Acta Crystallographica Section B

Structural Science

Volume 57, Part 3 (June 2001)

research papers

Acta Cryst. (2001). B57, 386-393 [ doi:10.1107/S0108768101002166 ]

Average structure of the composite crystal urea/octanedioic acid at room temperature within the superspace formalism

I. Peral, G. Madariaga, V. Petrícek and T. Breczewski

Abstract: The average structure of the composite urea/octanedioic acid has been refined using the superspace formalism [superspace group H'3₁21(00 [gamma] )00 $\bar{1}$ ]. Modulation effects seem to be almost negligible. The guest substructure appears to be largely disordered and has been modelled using rigid units occupying 12 equiprobable different orientations inside the urea tunnels. Guest molecules are slightly tilted with respect to the tunnel axis favouring a stronger guest-guest intratunnel interaction.

Keywords: average; composite; superspace formalism.