The Crystal Structure of Potassium and Rubidium Oxalate Monoperhydrates, K2C2O4.H2O2 and Rb2C2O4.H2O2.

Neutron profile refinement of potassium and rubidium oxalate monoperhydrates

“…The oxalate ion has the usual distollions (Pedersen, 1967) and is planar. In the K sample the peroxide O-O distance is short at 1.355 (8) ,& which is indicative of some partial random substitution of water for hydrogen peroxide (Pedersen, 1972 (Busing & Levy, 1965) to 180 ° in Na2[C204].…”

“…The geometry of the substructures is given in Tables 3 and 4. It appears that there is an error in Pedersen's (1967) labelling of O(1) and 0(2): the labels have become transposed between the atomic-coordinate list and the table of bond distances and angles• Corrected values are given in Table 3. In those cases where the parameters can be directly compared there is good agreement between these results and those of Pedersen, although the values for the Rb compound are here of higher quality.…”

“…H20 2 (Pedersen & Pedersen, 1964) and indeed there is relatively free rotation about the central O--O bond (Hunt, Leacock, Peters & Hecht, 1965) with ~0 very dependent upon molecular environment. Pedersen's (1967) values of ~0 quoted for the title compounds were obtained by making the unjustified assumption of linear H bonds since the H positions could not be determined. Since the hydrogen bonds have been shown in this study to be relatively linear (Table 5, Fig.…”

“…The alkali-metal oxalate perhydrates are of especial interest since, although not all of these compounds form hydrates, they all form perhydrates. Indeed, they are the only chemical series of perhydrates known: the K and Rb samples are both relatively stable and are isomorphous (Pedersen, 1967 from a solution made up of 87% (w/w) H20 2 diluted c(1) with D20. Exchange is rapid in this system and the 0(3) maximum isotropic substitution possible of D in the D (1) hydrogen peroxide of crystallization was 92%.…”

“…The starting point in both cases was the X-ray structure of Pedersen (1967). The background was estimated by interpolation from regions where Bragg peaks did not occur.…”