mercury (L) in the presence of mercury. The structures assigned for XLVII and XLIX find support from spectroscopic data.28... 

The most important mercury chalcogenide halides are of the type HgaYjXj (Y = S, Se, Te X = Cl, Br, I). The corresponding sulfide halides have been known for over 150 years (326). Quite a lot of work has been performed concerning the preparation, structures, electronic and optical properties, and phototropic behavior of these compounds. Mercury chalcogenide halides of other compositions have been mentioned in the literature (141). As most of these compounds are not well established, they will not be treated in detail, with the exception of the latest contributions (see Table V). 

Interesting molecular mercury zinc sulfides Hg[SZn(3-Ph-5-Mepz)3BH]2 and PhHg[SZn(3-Ph-5-Mepz)3BH] (pz = pyrazole) have been obtained and structurally studied.336... 

Irradiation of aliphatic thiols, sulfides, and disulfides with a mercury lamp produces gaseous products identified by the mass spectrograph. Thiols are the least stable to light, with the formation of hydrogen95-129 as the main product. Sulfides and disulfides yield, as the predominant products, saturated hydrocarbons of structures corresponding to the smallest alkyl radical attached to sulfur. Haines et al.95-97 have offered a mechanism to explain the predominant production of hydrogen during photolysis of thiols. 

Mercury(II) sulfide, HgS, is dimorphic. Metacinnabarite, a rare mineral, is obtained by precipitation from aqueous acidified mercury(II) chloride by H2S.351 It crystallizes in the zinc blende structure in which HgK forms tetrahedral bonds (Hg—S = 253pm) it is stable above 400 °C.352 The more common form, cinnabar, is obtained from the elements or by passing H2S into mercury(II) acetate in hot glacial acetic acid containing NH4SCN.351 It crystallizes in the space group P 3221 and consists of infinite —Hg—S—Hg—S— chains spirally wound on axes... 

Lovenberg, Buchanan, and Rabinowitz found that treatment of ferredoxin with iodoacetate or N-ethylmaleimide in either the presence or absence of 8 M urea had no effect on its spectral characteristics. Less than 1 mole of carboxymethyl cysteine was formed per mole of protein when native ferredoxin was treated with iodoacetate-1-C14 (Table 10). Sobel and Lovenberg (96) showed recently that C14-iodoacetate did not react appreciably with reduced ferredoxin. However, Table 10 shows that if ferredoxin was treated with 2-mercaptoethanol in 8 M urea, it was alkylated with iodoacetate. This demonstrated that the half-cystine residues of native ferredoxin were not present as free sulfhydryls, and the mercurial titration data given above showed that they were not present as disulfides. The two observations were consistent, therefore, with a structure in which the half-cystine residues are present as cysteine and are bonded with the iron by a sulfide bridge. 

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