Gold-chromium compounds

Chromate conversion coatings are thin, noncrystalline, adherent surface layers of low solubiHty phosphoms and/or chromium compounds produced by the reaction of suitable reagents with the metal surface (2,3). The two classes of chromate coatings are chromium phosphates (green chromates) and chromium chromates (gold chromates). 

In a sense, each element seems to have its own personality. The noble gases— helium, neon, argon, and the rest—seem aloof, independent, uninterested. Precious metals, including silver, gold, and platinum, impress me as serene, quiet, confident. Chromium, a shiny metal that forms many highly colored compounds appears to be a rock star among the elements, as does neodymium, the key element in early lasers. 

Nonpolar molecular compounds dissolve in nonpolar solvents. Polar molecular compounds and ionic compounds may dissolve in polar solvents. Metals dissolve in other molten metals. These can range from copper, silver, gold, alkali metals dissolving in mercury at room temperature, to chromium, molybdenum, and tungsten dissolving in molten iron. 

Bis(adamantylimido) compounds, with monomeric chromium(VI) complexes, 5, 348 Bis(alkene) complexes conjugated, Rh complexes, 7, 214 mononuclear Ru and Os compounds, 6, 401 -02 in Ru and Os half-sandwich rj6-arenes, 6, 538 with tungsten carbonyls and isocyanides, 5, 685 Bis(u-alkenylcyclopentadienyl) complexes, with Ti(II), 4, 254 Bis(alkoxide) nitrogen-donor complexes, with Zr(IV), 4, 805 Bis(alkoxide) titanium alkynes, in cross-coupling, 4, 276 Bis(alkoxo) complexes, with bis-Cp Ti(IV), 4, 588 Bis[alkoxy(alkylamino)carbene]gold complexes, preparation, 2, 288... 

Ferrocenyl ligands, via zinc reagents, 9, 120 Ferrocenylmethyl phosphonium salts, with gold(I), 2, 274 Ferrocenylmonophosphine, in styrene asymmetric hydrosilylation, 10, 817 Ferrocenyl oxazolines, synthesis, 6, 202 Ferrocenylphosphines with chromium carbonyls, 5, 219 in 1,3-diene asymmetric hydrosilylation, 10, 824-826 preparation, 6, 197 various complexes, 6, 201 Ferrocenylselenolates, preparation, 6, 188 Ferrocenyl-substituted anthracenes, preparation, 6, 189 Ferrocenyl terpyridyl compounds, phenyl-spaced, preparation 6, 188 Ferrocifens... 

Polyhydroxy compounds are oxidized by such metal ions as vanadium(V), chromium(VI), cerium(IV), iridium(IV), and gold(III), among others. These oxidations were found to be catalyzed by acids.171 173 Vanadium(V) and chromium(VI) are closely related in their chemical properties, but the reduction of V(V) is difficult compared with that of Cr(VI) because of its lower redox potential [V(V)-V(IV) = 1.00 V Cr(VI)-Cr(III) = 1.20 V], However, the redox potential increases at lower pH values, facilitating the oxidation of sugars. 

Early attempts to prepare stable, isolable, cr-bonded organic derivatives of the transition metals were almost uniformly unsuccessful, except for certain organometallic derivatives of platinum and gold. It has already been mentioned that the V-bonded organochromium compounds of Hein and co-workers were in fact 7r-bonded arene-chromium derivatives. A detailed and critical account of these earlier studies was written in 1955 by Cotton (53). 

Nitric acid is a strong oxidizing agent that reacts with alkali and basic materials as well as oxides. Concentrated nitric acid reacts violently with many organic compounds. Nitric acid attacks most metals except for platinum, gold, aluminum, and chromium steel. 

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