FIRST APPLICATION OF 'INTENSITY SEPARATING DEVICE BASED ON TEXTURE' TO DETERMINATION OF UNKNOWN STRUCTURES.

CRYSTAL STRUCTURE OF ORGANOMETALLIC COMPLEX COMPOUND

Wieslaw Lasocha¹, Ewa Opozda² and Henk Schenk³

¹ Faculty of Chemistry Jagiellonian University, 30-060 Krakow, Poland, lasocha@trurl.ch.uj.edu.pl
² Institute of Chemistry, Pedagogical University, Kielce, Checinska 1, Poland
³ Laboratory for Crystallography, University of Amsterdam, Nieuve Achtergracht 166, 1018 WV Amsterdam, The Netherlands.

Crystal structure of a complex compound of macrocyclic Schiff base with Ni(II) containing 28 atoms in asymmetric unit was solved and refined using laboratory powder data, by combination of a few methods. Since, on the base of single intensities only, we were not able to built a convincing structure model [SHELXS86, SIMPEL88], the set of single intensities was increased by our recently described texture method [1] in which intensities of some overlapping reflections are estimated using texture as intensity separating device. For this purpose few diffraction patterns with different texture were collected on powder diffractometer and Guinier camera. Next, the set of the most appropriate intensities (including overlapping ones) which correspond to all patterns with different texture was determined.

The crystal structure was solved using search for a known fragment on the Patterson map (program PATSEE). Then the structure was refined and the missing atoms were found by XRS82 program. To improve precision of the atomic positions, the structure was refined by GSAS program against a few diffraction patterns with different texture.

To conclude: the complex organometallic structure with 28 atoms in asymmetric unit was solved from laboratory powder data. To improve results of the refinement, a few patterns with different textures were used in the joint refinement. Herewith we present the first application of 'intensity separating device based on texture' in determination of an unknown structure.

Crystal data: a,b,c,b=10.362 A, 18.468 A,12.066 A, 124.53^o space group P 2₁/c (14). Formula C₂₂N₂O₂H₃₂BrNi

This work was supported by Polish Committee for Science Research

[1] W. Lasocha, H. Schenk, J. Appl. Cryst (1997) 30, 561-564