ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The preparation and probable structure of managanese (III)-manganate (IV) Mn7O13, 5H2O (a0 = 2,84, c0 = 7,27 Å) and manganous (II)-manganate (IV) Mn7O12, 6H2O are described. Both consist of platelets. Digesting in diluted HNO3 leads to γ-MnO2 (nsutite). Manganese (III)-manganate (IV) is much less stable than the sodiummanganese (II, III)-manganate-(IV) described earlier and looses water easily when heated or in vacuo. Water loss results in breaking down of the double layer lattice, and the product is only two-dimensionally ordered, producing only prism reflections on the X ray diagramm. Heating results in a continuous transition to the two-dimensionally ordered phase, then to a finely divided and very disordered γ-MnO2, and eventually to a finely divided and disordered β-MnO2 (pyrolusite). The transition is topotactical so far, but further heating produces δ-Mn2O3 without obvious topotactical relations to the earlier products. The so-called ‘δ-MnO2’ (birnessite) appears to be a family of finely divided and very disordered varieties of such manganates (IV) with part of the Mn3+ substituted by Mn4+. Since such products usually contain remarkable amounts of alkali ions, they are rather varieties of the earlier described sodiummanganese (II, III)-manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganates (IV) is given. With respect to these results the so-called ‘δ-MnO2’ can no longer be attributed to the true manganese dioxides.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19700530302
