Talk:Chromium(III) chromate

Unusual compound
Chromium(III) chromate should be relevant, or at least interesting, because the cation and oxoacid anion are both based on the same element (Chromium).

Other similar combinations might be real, fantasies, or misnomers. Manganese manganate MnMnO3 CAS 39432-47-8 might or might not be the same as manganese(III) oxide Mn2O3 CAS 1317-34-6. -A876 (talk) 22:52, 13 May 2014 (UTC)


 * This is usually considered a mixed valent oxide; chromium has a number of these. The crystal structure of Cr5O12 is known ( Wilhelmi, Acta Chemica Scandinavica, 1965, 165-176). Formulating as chromium(III) chromate is reasonable, however the structure indicates a near close packed O lattice with CrVI in tetrahedral positions and CrIII in octahedral.Axiosaurus (talk) 09:01, 25 May 2014 (UTC)
 * Sceptical about chromous chromate, Cr2O4 - there is definitely an oxide CrO2 - which is not mixed valent containing CrIV - it's magnetic and once used on "Cr" tape cassettes. Axiosaurus (talk) 10:49, 25 May 2014 (UTC)


 * A search of Chemical Abstracts reveals that this material is extremely obscure. The title is catchy but misleading as the material apparently does not retain the chromate subunits with terminal oxide ligands. My recommendation is to convert this thing into a redirect to an article on more conventional chromium oxide. --Smokefoot (talk) 00:17, 28 May 2014 (UTC)


 * I say leave it in; it's food for thought. Don't send it to Deletionpedia. [Fairness: I added this page in 2013. But the smart German page already existed since 2008.] The taught standard naming of inorganic chemistry (one-from-column-A (cation), one-from-column-B (anion)) suggests the possibility of chromium(III) chromate, but is it real? Does it ionize in solution, as implied and shown? If yes, do the chromium atoms stay put in chromium(III) and chromate ions, or do they trade off (resonance structures)? Even if it ionizes some other way, does it react stoichiometrically as if it were chromium(III) + chromate? If it doesn't ionize at all, then why is it soluble? If it's merely a mixed-valence oxide, then why its chemical formula constant (all integers)? If chromium(III) chromate is a fantasy, then that fact makes Cr2(CrO4)3 EVEN MORE interesting [mention it in the article!], because this stuff has been catalogued, sold and purchased, shipped and received with CAS numbers, so someone thinks it is real, even if it is really something else. It can't go away any more than caloric theory or luminiferous aether. Chromium oxide is already a disambiguation page, linking to the (II), (III), (IV), and (VI) oxides (not all soluble; not all clearly available as monomers), plus unstable Chromium(VI) oxide peroxide, and mention but no link for "Mixed valence species, such as Cr8O21" - which are not addressed on those oxides pages nor on the Chromium page. Even if "chromium mixed-valence oxides" had a page, and chromium(III) chromate turns out to be one of them, chromium(III) chromate remains notable as a theoretical compound, a suspected compound that turned out to be one of those mixed-valence oxides. The German page says it often occurs as hexahydrate: "Es tritt häufig auch als Hexahydrat Cr2(CrO4)3·6H2O auf." -A876 (talk) 06:57, 4 June 2014 (UTC)