Synthesis Methods for Ce(CrO4)2 · xH2O and Crystal Structures of K2CrSO7, (NH4)2Cr2O7 and Na2Cr2O7 · 2H2O

Journal article, 2007

New and quick methods to synthesize Ce(CrO4)2 · 2H2O and Ce(CrO4)2 · H2O, giving high yields, are described. The methods are based on exchange reactions by refluxing in water or on solid state reactions. The first crystal structure containing a chromatosulfato ion is presented. K2CrSO7 belongs to space group P21/n with a=7.4024(1), b=7.3908(1), c=12.9883(2) Å , β=90.021(1)◦ and Z = 4. The CrSO72− ion, consisting of one chromate group sharing one oxygen atom with one sulfate group, has a pseudo syn-C2v conformation with eclipsed oxygen atoms. K2CrSO7 forms a three dimensional network of CrSO72− ions held together by the charge balancing potassium ions, with the general structural features common with dichromate-like structures. The redetermination of the structures of (NH4)2Cr2O7 (space group C2/c, with hydrogen atoms located) and Na2Cr2O7 · 2H2O (space group P21, with hydrogen atoms located and the absolute structure established) are reported.