| Popis: |
The crystal structure of KClO4 has been completely redetermined. The atomic parameters are found to be different from those reported previously for this crystal. The crystals are orthorhombic with space groupPnma and 4 molecules in a cell of edgesa = 8·83 A,b = 5·65 A andc = 7·24 A. The analyses of the structure and the refinement of parameters were carried out by the iteration process of difference synthesis technique. The very prominent diffraction effects encountered in the present case has been pointed out. A procedure involving removal of heavy atom contributions from the structure factors and the computation of Fourier map utilising these coefficients, was adopted to confirm the existence of these diffraction effects. The final discrepancy index calculated for the (hol) and (hko) zones were found to be 0·156 and 0·145 respectively. This value estimated after the removal of the heavy atoms K and Cl from the structure, amounted to 0·235. In the structure each chlorine atom is surrounded by 4 oxygens at a mean distance of 1·46 A which lie at the corners of a nearly regular tetrahedron with Cl at the centre. Each K ion is surrounded by 12 oxygen atoms at an average distance of 3·1 A. Tables are given for the various atomic co-ordinates and inter-atomic distances. Similarity of this structure to its two isomorphs has been pointed out. |
