A reinvestigation of the structure of sodium metasilicate, Na2SiO3

The molecular packing of the DADA radicals (Figs. 1 and 2) is very similar in the iodide and the perchlorate. Contrary to the case of the iodide of the DADA radical, we did not find any abnormally short intermolecular distances in the perchlorate, except the distance C(7)-O(1). It is noteworthy that the tetrahedral group CIO~is oriented with the edge 0(2)-0(2 ') approximately parallel to the plane of the DADA radical. The explanation of this remarkable feature is at present not clear.