Acta Crystallographica Section B

Structural Science

Volume 58, Part 3 Number 2 (June 2002)

research papers

Acta Cryst. (2002). B58, 477-481 [ doi:10.1107/S0108768102001039 ]

Refinement of obverse/reverse twins

R. Herbst-Irmer and G. M. Sheldrick

Abstract: Two examples of structures of obverse/reverse twins are presented. Example (1) is the structure of 2,2,4,4,6,6-hexa-tert-butylcyclotrisiloxane. It crystallizes in R $\overline 3$ c. Example (2) is the structure of [{Li(Me₃Si)₃CAlF₃(thf)}₃LiF(thf)], tris[lithiuim tetrahydrofuran (trimethylsilyl)methyltrifluoroaluminate]lithium fluoride tetrahydrofuran. It crystallizes in R3. Additional to the obverse/reverse twinning this structure shows merohedral twinning. It will be shown how these two structures can be refined with the SHELXL program.

Keywords: obverse/reverse twins; merohedral twinning; SHELXL.